Toni Fishman wrote:

THIS POST WAS SIMPLE! WE WERE LOOKING FOR TUBES. FINGER POINTING &
HARASSING CONJECTURE WERE NOT NESSARY. IF YOU CANT HELP US WITH TUBES
THEN PLEASE MOVE ON & READ ANOTHER POST. WE'RE SORRY WE EVER POSTED
HERE. IT WAS A BIG MISTAKE. PLEASE EXCUSE OUR COMMENTS, AFTER
READING LORDS POSTS IT WAS CLEAR HE NEED TO KNOW WE'RE NOT GOING TO
LET HIM GET AWAY WITH HIS COMMENTS. IF YOU THINK MY POST WAS BAD READ
SOME OF FLETCHER'S........

Well, I tried to be polite.

OK, asswipe - it's seldom that I run into someone who purports to be
an expert (at something or other) who is as singularly clueless as you
appear to be. It's a sad day indeed when the CEO of an audio gear
manufacturing company is so lacking in basic English language skills
as to imagine he's been insulted by someone who was handing him
an *exceedingly* rare Lord Valve Attaboy.

You stupid ****ing putz. You ignoramus. You dolt. You stinking
mouldering piece of excrement. You tonedeaf sleazebag - may
you spend the rest of your days recording street rappers with
a Mister Microphone plugged into a K-mart ghetto blaster.

Do yourself (and your company) a big favor, you ignorant ****,
and have someone (your secretary, perhaps?) read this entire
thread so he/she can explain to you exactly how full of **** you are.

Hiya, Fletcher. Long time no see. ;-)

Lord Valve
Expert

HEY L.V.! Its been a minute. Guess i haven't missed much huh?!? I
gotta say,"recording rappers with a mister microphone" was the
ultimate! I need a few bucks. Maybe i could "beatbox" for this guy and
he can bless me with a Plexi in return. LOL

Do me a favor if you have a minute and bless me with your expertise on
the "Bogen challenger woes" thread.

You're the best!
see ya round.

HEY L.V.! Its been a minute. Guess i haven't missed much huh?!? I
gotta say,"recording rappers with a mister microphone" was the
ultimate! I need a few bucks. Maybe i could "beatbox" for this guy and
he can bless me with a Plexi in return. LOL

Do me a favor if you have a minute and bless me with your expertise on
the "Bogen challenger woes" thread.

You're the best!
see ya round.

I'm not LV but I don't believe his specific expertise is required to get you
on the correct track regarding your Bogen Challenger.

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

Good luck.

Oh... and Lord, please forgive me for buttin in on your traffic.

--
Steve


"Bro. Yahya" wrote in message
m...
HEY L.V.! Its been a minute. Guess i haven't missed much huh?!? I
gotta say,"recording rappers with a mister microphone" was the
ultimate! I need a few bucks. Maybe i could "beatbox" for this guy and
he can bless me with a Plexi in return. LOL

Do me a favor if you have a minute and bless me with your expertise on
the "Bogen challenger woes" thread.

You're the best!
see ya round.

I'm not LV but I don't believe his specific expertise is required to get you
on the correct track regarding your Bogen Challenger.

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

Good luck.

Oh... and Lord, please forgive me for buttin in on your traffic.

--
Steve


"Bro. Yahya" wrote in message
m...
HEY L.V.! Its been a minute. Guess i haven't missed much huh?!? I
gotta say,"recording rappers with a mister microphone" was the
ultimate! I need a few bucks. Maybe i could "beatbox" for this guy and
he can bless me with a Plexi in return. LOL

Do me a favor if you have a minute and bless me with your expertise on
the "Bogen challenger woes" thread.

You're the best!
see ya round.

Steve O'Neill wrote:

I'm not LV but I don't believe his specific expertise is required to get you
on the correct track regarding your Bogen Challenger.

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

Good luck.

Oh... and Lord, please forgive me for buttin in on your traffic.

Hey, I don't own the joint - I only act like I do. ;-)

Besides, you gave him perfectly good advice.

LV

Steve O'Neill wrote:

I'm not LV but I don't believe his specific expertise is required to get you
on the correct track regarding your Bogen Challenger.

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

Good luck.

Oh... and Lord, please forgive me for buttin in on your traffic.

Hey, I don't own the joint - I only act like I do. ;-)

Besides, you gave him perfectly good advice.

LV

Steve O'Neill wrote:

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

I will second this, and I will also say that that metal can cap on the
Challenger is very, very badly chosen. It's just on the ragged edge of
the voltage rating when the amp is operating, and it's well over the rating
when it powers up. It must be replaced.

It's also possible that the output tubes are shorted too. I'd suggest that
you try firing the thing up with the output tubes removed, but this will
definitely run the supply caps way over their rated voltage.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

I strongly recommend modifying the power supply. The amps were designed
to be as cheap as possible for the lowest grade voice applications. The
power supply is undersized and the caps are on the verge of failing. If
you put modern solid state rectification in there and modern caps, you
will get both a much stiffer supply and a much higher voltage supply. And
yes, you will have to rebias the output stage!

We used to use those as studio talkback amps when I was first starting out.
We'd also change the output tubes for something a little higher current too.
Problem is that there is not much room in there... a 7027 (which was the
cheap super-6L6 replacement at the time) is way too tall and I think the
modern Sovtek 6881WXGT tubes are just as bad.

Oh... and Lord, please forgive me for buttin in on your traffic.

What was the original post about and how did it come to be crossposted
into r.a.p. anway?
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Steve O'Neill wrote:

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

I will second this, and I will also say that that metal can cap on the
Challenger is very, very badly chosen. It's just on the ragged edge of
the voltage rating when the amp is operating, and it's well over the rating
when it powers up. It must be replaced.

It's also possible that the output tubes are shorted too. I'd suggest that
you try firing the thing up with the output tubes removed, but this will
definitely run the supply caps way over their rated voltage.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

I strongly recommend modifying the power supply. The amps were designed
to be as cheap as possible for the lowest grade voice applications. The
power supply is undersized and the caps are on the verge of failing. If
you put modern solid state rectification in there and modern caps, you
will get both a much stiffer supply and a much higher voltage supply. And
yes, you will have to rebias the output stage!

We used to use those as studio talkback amps when I was first starting out.
We'd also change the output tubes for something a little higher current too.
Problem is that there is not much room in there... a 7027 (which was the
cheap super-6L6 replacement at the time) is way too tall and I think the
modern Sovtek 6881WXGT tubes are just as bad.

Oh... and Lord, please forgive me for buttin in on your traffic.

What was the original post about and how did it come to be crossposted
into r.a.p. anway?
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

(Scott Dorsey) wrote in message ...
Steve O'Neill wrote:

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

I will second this, and I will also say that that metal can cap on the
Challenger is very, very badly chosen. It's just on the ragged edge of
the voltage rating when the amp is operating, and it's well over the rating
when it powers up. It must be replaced.

It's also possible that the output tubes are shorted too. I'd suggest that
you try firing the thing up with the output tubes removed, but this will
definitely run the supply caps way over their rated voltage.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

I strongly recommend modifying the power supply. The amps were designed
to be as cheap as possible for the lowest grade voice applications. The
power supply is undersized and the caps are on the verge of failing. If
you put modern solid state rectification in there and modern caps, you
will get both a much stiffer supply and a much higher voltage supply. And
yes, you will have to rebias the output stage!
well i figured i'd have to do a cap job on it anyways but i didnt plan
on changing over to solid state rectification. i only bought it becaus
eit was cheap! i didnt want to throw a whole lotta work into it. it
powers up fine without the rectifier tubes in. blows the fuse as soon
as they're back in. turn it on, rectifiers glow red hot, then poof,
the fuse blows.

We used to use those as studio talkback amps when I was first starting out.
We'd also change the output tubes for something a little higher current too.
Problem is that there is not much room in there... a 7027 (which was the
cheap super-6L6 replacement at the time) is way too tall and I think the
modern Sovtek 6881WXGT tubes are just as bad.

Oh... and Lord, please forgive me for buttin in on your traffic.

What was the original post about and how did it come to be crossposted
into r.a.p. anway?
--scott

(Scott Dorsey) wrote in message ...
Steve O'Neill wrote:

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

I will second this, and I will also say that that metal can cap on the
Challenger is very, very badly chosen. It's just on the ragged edge of
the voltage rating when the amp is operating, and it's well over the rating
when it powers up. It must be replaced.

It's also possible that the output tubes are shorted too. I'd suggest that
you try firing the thing up with the output tubes removed, but this will
definitely run the supply caps way over their rated voltage.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

I strongly recommend modifying the power supply. The amps were designed
to be as cheap as possible for the lowest grade voice applications. The
power supply is undersized and the caps are on the verge of failing. If
you put modern solid state rectification in there and modern caps, you
will get both a much stiffer supply and a much higher voltage supply. And
yes, you will have to rebias the output stage!
well i figured i'd have to do a cap job on it anyways but i didnt plan
on changing over to solid state rectification. i only bought it becaus
eit was cheap! i didnt want to throw a whole lotta work into it. it
powers up fine without the rectifier tubes in. blows the fuse as soon
as they're back in. turn it on, rectifiers glow red hot, then poof,
the fuse blows.

We used to use those as studio talkback amps when I was first starting out.
We'd also change the output tubes for something a little higher current too.
Problem is that there is not much room in there... a 7027 (which was the
cheap super-6L6 replacement at the time) is way too tall and I think the
modern Sovtek 6881WXGT tubes are just as bad.

Oh... and Lord, please forgive me for buttin in on your traffic.

What was the original post about and how did it come to be crossposted
into r.a.p. anway?
--scott

(Bro. Yahya) wrote in message . com...
(Scott Dorsey) wrote in message ...
Steve O'Neill wrote:

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

I will second this, and I will also say that that metal can cap on the
Challenger is very, very badly chosen. It's just on the ragged edge of
the voltage rating when the amp is operating, and it's well over the rating
when it powers up. It must be replaced.

It's also possible that the output tubes are shorted too. I'd suggest that
you try firing the thing up with the output tubes removed, but this will
definitely run the supply caps way over their rated voltage.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

I strongly recommend modifying the power supply. The amps were designed
to be as cheap as possible for the lowest grade voice applications. The
power supply is undersized and the caps are on the verge of failing. If
you put modern solid state rectification in there and modern caps, you
will get both a much stiffer supply and a much higher voltage supply. And
yes, you will have to rebias the output stage!
well i figured i'd have to do a cap job on it anyways but i didnt plan
on changing over to solid state rectification. i only bought it becaus
eit was cheap! i didnt want to throw a whole lotta work into it. it
powers up fine without the rectifier tubes in. blows the fuse as soon
as they're back in. turn it on, rectifiers glow red hot, then poof,
the fuse blows.

We used to use those as studio talkback amps when I was first starting out.
We'd also change the output tubes for something a little higher current too.
Problem is that there is not much room in there... a 7027 (which was the
cheap super-6L6 replacement at the time) is way too tall and I think the
modern Sovtek 6881WXGT tubes are just as bad.

Oh... and Lord, please forgive me for buttin in on your traffic.

What was the original post about and how did it come to be crossposted
into r.a.p. anway?
--scott

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp. i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.
i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.
the 6l6gc's have a bluish haze emmanating from them. i know a blue
glow is normal. i have the amp wired to a 2 x 12 closed-back speaker
cab. the speakers are rated 500 watts and 4 ohm. i wored them in
series for 8 ohms.
well...it sounds like an amp. i realize that this is a 50 year old
amp in need of a complete cap job and its a P.A. amp so i didnt expect
too much. i'm proud i was able to do it myself...with all of the
wonderful help and suggestions from my friends here in the forum. i
thought my wife would give me an attaboy but in retrospect she's
probably ****ed she has to hear that damn guitar again!
i would appreciate any suggestions on improving this amp and some
changes to the tone circuit to improve the "guitar" tone. please post
in layman's terms so i wont go "HUH"!! thanks

(Bro. Yahya) wrote in message . com...
(Scott Dorsey) wrote in message ...
Steve O'Neill wrote:

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

I will second this, and I will also say that that metal can cap on the
Challenger is very, very badly chosen. It's just on the ragged edge of
the voltage rating when the amp is operating, and it's well over the rating
when it powers up. It must be replaced.

It's also possible that the output tubes are shorted too. I'd suggest that
you try firing the thing up with the output tubes removed, but this will
definitely run the supply caps way over their rated voltage.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge of
filter cap continuous voltage ratings and maybe even output tube ratings

I strongly recommend modifying the power supply. The amps were designed
to be as cheap as possible for the lowest grade voice applications. The
power supply is undersized and the caps are on the verge of failing. If
you put modern solid state rectification in there and modern caps, you
will get both a much stiffer supply and a much higher voltage supply. And
yes, you will have to rebias the output stage!
well i figured i'd have to do a cap job on it anyways but i didnt plan
on changing over to solid state rectification. i only bought it becaus
eit was cheap! i didnt want to throw a whole lotta work into it. it
powers up fine without the rectifier tubes in. blows the fuse as soon
as they're back in. turn it on, rectifiers glow red hot, then poof,
the fuse blows.

We used to use those as studio talkback amps when I was first starting out.
We'd also change the output tubes for something a little higher current too.
Problem is that there is not much room in there... a 7027 (which was the
cheap super-6L6 replacement at the time) is way too tall and I think the
modern Sovtek 6881WXGT tubes are just as bad.

Oh... and Lord, please forgive me for buttin in on your traffic.

What was the original post about and how did it come to be crossposted
into r.a.p. anway?
--scott

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp. i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.
i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.
the 6l6gc's have a bluish haze emmanating from them. i know a blue
glow is normal. i have the amp wired to a 2 x 12 closed-back speaker
cab. the speakers are rated 500 watts and 4 ohm. i wored them in
series for 8 ohms.
well...it sounds like an amp. i realize that this is a 50 year old
amp in need of a complete cap job and its a P.A. amp so i didnt expect
too much. i'm proud i was able to do it myself...with all of the
wonderful help and suggestions from my friends here in the forum. i
thought my wife would give me an attaboy but in retrospect she's
probably ****ed she has to hear that damn guitar again!
i would appreciate any suggestions on improving this amp and some
changes to the tone circuit to improve the "guitar" tone. please post
in layman's terms so i wont go "HUH"!! thanks

in article , Bro. Yahya at
wrote on 11/17/04 10:53 PM:

(Bro. Yahya) wrote in message
. com...
(Scott Dorsey) wrote in message
...
Steve O'Neill wrote:

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

I will second this, and I will also say that that metal can cap on the
Challenger is very, very badly chosen. It's just on the ragged edge of
the voltage rating when the amp is operating, and it's well over the rating
when it powers up. It must be replaced.

It's also possible that the output tubes are shorted too. I'd suggest that
you try firing the thing up with the output tubes removed, but this will
definitely run the supply caps way over their rated voltage.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge
of
filter cap continuous voltage ratings and maybe even output tube ratings

I strongly recommend modifying the power supply. The amps were designed
to be as cheap as possible for the lowest grade voice applications. The
power supply is undersized and the caps are on the verge of failing. If
you put modern solid state rectification in there and modern caps, you
will get both a much stiffer supply and a much higher voltage supply. And
yes, you will have to rebias the output stage!
well i figured i'd have to do a cap job on it anyways but i didnt plan
on changing over to solid state rectification. i only bought it becaus
eit was cheap! i didnt want to throw a whole lotta work into it. it
powers up fine without the rectifier tubes in. blows the fuse as soon
as they're back in. turn it on, rectifiers glow red hot, then poof,
the fuse blows.

We used to use those as studio talkback amps when I was first starting out.
We'd also change the output tubes for something a little higher current too.
Problem is that there is not much room in there... a 7027 (which was the
cheap super-6L6 replacement at the time) is way too tall and I think the
modern Sovtek 6881WXGT tubes are just as bad.

Oh... and Lord, please forgive me for buttin in on your traffic.

What was the original post about and how did it come to be crossposted
into r.a.p. anway?
--scott

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp. i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.
i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.
the 6l6gc's have a bluish haze emmanating from them. i know a blue
glow is normal. i have the amp wired to a 2 x 12 closed-back speaker
cab. the speakers are rated 500 watts and 4 ohm. i wored them in
series for 8 ohms.
well...it sounds like an amp. i realize that this is a 50 year old
amp in need of a complete cap job and its a P.A. amp so i didnt expect
too much. i'm proud i was able to do it myself...with all of the
wonderful help and suggestions from my friends here in the forum. i
thought my wife would give me an attaboy but in retrospect she's
probably ****ed she has to hear that damn guitar again!
i would appreciate any suggestions on improving this amp and some
changes to the tone circuit to improve the "guitar" tone. please post
in layman's terms so i wont go "HUH"!! thanks


It's not necessary to post your answer 4 times. I think we got it the first
time.

in article , Bro. Yahya at
wrote on 11/17/04 10:53 PM:

(Bro. Yahya) wrote in message
. com...
(Scott Dorsey) wrote in message
...
Steve O'Neill wrote:

Bob Hedberg's response way above is pretty much on the mark AFAICT; Filter
caps downstream of the rectifier tubes are probably shorted and need
replacing. You pretty much verify this with your subsequent post stating
that no fuses blow when the rectifiers are out of their sockets.

I will second this, and I will also say that that metal can cap on the
Challenger is very, very badly chosen. It's just on the ragged edge of
the voltage rating when the amp is operating, and it's well over the rating
when it powers up. It must be replaced.

It's also possible that the output tubes are shorted too. I'd suggest that
you try firing the thing up with the output tubes removed, but this will
definitely run the supply caps way over their rated voltage.

When you get past this issue you might also consider running the specified
5Y3 rectifiers instead of the 5V4s unless you also modify the PS and/or
output stage bias. Why??? The indirectly heated 5V4 has roughly 1/2 the
voltage drop at load as does the directly heated 5Y3. This MAY result in
continuous DC voltages ~25 or more volts above design. Combine this with
the fact that mains voltages are 120VAC in most parts of the US when the
amp was probably designed for 117 and you're probably on or over the edge
of
filter cap continuous voltage ratings and maybe even output tube ratings

I strongly recommend modifying the power supply. The amps were designed
to be as cheap as possible for the lowest grade voice applications. The
power supply is undersized and the caps are on the verge of failing. If
you put modern solid state rectification in there and modern caps, you
will get both a much stiffer supply and a much higher voltage supply. And
yes, you will have to rebias the output stage!
well i figured i'd have to do a cap job on it anyways but i didnt plan
on changing over to solid state rectification. i only bought it becaus
eit was cheap! i didnt want to throw a whole lotta work into it. it
powers up fine without the rectifier tubes in. blows the fuse as soon
as they're back in. turn it on, rectifiers glow red hot, then poof,
the fuse blows.

We used to use those as studio talkback amps when I was first starting out.
We'd also change the output tubes for something a little higher current too.
Problem is that there is not much room in there... a 7027 (which was the
cheap super-6L6 replacement at the time) is way too tall and I think the
modern Sovtek 6881WXGT tubes are just as bad.

Oh... and Lord, please forgive me for buttin in on your traffic.

What was the original post about and how did it come to be crossposted
into r.a.p. anway?
--scott

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp. i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.
i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.
the 6l6gc's have a bluish haze emmanating from them. i know a blue
glow is normal. i have the amp wired to a 2 x 12 closed-back speaker
cab. the speakers are rated 500 watts and 4 ohm. i wored them in
series for 8 ohms.
well...it sounds like an amp. i realize that this is a 50 year old
amp in need of a complete cap job and its a P.A. amp so i didnt expect
too much. i'm proud i was able to do it myself...with all of the
wonderful help and suggestions from my friends here in the forum. i
thought my wife would give me an attaboy but in retrospect she's
probably ****ed she has to hear that damn guitar again!
i would appreciate any suggestions on improving this amp and some
changes to the tone circuit to improve the "guitar" tone. please post
in layman's terms so i wont go "HUH"!! thanks


It's not necessary to post your answer 4 times. I think we got it the first
time.

"Bro. Yahya" wrote in message
om...

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp.

Buy or borrow a voltmeter and measure the voltage across that cap. If it's
more than 450, that cap isn't long for this world.

i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.

Shouldn't hurt.

i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.

No; if you do that they'll blow up. You want to wire caps in series, with a
voltage divider to put half of the voltage on the junction. Like this:

----|---------|----
| |
cap resistor
| |
|---------|
| |
cap resistor
| |
-------------------

Putting caps in series like this doubles the effective voltage rating (so
250V caps will work up to 500V) but halves the capacitance (so two 8uF caps
will become a 4uF composite cap, which will make the hum worse because it's
too small). A couple of 100uF 450V caps in series ought to be nice and
bomb-proof. Make the resistors 270k 2W and you should be okay. You can get
the caps and resistors from www.digikey.com .

Peace,
Paul

"Bro. Yahya" wrote in message
om...

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp.

Buy or borrow a voltmeter and measure the voltage across that cap. If it's
more than 450, that cap isn't long for this world.

i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.

Shouldn't hurt.

i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.

No; if you do that they'll blow up. You want to wire caps in series, with a
voltage divider to put half of the voltage on the junction. Like this:

----|---------|----
| |
cap resistor
| |
|---------|
| |
cap resistor
| |
-------------------

Putting caps in series like this doubles the effective voltage rating (so
250V caps will work up to 500V) but halves the capacitance (so two 8uF caps
will become a 4uF composite cap, which will make the hum worse because it's
too small). A couple of 100uF 450V caps in series ought to be nice and
bomb-proof. Make the resistors 270k 2W and you should be okay. You can get
the caps and resistors from www.digikey.com .

Peace,
Paul

Paul Stamler wrote:
"Bro. Yahya" wrote in message
. com...

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp.

Buy or borrow a voltmeter and measure the voltage across that cap. If it's
more than 450, that cap isn't long for this world.

Digi-Key carries Panasonic caps up to 600V, although your capacitance
values are limited. Replacing that 16 uF with a slightly higher value
might not be a bad either.

i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.

No; if you do that they'll blow up. You want to wire caps in series, with a
voltage divider to put half of the voltage on the junction. Like this:

High voltage caps are not TOO hard to get. If you absolutely HAVE to use metal
can types, call Antique Electronics Supply in Arizona. Replace the paper
caps in there with modern film capacitors if you want cleaner sound.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Paul Stamler wrote:
"Bro. Yahya" wrote in message
. com...

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp.

Buy or borrow a voltmeter and measure the voltage across that cap. If it's
more than 450, that cap isn't long for this world.

Digi-Key carries Panasonic caps up to 600V, although your capacitance
values are limited. Replacing that 16 uF with a slightly higher value
might not be a bad either.

i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.

No; if you do that they'll blow up. You want to wire caps in series, with a
voltage divider to put half of the voltage on the junction. Like this:

High voltage caps are not TOO hard to get. If you absolutely HAVE to use metal
can types, call Antique Electronics Supply in Arizona. Replace the paper
caps in there with modern film capacitors if you want cleaner sound.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Paul Stamler" wrote in message ...
"Bro. Yahya" wrote in message
om...

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp.

Buy or borrow a voltmeter and measure the voltage across that cap. If it's
more than 450, that cap isn't long for this world.

i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.

Shouldn't hurt.

i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.

No; if you do that they'll blow up. You want to wire caps in series, with a
voltage divider to put half of the voltage on the junction. Like this:

----|---------|----
| |
cap resistor
| |
|---------|
| |
cap resistor
| |
-------------------

Putting caps in series like this doubles the effective voltage rating (so
250V caps will work up to 500V) but halves the capacitance (so two 8uF caps
will become a 4uF composite cap, which will make the hum worse because it's
too small). A couple of 100uF 450V caps in series ought to be nice and
bomb-proof. Make the resistors 270k 2W and you should be okay. You can get
the caps and resistors from www.digikey.com .

Peace,
Paul

thanks paul
there is a rectangular object 5000-7 R717A [resistor ?] attached to
the cap. it started smoking today and now i get loud hum and
motorboating. i dont have a clue.
imeasured the dc across the cap and it was over 500. ill have to
change that. when i turn the amp off the dc drops to zero. i
understand the series / paralel thing now but being unversed in
diagrams i dont understand the wiring or the resistors in your
diagram. could you elaborate?'thanks for your help.

"Paul Stamler" wrote in message ...
"Bro. Yahya" wrote in message
om...

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp.

Buy or borrow a voltmeter and measure the voltage across that cap. If it's
more than 450, that cap isn't long for this world.

i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.

Shouldn't hurt.

i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.

No; if you do that they'll blow up. You want to wire caps in series, with a
voltage divider to put half of the voltage on the junction. Like this:

----|---------|----
| |
cap resistor
| |
|---------|
| |
cap resistor
| |
-------------------

Putting caps in series like this doubles the effective voltage rating (so
250V caps will work up to 500V) but halves the capacitance (so two 8uF caps
will become a 4uF composite cap, which will make the hum worse because it's
too small). A couple of 100uF 450V caps in series ought to be nice and
bomb-proof. Make the resistors 270k 2W and you should be okay. You can get
the caps and resistors from www.digikey.com .

Peace,
Paul

thanks paul
there is a rectangular object 5000-7 R717A [resistor ?] attached to
the cap. it started smoking today and now i get loud hum and
motorboating. i dont have a clue.
imeasured the dc across the cap and it was over 500. ill have to
change that. when i turn the amp off the dc drops to zero. i
understand the series / paralel thing now but being unversed in
diagrams i dont understand the wiring or the resistors in your
diagram. could you elaborate?'thanks for your help.

Bro. Yahya wrote:

thanks paul
there is a rectangular object 5000-7 R717A [resistor ?] attached to
the cap. it started smoking today and now i get loud hum and
motorboating. i dont have a clue.

That is a power resistor. It is smoking because something downstream from
it is drawing way too much current. Probably this is because of a cap that
is a short, or a tube stage that is misbiased due to a bad coupling cap.
ALL of the electrolytics will be bad. Some of the paper caps will probably
be bad too.

imeasured the dc across the cap and it was over 500. ill have to
change that. when i turn the amp off the dc drops to zero. i
understand the series / paralel thing now but being unversed in
diagrams i dont understand the wiring or the resistors in your
diagram. could you elaborate?'thanks for your help.

The capacitors are in series with one another, with a resistor in parallel
with each one so they share load. But frankly, just buy a 600V capacitor.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Bro. Yahya wrote:

thanks paul
there is a rectangular object 5000-7 R717A [resistor ?] attached to
the cap. it started smoking today and now i get loud hum and
motorboating. i dont have a clue.

That is a power resistor. It is smoking because something downstream from
it is drawing way too much current. Probably this is because of a cap that
is a short, or a tube stage that is misbiased due to a bad coupling cap.
ALL of the electrolytics will be bad. Some of the paper caps will probably
be bad too.

imeasured the dc across the cap and it was over 500. ill have to
change that. when i turn the amp off the dc drops to zero. i
understand the series / paralel thing now but being unversed in
diagrams i dont understand the wiring or the resistors in your
diagram. could you elaborate?'thanks for your help.

The capacitors are in series with one another, with a resistor in parallel
with each one so they share load. But frankly, just buy a 600V capacitor.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Paul Stamler" wrote in message ...
"Bro. Yahya" wrote in message
om...

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp.

Buy or borrow a voltmeter and measure the voltage across that cap. If it's
more than 450, that cap isn't long for this world.

i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.

Shouldn't hurt.

i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.

No; if you do that they'll blow up. You want to wire caps in series, with a
voltage divider to put half of the voltage on the junction. Like this:

----|---------|----
| |
cap resistor
| |
|---------|
| |
cap resistor
| |
-------------------

Putting caps in series like this doubles the effective voltage rating (so
250V caps will work up to 500V) but halves the capacitance (so two 8uF caps
will become a 4uF composite cap, which will make the hum worse because it's
too small). A couple of 100uF 450V caps in series ought to be nice and
bomb-proof. Make the resistors 270k 2W and you should be okay. You can get
the caps and resistors from www.digikey.com .

Peace,
Paul

i think i found a 20uf 500volt cap. should that be okay? can i go with
a 50uf 500 volt?

"Paul Stamler" wrote in message ...
"Bro. Yahya" wrote in message
om...

i replaced the rect tubes today and changed the filter cap to a 16uf
450 volt.
i could not find a 500 volt one. i hope this wont hurt the amp.

Buy or borrow a voltmeter and measure the voltage across that cap. If it's
more than 450, that cap isn't long for this world.

i also
changed the 6l6gb's with 6l6gc's i hope this wont do any harm either.

Shouldn't hurt.

i also change the 2 12ax7's. the amp fired right up. bit of a hum that
doesnt go away when i turn the pots etc. its pretty contant. tubes
break up around 5. not very loud either. i figure i should wire up 2-
8uf 250 volts caps in parallel and change all the other caps in the
amp.

No; if you do that they'll blow up. You want to wire caps in series, with a
voltage divider to put half of the voltage on the junction. Like this:

----|---------|----
| |
cap resistor
| |
|---------|
| |
cap resistor
| |
-------------------

Putting caps in series like this doubles the effective voltage rating (so
250V caps will work up to 500V) but halves the capacitance (so two 8uF caps
will become a 4uF composite cap, which will make the hum worse because it's
too small). A couple of 100uF 450V caps in series ought to be nice and
bomb-proof. Make the resistors 270k 2W and you should be okay. You can get
the caps and resistors from www.digikey.com .

Peace,
Paul

i think i found a 20uf 500volt cap. should that be okay? can i go with
a 50uf 500 volt?