I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either. Was
playing it the other day and the volume suddenly dropped way off and
the amp went dead. Assuming it was a loose connection somewhere, I
tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

"Scanty" wrote in message
om...
I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either. Was
playing it the other day and the volume suddenly dropped way off and
the amp went dead. Assuming it was a loose connection somewhere, I
tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Does the amp come on at all? Fuse not blown?
You are way overdue replacing those EL84s.
The amp does not have a standby switch and does not
have a rectifier tube which means those power tubes
(the EL84s) are good for about 3-6 months depending
on how often and how loud you play. In the meantime,
you most likely stressed the power transformer letting
them run as hot as you did. Then again, you may have a broken
connection in the circuit somewhere that was once intermittent.
If you don't have a meter, a schematic or any of the other
necessary tech tools and don't know what you are doing,
take it to a tech unless you want to tamper with it and
end up paying for a more expensive repair. Sure, there's
not much to those amps, but one can easily muck it up
further if they don't know what they're doing.

Ed @ Sonic Surgery

(Scanty) wrote in
om:

I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either. Was
playing it the other day and the volume suddenly dropped way off and
the amp went dead. Assuming it was a loose connection somewhere, I
tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?


When I opened my Blues Jr. I was appauled by the shoddy components. I had
to do a LOT of resoldering and jumping. And this was just the result of the
amp shaking for years as a result of playing loud.

Many of the things I found in there were easy to eyeball - especially on
that block that houses the speaker jack and the remote switch. Cheap
plastic crap mounted to a PC board.

I don't know if that's YOUR problem, but, I'd check that stuff out with the
amp unplugged.

"Elvis Kabong" wrote in message
.. .
means those power tubes
(the EL84s) are good for about 3-6 months depending
on how often and how loud you play. In the meantime,
you most likely stressed the power transformer letting
them run as hot as you did. Then
No reasonably well designed amp is going to eat output valves every 3-6
months. If this happens, the tubes are not being run at the correct
operating point

again, you may have a broken
connection in the circuit somewhere that was once intermittent.
This is probably correct. I would check to see if the heaters are getting
any voltage. Then disconnext the power transformer and see if it is
producing heater voltage (DO NOT try this if you don't know what you are
doing. There is several hundred volts under the chassis (even when it is
turned off and unplugged depending on design).

If you don't have a meter, a schematic or any of the other
necessary tech tools and don't know what you are doing,
take it to a tech unless you want to tamper with it and
end up paying for a more expensive repair. Sure, there's
not much to those amps, but one can easily muck it up
further if they don't know what they're doing.


Follow this advise

Scanty wrote:

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot).

What exactly was glowing bright orange? If the heaters inside the tubes
are glowing that's normal (otherwise they wouldn't work). If the plates
are glowing bright orange then either:

1. The tubes are bad
2. They are biased much too hot
3. The coupling caps are bad - not likely if the amp is only 4 years
old.

Best regards,

Mikkel C. Simonsen

Scanty wrote:

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot).

sigh

Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?


Tubes ain't aspirins.

You can't feed a sick amp a couple of 'em and have it feel
better in the morning.

You have cracked joints on the power tube PC board.
Very common in those amps. If you can't solder, you're
headed for the repair shop.

Lord Valve
Expert

As the others have mentioned, if you can follow a schematic and have at
least a digital meter, open it up and look for burn traces or resistors.
The link below has some info on lower the bias, when you get yours running
again.
I have one of these also, and through the winter plan to get the idle bias
down a bit.
Good Luck!!
Dan
http://mywebpages.comcast.net/machrone/bluesjunior.htm

"Scanty" wrote in message
om...
I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either. Was
playing it the other day and the volume suddenly dropped way off and
the amp went dead. Assuming it was a loose connection somewhere, I
tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Scanty apparently posted:

....
I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot).

Nope. The bright orange glow was almost certainly
from the tube filaments, in the middle of the tubes.
That means pwer is getting to the filaments. If you
don't have that, you won't have sound.

If the plates (the big gray or black things closest
to the glass were glowing red, then things are too
hot, and you definitely have a problem.

Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Scorch marks on the valves generally means something
blew up, burned, or at least arc'd nastily a while
on the *outside* of the tubes. You'd have to run them
absurdly hot (plates glowing like stop lights) to have
the tube scorch the glass. (I've seen this happen, and
it ain't pretty.)

Listen to Lord Valve; he gave you the skinny on what
needs to happen next. Where are you located?

-Miles


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On Fri, 15 Oct 2004 09:15:21 -0700, Scanty wrote:

I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either. Was
playing it the other day and the volume suddenly dropped way off and
the amp went dead. Assuming it was a loose connection somewhere, I
tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

If you are unsure about what you are doing then *please* hand the problem
over to someone who does! The voltages in valve amps (even small ones) can
kill you. *Please* at least have someone there with you who knows about
valve stuff while you "play".

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info

"Not A Phil" wrote in message
news
Scanty apparently posted:

...
I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot).

Nope. The bright orange glow was almost certainly
from the tube filaments, in the middle of the tubes.
That means pwer is getting to the filaments. If you
don't have that, you won't have sound.

If the plates (the big gray or black things closest
to the glass were glowing red, then things are too
hot, and you definitely have a problem.

Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Scorch marks on the valves generally means something
blew up, burned, or at least arc'd nastily a while
on the *outside* of the tubes. You'd have to run them
absurdly hot (plates glowing like stop lights) to have
the tube scorch the glass. (I've seen this happen, and
it ain't pretty.)

Listen to Lord Valve;

**** Lard Valve, you toady suck, Miles.




he gave you the skinny on what
needs to happen next. Where are you located?

-Miles


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News==----
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Newsgroups
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Elvis Kabong wrote:
"Scanty" wrote in message
om...
I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either.
Was playing it the other day and the volume suddenly dropped way off
and the amp went dead. Assuming it was a loose connection somewhere,
I tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Does the amp come on at all? Fuse not blown?
You are way overdue replacing those EL84s.
The amp does not have a standby switch and does not
have a rectifier tube which means those power tubes
(the EL84s) are good for about 3-6 months depending
on how often and how loud you play. In the meantime,
you most likely stressed the power transformer letting
them run as hot as you did. Then again, you may have a broken
connection in the circuit somewhere that was once intermittent.
If you don't have a meter, a schematic or any of the other
necessary tech tools and don't know what you are doing,
take it to a tech unless you want to tamper with it and
end up paying for a more expensive repair. Sure, there's
not much to those amps, but one can easily muck it up
further if they don't know what they're doing.

Ed @ Sonic Surgery

Elvis Kabong wrote:
"Scanty" wrote in message
om...
I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either.
Was playing it the other day and the volume suddenly dropped way off
and the amp went dead. Assuming it was a loose connection somewhere,
I tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Does the amp come on at all? Fuse not blown?
You are way overdue replacing those EL84s.
The amp does not have a standby switch and does not
have a rectifier tube which means those power tubes
(the EL84s) are good for about 3-6 months depending
on how often and how loud you play. In the meantime,
you most likely stressed the power transformer letting
them run as hot as you did. Then again, you may have a broken
connection in the circuit somewhere that was once intermittent.
If you don't have a meter, a schematic or any of the other
necessary tech tools and don't know what you are doing,
take it to a tech unless you want to tamper with it and
end up paying for a more expensive repair. Sure, there's
not much to those amps, but one can easily muck it up
further if they don't know what they're doing.

Ed @ Sonic Surgery


Some valves glow very orange depends on the valve been using and building
valve amps 25 years

your EL84's should last longer than the 3-6 months talked of,

When for what ever reason valves die they often take out an internal fuse
and sometimes a resistor if the amps been made on the cheap

Some resistors that should be flash proof and on long legs to protect
everything are not

I see its been pointed out that

"You have cracked joints on the power tube PC board"


My money is on a burnt out resistor causing that.

To give your amp a chance of not blowing again use SOVTEK EL-84M if they do
not last long then use SOVTEK EL-84M ( Military Grade ) - Not designed for
audio applications, will handle higher voltages in a poorly designed amp,
but sound flabby on the low-end, with splattered distortion. Wattage is
increased by use of these tubes, but at the cost of tone.


JUST REMEMBER THE valve uses 6.3 volts on the heater but 550 volts Max anode
they can kill



--
Dave xxxx
www.davewhitter.myby.co.uk

Music is Art - Audio is Engineering
Steam is Fun

"Form@C" wrote in message
news
On Fri, 15 Oct 2004 09:15:21 -0700, Scanty wrote:

I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either. Was
playing it the other day and the volume suddenly dropped way off and
the amp went dead. Assuming it was a loose connection somewhere, I
tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

If you are unsure about what you are doing then *please* hand the problem
over to someone who does! The voltages in valve amps (even small ones) can
kill you. *Please* at least have someone there with you who knows about
valve stuff while you "play".

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info



My apologies if you are already familiar with valve technology and fault
finding.

If you end up measuring voltages on the valve pins, keep one hand in your
pocket - I know through experience!

Also if you use a digital voltmeter, they will tend to read high as they
don't load the circuit under measurement. Circuit diagrams should specify
what type of meter was used - AVO 7 (1K Ohms/Volt) or AVO 8 (20k
Ohms/volt).

If you haven't got a circuit diagram it's worth tracing out the circuit for
future reference. You can then compare it against other circuits to give you
an idea of component values.


--
Regards

Jim Worsley

The corporation muck cart was filled up to the brim
The driver overbalanced and found he couldn't swim.
He sank right to the bottom just like a little stone.
That's when they heard him singing "there's no place like home"

(You never know what you will find on a web search)

Elvis Kabong wrote:
"Not A Phil" wrote in message
news
Scanty apparently posted:

...

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot).

Nope. The bright orange glow was almost certainly
from the tube filaments, in the middle of the tubes.
That means pwer is getting to the filaments. If you
don't have that, you won't have sound.

If the plates (the big gray or black things closest
to the glass were glowing red, then things are too
hot, and you definitely have a problem.


Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Scorch marks on the valves generally means something
blew up, burned, or at least arc'd nastily a while
on the *outside* of the tubes. You'd have to run them
absurdly hot (plates glowing like stop lights) to have
the tube scorch the glass. (I've seen this happen, and
it ain't pretty.)

Listen to Lord Valve;


**** Lard Valve, you toady suck, Miles.


I'm sure the original poster will find _that_comment helpful.
I wonder if by "scorch marks"
he is referring to the brown gunk that appears in
Sovtek EL84s after they've been run awhile? I think that's
pretty much normal.

Dave xxxxx wrote:

Elvis Kabong wrote:
"Scanty" wrote in message
om...
I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either.
Was playing it the other day and the volume suddenly dropped way off
and the amp went dead. Assuming it was a loose connection somewhere,
I tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Does the amp come on at all? Fuse not blown?
You are way overdue replacing those EL84s.
The amp does not have a standby switch and does not
have a rectifier tube which means those power tubes
(the EL84s) are good for about 3-6 months depending
on how often and how loud you play. In the meantime,
you most likely stressed the power transformer letting
them run as hot as you did. Then again, you may have a broken
connection in the circuit somewhere that was once intermittent.
If you don't have a meter, a schematic or any of the other
necessary tech tools and don't know what you are doing,
take it to a tech unless you want to tamper with it and
end up paying for a more expensive repair. Sure, there's
not much to those amps, but one can easily muck it up
further if they don't know what they're doing.

Ed @ Sonic Surgery

Some valves glow very orange depends on the valve been using and building
valve amps 25 years

your EL84's should last longer than the 3-6 months talked of,

When for what ever reason valves die they often take out an internal fuse
and sometimes a resistor if the amps been made on the cheap

Some resistors that should be flash proof and on long legs to protect
everything are not

I see its been pointed out that

"You have cracked joints on the power tube PC board"

My money is on a burnt out resistor causing that.

To give your amp a chance of not blowing again use SOVTEK EL-84M if they do
not last long then use SOVTEK EL-84M ( Military Grade ) - Not designed for
audio applications, will handle higher voltages in a poorly designed amp,
but sound flabby on the low-end, with splattered distortion. Wattage is
increased by use of these tubes, but at the cost of tone.

Stick to audiophool crap - it's glaringly obvious you know
very little about guitar amps.

LV

Dan Nicotera wrote:

As the others have mentioned, if you can follow a schematic and have at
least a digital meter, open it up and look for burn traces or resistors.
The link below has some info on lower the bias, when you get yours running
again.
I have one of these also, and through the winter plan to get the idle bias
down a bit.
Good Luck!!
Dan
http://mywebpages.comcast.net/machrone/bluesjunior.htm

Damn, Fender should have hired this guy for their R&D department!!!

Which, makes you think, who the hell they had there that who made this thing in the first place.

Further testament, Fender forgot how to make a good sounding guitar amp.

Sure is nice of this guy to help Fender out for FREE!!!!!!


Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers

Lord Valve wrote:



Stick to audiophool crap - it's glaringly obvious you know
very little about guitar amps.

LV



Is it **** for brains, item here on fitting valves I spoke of


http://home.alltel.net/vintage/drz.htm

Item by Mike Zaite of DR. Z AMPS. - John Grimm (Vintage Music)

Information on valves blowing resistors then damaging board, by being short
legged, none flam proof, came from Peter Walker years ago?

you know invented Quad II


So I suggest you swap "Lord" for something better? and a better discription
of the real you. :-)

In article iuscd.10069$xb.8172
@text.news.blueyonder.co.uk, davewhit181
@hotmail.com says...
Lord Valve wrote:

Stick to audiophool crap - it's glaringly obvious you know
very little about guitar amps.


Is it **** for brains, item here on fitting valves I spoke of
snippage
So I suggest you swap "Lord" for something better? and a better discription
of the real you. :-)
================================================

Oh, here we go, again!!! LoL

Dave xxxxx wrote:

Lord Valve wrote:


Stick to audiophool crap - it's glaringly obvious you know
very little about guitar amps.

LV

Is it **** for brains, item here on fitting valves I spoke of

http://home.alltel.net/vintage/drz.htm

Item by Mike Zaite of DR. Z AMPS. - John Grimm (Vintage Music)

Information on valves blowing resistors then damaging board, by being short
legged, none flam proof, came from Peter Walker years ago?

you know invented Quad II

So I suggest you swap "Lord" for something better? and a better discription
of the real you. :-)


1) **** Quad II. It ain't a guitar amp.

2) I've fixed *dozens* of Blues Juniors. A Blues Junior is a mass-produced
cheapass low-quality guitar amp, with *wave soldered* PC boards. They
are *famous* for developing bad joints - *especially* on the tube sockets.

3) The OP states his tubes don't light up. There are no resistors in the
filament circuit which can fry and cause this.

4) Buy a clue somewhere.


Lord Valve
Expert

Jim Worsley wrote:

Also if you use a digital voltmeter, they will tend to read high as they
don't load the circuit under measurement. Circuit diagrams should specify
what type of meter was used - AVO 7 (1K Ohms/Volt) or AVO 8 (20k
Ohms/volt).

Nonsense.

They will read *correctly* because they don't load the circuit.
That's the *idea*.

Lord Valve
Expert

These cheap pcb amps are nothing but problems, if you ask me.

I say point to point it.

Get rid of the extra knobs and only keep the volume.

Twang




As the others have mentioned, if you can follow a schematic and have at
least a digital meter, open it up and look for burn traces or resistors.
The link below has some info on lower the bias, when you get yours running
again.
I have one of these also, and through the winter plan to get the idle bias
down a bit.
Good Luck!!
Dan
http://mywebpages.comcast.net/machrone/bluesjunior.htm

"Scanty" wrote in message
om...
I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either. Was
playing it the other day and the volume suddenly dropped way off and
the amp went dead. Assuming it was a loose connection somewhere, I
tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Lord Valve wrote:


Dave xxxxx wrote:


Lord Valve wrote:


Stick to audiophool crap - it's glaringly obvious you know
very little about guitar amps.

LV

Is it **** for brains, item here on fitting valves I spoke of

http://home.alltel.net/vintage/drz.htm

Item by Mike Zaite of DR. Z AMPS. - John Grimm (Vintage Music)

Information on valves blowing resistors then damaging board, by being short
legged, none flam proof, came from Peter Walker years ago?

you know invented Quad II

So I suggest you swap "Lord" for something better? and a better discription
of the real you. :-)



1) **** Quad II. It ain't a guitar amp.

2) I've fixed *dozens* of Blues Juniors. A Blues Junior is a mass-produced
cheapass low-quality guitar amp, with *wave soldered* PC boards. They
are *famous* for developing bad joints - *especially* on the tube sockets.

3) The OP states his tubes don't light up. There are no resistors in the
filament circuit which can fry and cause this.

4) Buy a clue somewhere.

Pearls before swine.

O.P. please listen to LV and if you don't
feel confident with lethal voltages GET A TECH.

best

Andy

Lord Valve wrote in message ...
Jim Worsley wrote:

Also if you use a digital voltmeter, they will tend to read high as they
don't load the circuit under measurement. Circuit diagrams should specify
what type of meter was used - AVO 7 (1K Ohms/Volt) or AVO 8 (20k
Ohms/volt).

Nonsense.

They will read *correctly* because they don't load the circuit.
That's the *idea*.

Lord Valve
Expert

Yes. If you have an old cct diag marked with 1k or 20k meter readings
though, unloaded readings will not always correspond to those marked
on the diag.

I would go with an analogue meter rather than digital too: far more
use on Vs that arent entirely steady. Analogue meters do have serious
advantages.

NT

"Jim Worsley"

Also if you use a digital voltmeter, they will tend to read high as they
don't load the circuit under measurement. Circuit diagrams should specify
what type of meter was used - AVO 7 (1K Ohms/Volt) or AVO 8 (20k
Ohms/volt).



** Any DC meter with a sensitivity of only 1Kohms / Volt would be utterly
useless for measuring voltages in a tube amplifier. The loading of the
circuit by the meter would seriously disturb operation of preamp stages and
render any voltage readings meaningless.

A multimeter of 20 kohms /volt was the norm in the 1960s and early 70s until
FET VOMs and then DMMs (with 10 Mohms/volt) took over the game.


BTW The AVO model 7 dates from WW2 and is a collector's item.



.............. Phil

"N. Thornton"

I would go with an analogue meter rather than digital too: far more
use on Vs that arent entirely steady.


** Huh - so you read wobbly DC voltages a lot then ???

Long as the *average value* of the DC voltage is reasonably steady ( ie
99.9 % of cases) either kind of meter gives correct readings. Digitals are
far more rugged, will autorange, work with either polarity and never get
sticky needles.


Analogue meters do have serious advantages.


** I find the low ohms ranges on a budget 20kohm/volt meter are far better
for *in circuit* testing of semis in amplifiers - but after that it is
mostly all down hill.



............... Phil

N. Thornton wrote:

Lord Valve wrote in message ...
Jim Worsley wrote:

Also if you use a digital voltmeter, they will tend to read high as they
don't load the circuit under measurement. Circuit diagrams should specify
what type of meter was used - AVO 7 (1K Ohms/Volt) or AVO 8 (20k
Ohms/volt).

Nonsense.

They will read *correctly* because they don't load the circuit.
That's the *idea*.

Lord Valve
Expert

Yes. If you have an old cct diag marked with 1k or 20k meter readings
though, unloaded readings will not always correspond to those marked
on the diag.

So - who gives a ****?

It's the *ratio* of the schematic voltages to each other that matters,
not the absolute values.

I would go with an analogue meter rather than digital too: far more
use on Vs that arent entirely steady. Analogue meters do have serious
advantages.

You're a crackpot.

Let me guess - you're logged onto RAT/AGA with a Commodore 64
through a crank telephone, right? Using a 1kbaud modem?

Old **** is good ****, eh? Not when it comes to testgear, not
in my book.

If you want to look at a jittery voltage, a scope is far better for
doing so than an analog meter - the trace will respond way
faster than any mechanical meter movment, and it won't
bang the pin and trash itself if hit with a negative spike.

Lord Valve
Expert

"Phil Allison" wrote in message ...
"N. Thornton"

I would go with an analogue meter rather than digital too: far more
use on Vs that arent entirely steady.


** Huh - so you read wobbly DC voltages a lot then ???

yes, thats why I use them.

NT

"Phil Allison" wrote in message ...
"Jim Worsley"

Also if you use a digital voltmeter, they will tend to read high as they
don't load the circuit under measurement. Circuit diagrams should specify
what type of meter was used - AVO 7 (1K Ohms/Volt) or AVO 8 (20k
Ohms/volt).



** Any DC meter with a sensitivity of only 1Kohms / Volt would be utterly
useless for measuring voltages in a tube amplifier. The loading of the
circuit by the meter would seriously disturb operation of preamp stages and
render any voltage readings meaningless.

wrong again. Crap, certainly, but not useless. A 1k/v meter can
measure a whole number of Vs in a tube amp, though there are plenty it
cant. It can do power rails, low z output Vs, cathode resistors, and
be used to measure currents. Thats why meters were a handy thing to
have in the 1920s.

You can also get arough measure of some Vs indirectly, eg measure
V_cathode and briefly short the grid to ground: the resulting cathode
behaviour will tell you roughly whats going on on the grid. And for
high impedance anode Vs, put it in the anode circuit in current
measure mode, then calculate. Etc.

People have gotten mileage out of far cruder things than 1kpv
voltmeters.


NT

"N. Thornton"
Phil Allison

I would go with an analogue meter rather than digital too: far more
use on Vs that arent entirely steady.


** Huh - so you read wobbly DC voltages a lot then ???

yes, thats why I use them.



** How do you stand all that needle shaking ?????????

Or do YOU shake in phase opposition ???





........... Phil

"N. Thornton"
"Phil Allison"


** Any DC meter with a sensitivity of only 1Kohms / Volt would be utterly
useless for measuring voltages in a tube amplifier. The loading of the
circuit by the meter would seriously disturb operation of preamp stages
and
render any voltage readings meaningless.

wrong again.


** You are clearly not sane.

Crap, certainly, but not useless.


** **** peddlers say that.


A 1k/v meter can
measure a whole number of Vs in a tube amp, though there are plenty it
cant.


** As my post commented - it fails the *useful* test.


You can also get arough measure of some Vs indirectly, eg measure
V_cathode and briefly short the grid to ground: the resulting cathode
behaviour will tell you roughly whats going on on the grid.


** Ever tried the wet finger test ????

For those who like to live on the edge.


And for
high impedance anode Vs, put it in the anode circuit in current
measure mode, then calculate. Etc.


** Even a moving iron amp meter will do that.


People have gotten mileage out of far cruder things than 1kpv
voltmeters.


** Yeah right - some sparkies can judge the AC voltage coming down a
pair of wires the size of the flash from a screwdriver blade shorted across
them for an instant.

With three *tall* sparkies and three *long* handled screwdrivers the phase
sequence on a 33 KV system can be found quite easily as well .........
exciting stuff !!!!





............ Phil

"Phil Allison" wrote in message ...
"Jim Worsley"

Also if you use a digital voltmeter, they will tend to read high as they
don't load the circuit under measurement. Circuit diagrams should specify
what type of meter was used - AVO 7 (1K Ohms/Volt) or AVO 8 (20k
Ohms/volt).
** Any DC meter with a sensitivity of only 1Kohms / Volt would be utterly
useless for measuring voltages in a tube amplifier. The loading of the
circuit by the meter would seriously disturb operation of preamp stages and
render any voltage readings meaningless.
A multimeter of 20 kohms /volt was the norm in the 1960s and early 70s until
FET VOMs and then DMMs (with 10 Mohms/volt) took over the game.

BTW The AVO model 7 dates from WW2 and is a collector's item. Phil

That's right, Jim. BTW, I have an Eiko VTVM (vacuum tube volt meter)
you might like to try (purchase). It's just a shelf ornament to me. It
generates it's own voltage so you don't load down the circuit. It is a
must for amp techs.

Porky

On Fri, 22 Oct 2004 07:54:09 +0000, Lord Valve wrote:
N. Thornton wrote:
[snippage]
Yes. If you have an old cct diag marked with 1k or 20k meter readings
though, unloaded readings will not always correspond to those marked
on the diag.

Tho 1k/V is a pretty cruddy meter. 20k/V should be acceptable.

So - who gives a ****?

It's the *ratio* of the schematic voltages to each other that matters,
not the absolute values.

Yah.

I would go with an analogue meter rather than digital too: far more
use on Vs that arent entirely steady. Analogue meters do have serious
advantages.

You're a crackpot.

Let me guess - you're logged onto RAT/AGA with a Commodore 64
through a crank telephone, right? Using a 1kbaud modem?

Old **** is good ****, eh? Not when it comes to testgear, not
in my book.

I use a lot of computer stuff. I have also learned that the latest
toy/tool is not always the best solution to every problem.

If you want to look at a jittery voltage, a scope is far better for
doing so than an analog meter - the trace will respond way
faster than any mechanical meter movment, and it won't
bang the pin and trash itself if hit with a negative spike.

Well, there are things you can read a bit better on analog meters, like
VU? The mechanical damping and intertia were an integral part of the
behaviour of VU meters used for setting and balancing audio. Right? While
it should be possible to model that with microcomputer signal processing
and display on digital devices, the result seems not to be quite the same.
There is something (nostalgic only?) about the "twitch" of a VU meter. I
will admit that some of the remembered VU behaviour might actually have
been its combination with the characteristics of tubes and magnetics.

I agree that a scope is more accurate and has the advantages that you
mention, but someone experienced with his favorite analog meter can
probably read a couple of parameters simultaneously off an analog meter:
average DC or AC and something about its variability ("twitch"?), while a
digital meter gives you only one value (if you can read the moving #s).
Sometimes a scope trace can also look incomprehensible if you cannot
sync, i.e. if the signal is not truly periodic. As they say, YMMV.

Consider also guitar tuners. I think many still prefer analog mechanical
meters with swinging pointers over them damn blinken lights. I do, even
tho I will also use the blinken lights on my J-Station when I'm too lazy.

--
Juhan Leemet
Logicognosis, Inc.

"N. Thornton" wrote:

"Phil Allison" wrote in message ...
"Jim Worsley"

Also if you use a digital voltmeter, they will tend to read high as they
don't load the circuit under measurement. Circuit diagrams should specify
what type of meter was used - AVO 7 (1K Ohms/Volt) or AVO 8 (20k
Ohms/volt).



** Any DC meter with a sensitivity of only 1Kohms / Volt would be utterly
useless for measuring voltages in a tube amplifier. The loading of the
circuit by the meter would seriously disturb operation of preamp stages and
render any voltage readings meaningless.

wrong again. Crap, certainly, but not useless. A 1k/v meter can
measure a whole number of Vs in a tube amp, though there are plenty it
cant. It can do power rails, low z output Vs, cathode resistors, and
be used to measure currents. Thats why meters were a handy thing to
have in the 1920s.

You can also get arough measure of some Vs indirectly, eg measure
V_cathode and briefly short the grid to ground: the resulting cathode
behaviour will tell you roughly whats going on on the grid. And for
high impedance anode Vs, put it in the anode circuit in current
measure mode, then calculate. Etc.

People have gotten mileage out of far cruder things than 1kpv
voltmeters.

Yeah, like a decent vacuum tube voltmeter,
with input impedance at any F from DC to Mhz
of several megohms at least; just a cathode follower
achieves that.

if you have jittery DC, use an RC LPF.
If you are reading 1 kHz, and you get silly readings marred by
hum and jittery DC, use a HPF with a pole at around
300 Hz.

Such filters can be built into a VTVM, and placed after the
input cathode follower, which is a buffer, and can be made switchable,
so use your brains to make the gear you want.

Always make a measurement with your probes effect in mind.
Never ignore what you are really doing.

I just have a Fluke, good for most things, plus a few
expendable low cost analog meters.
Then I have a 6 range home made signal meter,
2 Hz to 2 MHz, calibrated in dB and volts.
It has a fet follower input, and is all SS discrete. Its about
7 years old now, and I only once blew the fet at the input.
Nice big ex power station analog meter on the front!

I have two CROs. One is a single trace, all SS, except for the TOOBE.
The other is a dual trace, and has slowly lost function after function,
and was worn out from measuring responses and voltages,
but I live in hope, a colleague who is a whiz on this sort of complex
multi chip crap has it nearly all repaired yet again..

Patrick Turner.








NT

Yea

Phil Allison wrote:

"N. Thornton"
Phil Allison

I would go with an analogue meter rather than digital too: far more
use on Vs that arent entirely steady.


** Huh - so you read wobbly DC voltages a lot then ???

yes, thats why I use them.


** How do you stand all that needle shaking ?????????

Or do YOU shake in phase opposition ???

He has a concertina phase inverter, and strange sound comes from his shed
when he measure de voltages...

Patrick Turner.



.......... Phil

"Elvis Kabong" wrote in message ...
"Scanty" wrote in message
om...
I've had a Blues Junior for the last 4 years and never had a problem
with it apart from a loose jack. Never replaced the valves either. Was
playing it the other day and the volume suddenly dropped way off and
the amp went dead. Assuming it was a loose connection somewhere, I
tinkered for a minute, and lo and behold, it worked again. After a
minute, the volume started dropping off until it was dead again.

I had a peek round the back of the amp and noticed that the two EL84s
weren't glowing bright orange like they normally do (I've since
learned that this means that they're biased a bit hot). Assuming the
valves were shot (the glass is covered in scorch marks), I bought two
new ones, but the amp remains dead, and the new valves don't glow
either. Any ideas what it might be? Heater problem?

Does the amp come on at all? Fuse not blown?
You are way overdue replacing those EL84s.
The amp does not have a standby switch and does not
have a rectifier tube which means those power tubes
(the EL84s) are good for about 3-6 months depending
on how often and how loud you play. In the meantime,
you most likely stressed the power transformer letting
them run as hot as you did. Then again, you may have a broken
connection in the circuit somewhere that was once intermittent.
If you don't have a meter, a schematic or any of the other
necessary tech tools and don't know what you are doing,
take it to a tech unless you want to tamper with it and
end up paying for a more expensive repair. Sure, there's
not much to those amps, but one can easily muck it up
further if they don't know what they're doing.

Ed @ Sonic Surgery


3-6 months seems pretty pessimistic???

I play regularily loud and my I've had El34s last for like four years.

Chris

"Phil Allison" wrote in message ...
"N. Thornton"


** Any DC meter with a sensitivity of only 1Kohms / Volt would be utterly
useless for measuring voltages in a tube amplifier. The loading of the
circuit by the meter would seriously disturb operation of preamp stages
and
render any voltage readings meaningless.

wrong again.


** You are clearly not sane.

Crap, certainly, but not useless.


** **** peddlers say that.


A 1k/v meter can
measure a whole number of Vs in a tube amp, though there are plenty it
cant.


** As my post commented - it fails the *useful* test.


You can also get arough measure of some Vs indirectly, eg measure
V_cathode and briefly short the grid to ground: the resulting cathode
behaviour will tell you roughly whats going on on the grid.


** Ever tried the wet finger test ????

For those who like to live on the edge.


And for
high impedance anode Vs, put it in the anode circuit in current
measure mode, then calculate. Etc.


** Even a moving iron amp meter will do that.


People have gotten mileage out of far cruder things than 1kpv
voltmeters.


** Yeah right - some sparkies can judge the AC voltage coming down a
pair of wires the size of the flash from a screwdriver blade shorted across
them for an instant.

With three *tall* sparkies and three *long* handled screwdrivers the phase
sequence on a 33 KV system can be found quite easily as well .........
exciting stuff !!!!





........... Phil


I was wondering how long it would be till you werent worth talking to.
You made it longer then I expected.

NT

Lord Valve wrote in message ...
N. Thornton wrote:

I would go with an analogue meter rather than digital too: far more
use on Vs that arent entirely steady. Analogue meters do have serious
advantages.

You're a crackpot.

Let me guess - you're logged onto RAT/AGA with a Commodore 64
through a crank telephone, right? Using a 1kbaud modem?

Old **** is good ****, eh? Not when it comes to testgear, not
in my book.

If you want to look at a jittery voltage, a scope is far better for
doing so than an analog meter - the trace will respond way
faster than any mechanical meter movment, and it won't
bang the pin and trash itself if hit with a negative spike.

Lord Valve
Expert

Lord valve, if youre going to call yourself an expert, think a bit
more before posting. Your assumptions and guesses are kinda silly.

NT