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Adamfarber Adamfarber is offline
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Default Yamaha RX-V596 humming

Hi, I have a Yamaha RX-V596 home theater that has all of a sudden started to hum, unit is about 8 years old. . You can hear it in all the speakers, it is coming from the unit itself, anyone know what I can do? Thanks, Adam
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Mark Zacharias[_2_] Mark Zacharias[_2_] is offline
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Default Yamaha RX-V596 humming

"Adamfarber" wrote in message
...

Hi, I have a Yamaha RX-V596 home theater that has all of a sudden
started to hum, unit is about 8 years old. . You can hear it in all the
speakers, it is coming from the unit itself, anyone know what I can do?
Thanks, Adam




--
Adamfarber



If the Yamaha were actually producing hum, this would indicate most likely a
power supply problem.
Normally the Yamaha's protection circuit would shut it down in this
scenario.

Does the problem with ONLY the speakers and no other devices hooked up?

If not, perhaps a ground loop. This is not uncommon.

If so, maybe a main power supply capacitor open circuit - I'm not sure if
that would trigger the protect circuit.

Mark Z.

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Adamfarber Adamfarber is offline
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Quote:
Originally Posted by Mark Zacharias[_2_] View Post
"Adamfarber" wrote in message
...

Hi, I have a Yamaha RX-V596 home theater that has all of a sudden
started to hum, unit is about 8 years old. . You can hear it in all the
speakers, it is coming from the unit itself, anyone know what I can do?
Thanks, Adam




--
Adamfarber



If the Yamaha were actually producing hum, this would indicate most likely a
power supply problem.
Normally the Yamaha's protection circuit would shut it down in this
scenario.

Does the problem with ONLY the speakers and no other devices hooked up?

If not, perhaps a ground loop. This is not uncommon.

If so, maybe a main power supply capacitor open circuit - I'm not sure if
that would trigger the protect circuit.

Mark Z.
Hi Mark, I unhooked everything and hooked up a speaker to one of the outputs and listened to FM and I still heard the him. Thanks, Adam
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David Nebenzahl David Nebenzahl is offline
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Default Yamaha RX-V596 humming

On 6/13/2010 12:56 PM Adamfarber spake thus:

Hi Mark, I unhooked everything and hooked up a speaker to one of the
outputs and listened to FM and I still heard the him. Thanks, Adam


The "him"?
Oh, you must mean the "hymn".


--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)
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Adamfarber Adamfarber is offline
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[quote=David Nebenzahl;911263]On 6/13/2010 12:56 PM Adamfarber spake thus:

Hi Mark, I unhooked everything and hooked up a speaker to one of the
outputs and listened to FM and I still heard the him. Thanks, Adam


The "him"?
Oh, you must mean the "hymn".


Whoops, meant HUM, thanks, Adam


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Mark Zacharias[_2_] Mark Zacharias[_2_] is offline
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Default Yamaha RX-V596 humming

"Adamfarber" wrote in message
...

'Mark Zacharias[_2_ Wrote:
;911215']"Adamfarber" wrote in
message
...-

Hi, I have a Yamaha RX-V596 home theater that has all of a sudden
started to hum, unit is about 8 years old. . You can hear it in all

the
speakers, it is coming from the unit itself, anyone know what I can

do?
Thanks, Adam




--
Adamfarber-



If the Yamaha were actually producing hum, this would indicate most
likely a
power supply problem.
Normally the Yamaha's protection circuit would shut it down in this
scenario.

Does the problem with ONLY the speakers and no other devices hooked
up?

If not, perhaps a ground loop. This is not uncommon.

If so, maybe a main power supply capacitor open circuit - I'm not sure
if
that would trigger the protect circuit.

Mark Z.


Hi Mark, I unhooked everything and hooked up a speaker to one of the
outputs and listened to FM and I still heard the him. Thanks, Adam




--
Adamfarber



Well, you would need a schematic at this point, which brings up the
question, are you a technical person and able to read the schematic?

Mark Z.

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Fred[_12_] Fred[_12_] is offline
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Default Yamaha RX-V596 humming


"Adamfarber" wrote in message ...

David Nebenzahl;911263 Wrote:
On 6/13/2010 12:56 PM Adamfarber spake thus:
-
Hi Mark, I unhooked everything and hooked up a speaker to one of the
outputs and listened to FM and I still heard the him. Thanks, Adam-


The "him"?
Oh, you must mean the "hymn".


Whoops, meant HUM, thanks, Adam


Most likely a cap in one of the low voltage supplies has failed, feeding unfiltered
DC to a regulator which cannot maintain smooth output voltage because the input
is going to zero 120 times a second.

You have to be a technician with troubleshooting skills, experience with AV receivers,
test equipment and service information to fix this. Assuming that's not you, the unit
needs to go to a Yamaha warranty station for repair (Yamaha's warranty stations have
access not just to service manuals but also to confidential service bulletins, and more
importantly they have access to the technical staff at Yamaha, which is the only really
competent technical staff in the business). I can call Allen at Yamaha, give him the
model number, and he'll tell me what the problem is and how to fix it because he and his
staff know their equipment that well.

Obviously, I work for a Yamaha warranty station. That's the only company we still do
warranty audio work for, because it's the only one with a staff that knows a damn thing
about their product. Well, them and McIntosh, but there are no Mac dealers around here,
so they don't figure they need a warranty station here (Reno, NV).

Fred

--
Adamfarber



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Adamfarber Adamfarber is offline
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[quote='Fred[_12_];911292']"Adamfarber" wrote in message ...

David Nebenzahl;911263 Wrote:
On 6/13/2010 12:56 PM Adamfarber spake thus:
-
Hi Mark, I unhooked everything and hooked up a speaker to one of the
outputs and listened to FM and I still heard the him. Thanks, Adam-


The "him"?
Oh, you must mean the "hymn".


Whoops, meant HUM, thanks, Adam


Most likely a cap in one of the low voltage supplies has failed, feeding unfiltered
DC to a regulator which cannot maintain smooth output voltage because the input
is going to zero 120 times a second.

You have to be a technician with troubleshooting skills, experience with AV receivers,
test equipment and service information to fix this. Assuming that's not you, the unit
needs to go to a Yamaha warranty station for repair (Yamaha's warranty stations have
access not just to service manuals but also to confidential service bulletins, and more
importantly they have access to the technical staff at Yamaha, which is the only really
competent technical staff in the business). I can call Allen at Yamaha, give him the
model number, and he'll tell me what the problem is and how to fix it because he and his
staff know their equipment that well.

Obviously, I work for a Yamaha warranty station. That's the only company we still do
warranty audio work for, because it's the only one with a staff that knows a damn thing
about their product. Well, them and McIntosh, but there are no Mac dealers around here,
so they don't figure they need a warranty station here (Reno, NV).

Fred


Hey Fred, thanks for the post. I am somewhat handy, if someone could narrow down which part(s) may be suspect I will replace them so any help you could give me would be GREAT! Adam
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Fred[_12_] Fred[_12_] is offline
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Default Yamaha RX-V596 humming


"Adamfarber" wrote in message ...

'Fred[_12_ Wrote:
;911292']"Adamfarber" wrote in
message ...-

David Nebenzahl;911263 Wrote:-
On 6/13/2010 12:56 PM Adamfarber spake thus:
--
Hi Mark, I unhooked everything and hooked up a speaker to one of

the
outputs and listened to FM and I still heard the him. Thanks,

Adam--

The "him"?
Oh, you must mean the "hymn".


Whoops, meant HUM, thanks, Adam--


Most likely a cap in one of the low voltage supplies has failed,
feeding unfiltered
DC to a regulator which cannot maintain smooth output voltage because
the input
is going to zero 120 times a second.

You have to be a technician with troubleshooting skills, experience
with AV receivers,
test equipment and service information to fix this. Assuming that's
not you, the unit
needs to go to a Yamaha warranty station for repair (Yamaha's warranty
stations have
access not just to service manuals but also to confidential service
bulletins, and more
importantly they have access to the technical staff at Yamaha, which is
the only really
competent technical staff in the business). I can call Allen at
Yamaha, give him the
model number, and he'll tell me what the problem is and how to fix it
because he and his
staff know their equipment that well.

Obviously, I work for a Yamaha warranty station. That's the only
company we still do
warranty audio work for, because it's the only one with a staff that
knows a damn thing
about their product. Well, them and McIntosh, but there are no Mac
dealers around here,
so they don't figure they need a warranty station here (Reno, NV).

Fred


Hey Fred, thanks for the post. I am somewhat handy, if someone could
narrow down which part(s) may be suspect I will replace them so any
help you could give me would be GREAT! Adam


I'll check the service manual & bulletins when I get back to work (I'm out with
the flu at the moment, and don't know for sure when that will be; sometime in
the next day or three) and see if I can give you any worth while advice. Some
models are damn near impossible to take apart and get back together without
the manual. There can be 20 or more cables that have to be unplugged and
then plugged back in to the right socket on the right board on reassembly, just
to get to the board(s) you need to work on. I'm assuming you want to try a
shotgun approach and just replace every cap that could be causing the problem.
It'd take a 'scope to figure out what cap *is* the problem.

Watch this thread; I'll post again when I have some information for you.

Fred


--
Adamfarber



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Adamfarber Adamfarber is offline
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[quote='Fred[_12_];911336']"Adamfarber" wrote in message ...

'Fred[_12_ Wrote:
;911292']"Adamfarber" wrote in
message ...-

David Nebenzahl;911263 Wrote:-
On 6/13/2010 12:56 PM Adamfarber spake thus:
--
Hi Mark, I unhooked everything and hooked up a speaker to one of

the
outputs and listened to FM and I still heard the him. Thanks,

Adam--

The "him"?
Oh, you must mean the "hymn".


Whoops, meant HUM, thanks, Adam--


Most likely a cap in one of the low voltage supplies has failed,
feeding unfiltered
DC to a regulator which cannot maintain smooth output voltage because
the input
is going to zero 120 times a second.

You have to be a technician with troubleshooting skills, experience
with AV receivers,
test equipment and service information to fix this. Assuming that's
not you, the unit
needs to go to a Yamaha warranty station for repair (Yamaha's warranty
stations have
access not just to service manuals but also to confidential service
bulletins, and more
importantly they have access to the technical staff at Yamaha, which is
the only really
competent technical staff in the business). I can call Allen at
Yamaha, give him the
model number, and he'll tell me what the problem is and how to fix it
because he and his
staff know their equipment that well.

Obviously, I work for a Yamaha warranty station. That's the only
company we still do
warranty audio work for, because it's the only one with a staff that
knows a damn thing
about their product. Well, them and McIntosh, but there are no Mac
dealers around here,
so they don't figure they need a warranty station here (Reno, NV).

Fred


Hey Fred, thanks for the post. I am somewhat handy, if someone could
narrow down which part(s) may be suspect I will replace them so any
help you could give me would be GREAT! Adam


I'll check the service manual & bulletins when I get back to work (I'm out with
the flu at the moment, and don't know for sure when that will be; sometime in
the next day or three) and see if I can give you any worth while advice. Some
models are damn near impossible to take apart and get back together without
the manual. There can be 20 or more cables that have to be unplugged and
then plugged back in to the right socket on the right board on reassembly, just
to get to the board(s) you need to work on. I'm assuming you want to try a
shotgun approach and just replace every cap that could be causing the problem.
It'd take a 'scope to figure out what cap *is* the problem.

Watch this thread; I'll post again when I have some information for you.

Fred

Shall do Fred, thanks again for trying! Adam


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Chuck Chuck is offline
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Default Yamaha RX-V596 humming

On Mon, 14 Jun 2010 10:11:08 -0700, "Fred"
wrote:


"Adamfarber" wrote in message ...

David Nebenzahl;911263 Wrote:
On 6/13/2010 12:56 PM Adamfarber spake thus:
-
Hi Mark, I unhooked everything and hooked up a speaker to one of the
outputs and listened to FM and I still heard the him. Thanks, Adam-

The "him"?
Oh, you must mean the "hymn".


Whoops, meant HUM, thanks, Adam


Most likely a cap in one of the low voltage supplies has failed, feeding unfiltered
DC to a regulator which cannot maintain smooth output voltage because the input
is going to zero 120 times a second.

You have to be a technician with troubleshooting skills, experience with AV receivers,
test equipment and service information to fix this. Assuming that's not you, the unit
needs to go to a Yamaha warranty station for repair (Yamaha's warranty stations have
access not just to service manuals but also to confidential service bulletins, and more
importantly they have access to the technical staff at Yamaha, which is the only really
competent technical staff in the business). I can call Allen at Yamaha, give him the
model number, and he'll tell me what the problem is and how to fix it because he and his
staff know their equipment that well.

Obviously, I work for a Yamaha warranty station. That's the only company we still do
warranty audio work for, because it's the only one with a staff that knows a damn thing
about their product. Well, them and McIntosh, but there are no Mac dealers around here,
so they don't figure they need a warranty station here (Reno, NV).

Fred

--
Adamfarber



Allen is still around at Yamaha? I'd have thought he would have
retired years ago. Chuck
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Fred[_12_] Fred[_12_] is offline
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Default Yamaha RX-V596 humming


"Chuck" wrote in message ...
On Mon, 14 Jun 2010 10:11:08 -0700, "Fred"
wrote:


"Adamfarber" wrote in message ...

David Nebenzahl;911263 Wrote:
On 6/13/2010 12:56 PM Adamfarber spake thus:
-
Hi Mark, I unhooked everything and hooked up a speaker to one of the
outputs and listened to FM and I still heard the him. Thanks, Adam-

The "him"?
Oh, you must mean the "hymn".


Whoops, meant HUM, thanks, Adam


Most likely a cap in one of the low voltage supplies has failed, feeding unfiltered
DC to a regulator which cannot maintain smooth output voltage because the input
is going to zero 120 times a second.

You have to be a technician with troubleshooting skills, experience with AV receivers,
test equipment and service information to fix this. Assuming that's not you, the unit
needs to go to a Yamaha warranty station for repair (Yamaha's warranty stations have
access not just to service manuals but also to confidential service bulletins, and more
importantly they have access to the technical staff at Yamaha, which is the only really
competent technical staff in the business). I can call Allen at Yamaha, give him the
model number, and he'll tell me what the problem is and how to fix it because he and his
staff know their equipment that well.

Obviously, I work for a Yamaha warranty station. That's the only company we still do
warranty audio work for, because it's the only one with a staff that knows a damn thing
about their product. Well, them and McIntosh, but there are no Mac dealers around here,
so they don't figure they need a warranty station here (Reno, NV).

Fred

--
Adamfarber



Allen is still around at Yamaha? I'd have thought he would have
retired years ago. Chuck


He's about the last of the old gang still there, and someone's being
groomed to take his place. Probably won't be there a year from now,
but I think he's hanging in until his replacement is fully up to speed.

Fred


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Fred[_12_] Fred[_12_] is offline
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Default Yamaha RX-V596 humming


"Adamfarber" wrote in message ...

'Fred[_12_ Wrote:
;911336']"Adamfarber" wrote in
message ...-

'Fred[_12_ Wrote:-
;911292']"Adamfarber" wrote in
message ...--

David Nebenzahl;911263 Wrote:-
On 6/13/2010 12:56 PM Adamfarber spake thus:
--
Hi Mark, I unhooked everything and hooked up a speaker to one

of-
the-
outputs and listened to FM and I still heard the him. Thanks,-
Adam---

The "him"?
Oh, you must mean the "hymn".


Whoops, meant HUM, thanks, Adam---

Most likely a cap in one of the low voltage supplies has failed,
feeding unfiltered
DC to a regulator which cannot maintain smooth output voltage

because
the input
is going to zero 120 times a second.

You have to be a technician with troubleshooting skills, experience
with AV receivers,
test equipment and service information to fix this. Assuming

that's
not you, the unit
needs to go to a Yamaha warranty station for repair (Yamaha's

warranty
stations have
access not just to service manuals but also to confidential service
bulletins, and more
importantly they have access to the technical staff at Yamaha, which

is
the only really
competent technical staff in the business). I can call Allen at
Yamaha, give him the
model number, and he'll tell me what the problem is and how to fix

it
because he and his
staff know their equipment that well.

Obviously, I work for a Yamaha warranty station. That's the only
company we still do
warranty audio work for, because it's the only one with a staff

that
knows a damn thing
about their product. Well, them and McIntosh, but there are no Mac
dealers around here,
so they don't figure they need a warranty station here (Reno, NV).

Fred


Hey Fred, thanks for the post. I am somewhat handy, if someone

could
narrow down which part(s) may be suspect I will replace them so any
help you could give me would be GREAT! Adam--


I'll check the service manual & bulletins when I get back to work (I'm
out with
the flu at the moment, and don't know for sure when that will be;
sometime in
the next day or three) and see if I can give you any worth while
advice. Some
models are damn near impossible to take apart and get back together
without
the manual. There can be 20 or more cables that have to be unplugged
and
then plugged back in to the right socket on the right board on
reassembly, just
to get to the board(s) you need to work on. I'm assuming you want to
try a
shotgun approach and just replace every cap that could be causing the
problem.
It'd take a 'scope to figure out what cap *is* the problem.

Watch this thread; I'll post again when I have some information for
you.

Fred

Shall do Fred, thanks again for trying! Adam


Hi Adam,

Finally got back to work today, and had a look at the service manual.

First, you want to check the + & - voltages to the output stage. To do this,
you'll need a Digital Multi-Meter (DVM). You want to check the voltage from
chassis ground to the collectors of any two adjacent output transistors in the
power amp with the unit powered up. Be careful not to let the meter probe
touch anything else while doing this, or you'll get a big arc and blown fuses or
worse. The exact voltage will depend on your line voltage and the setting of
the 4/8 ohm switch on the rear panel; the range is approximately +/- 40V to
+/- 70V. What's important is that the + voltage equals the - voltage within a
volt or two. If the voltages are not nearly equal, the main filter cap for the
lower of the two voltages is probably bad. Those caps are on the Main (3)
board at the left rear of the unit.

It the unit passes that test, one of the following capacitors is probably bad,
and without a scope the only way to proceed is to obtain replacements for
all of them and replace them all.

On the Power (5) board, in the left front of the unit, mounted on the power xfmr
secondary: C451 & 452, 330uf @ 50V. C453 & 455, 4700uf @ 25V. C458 &
463, 4700uf @ 16V. Lastly, on the Main (3) board previously mentioned, C760
& 761, 100uf @ 50V.

If replacing these caps doesn't eliminate the hum, or if all this sounds way over
your head, it's either off to a warranty station with the unit, or off to the
electronics store in search of a replacement. I would expect repair to cost
between $100 & $200. This is a pretty old unit; the service manual was printed
on paper. These days everything is in PDF on the computer.

Hope this helps,

Fred



--
Adamfarber



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Fred[_12_] Fred[_12_] is offline
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Default Yamaha RX-V596 humming


"Zack" wrote in message ...
Fred wrote:

If replacing these caps doesn't eliminate the hum, or if all this sounds
way over your head, it's either off to a warranty station with the unit,
or off to the
electronics store in search of a replacement. I would expect repair to
cost
between $100 & $200. This is a pretty old unit; the service manual was
printed
on paper. These days everything is in PDF on the computer.


Fred,
if you think that is old, I have an AX-630 which drops one or both channels
intermittently. During the dropout, the audio is low and distorted with
mostly just buzzing. Increasing the volume sometimes breaks through the
distortion and the problem goes away for a time. The unit has an AST pack,
so replacing just the amp (which otherwise sounds great when it is working)
would require new speakers.

Any ideas what might be wrong with it? Reseating the wires external and
internal does not seem to result in a fix. Mostly happens while using the
tuner, a TX-400U - which had a bad solder joint on the output that was
fixed a few years ago.



Hey Zack,

You say it mostly happens while using the tuner. I assume that's because
you mostly listen to the radio. But if it also happens when listening to other
sources like CD, the problem has to be in the amp. So here's a plan:

First thing to do is attack the switches & controls with Caig De-Oxit D5.
Push button switches often require removal of the front panel so you can
spray de-oxit into the switch where the shaft from the button enters the
switch. Spray and then cycle the switch 8 or 10 times.

Pots only need de-oxit if they scratch or cut out when rotated from limit to
limit. If they're doing that, they need to have the de-oxit sprayed in where
the terminals come out. It often helps to put a 90 degree bend in the last
inch or two of the spray tube so you can aim the spray up or down and into
the pot where it's connected to the pc board. After spraying the pot, turn it
back and forth, limit to limit, at least a half dozen times. Sometimes you
have to pull the pc board out of the unit to get access to the pots. ;-(

De-oxit is powerful stuff. You don't have to flood the area for it to work - a
quick blast will do ya if it's aimed right. Given that both channels are cutting
out individually, it's about a 98% chance the de-oxit is going to solve your
problem if you do it right.

But if that doesn't do it, then it's a matter of finding the bad connection by
visual inspection, mechanical shock (a tap here, a tap there), thermal shock
(freeze spray, heat gun), and/or good old fashioned signal tracing with a
scope or signal tracer while the unit's misbehaving. Comparing the same
point in the bad channel with the working channel will tell you if what you're
seeing or hearing is OK or not.

Keep in mind it's possible the bad connection is inside a transistor or IC -
freeze spray is good for finding that kind of problem.

It really helps to have a schematic so you can see where the signal goes
next if de-oxit doesn't fix it. Given its age, you can probably find the service
manual for your amp on the internet in pdf form, possibly for a few $ from
one of the many service manual purveyors out there these days. Google is
your friend.

Good luck,

Fred


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Default Yamaha RX-V596 humming


"Zack" wrote in message ...
Fred wrote:


"Zack" wrote in message
...
if you think that is old, I have an AX-630 which drops one or both
channels
intermittently. During the dropout, the audio is low and distorted with
mostly just buzzing. Increasing the volume sometimes breaks through the
distortion and the problem goes away for a time. The unit has an AST
pack, so replacing just the amp (which otherwise sounds great when it is
working) would require new speakers.

Any ideas what might be wrong with it? Reseating the wires external and
internal does not seem to result in a fix. Mostly happens while using
the tuner, a TX-400U - which had a bad solder joint on the output that
was fixed a few years ago.



Hey Zack,

You say it mostly happens while using the tuner. I assume that's because
you mostly listen to the radio. But if it also happens when listening to
other
sources like CD, the problem has to be in the amp. So here's a plan:

First thing to do is attack the switches & controls with Caig De-Oxit D5.
Push button switches often require removal of the front panel so you can
spray de-oxit into the switch where the shaft from the button enters the
switch. Spray and then cycle the switch 8 or 10 times.


This sounds like a good idea.

Pots only need de-oxit if they scratch or cut out when rotated from limit
to
limit. If they're doing that, they need to have the de-oxit sprayed in


The controls are in remarkably good shape and don't have any noise when
rotated. Kudos to Yamaha on that front.

De-oxit is powerful stuff. You don't have to flood the area for it to
work - a
quick blast will do ya if it's aimed right. Given that both channels are
cutting out individually, it's about a 98% chance the de-oxit is going to
solve your problem if you do it right.

But if that doesn't do it, then it's a matter of finding the bad
connection by visual inspection, mechanical shock (a tap here, a tap
there), thermal shock (freeze spray, heat gun), and/or good old fashioned
signal tracing with a
scope or signal tracer while the unit's misbehaving. Comparing the same
point in the bad channel with the working channel will tell you if what
you're seeing or hearing is OK or not.

Keep in mind it's possible the bad connection is inside a transistor or IC
- freeze spray is good for finding that kind of problem.

It really helps to have a schematic so you can see where the signal goes
next if de-oxit doesn't fix it. Given its age, you can probably find the
service manual for your amp on the internet in pdf form, possibly for a
few $ from
one of the many service manual purveyors out there these days. Google is
your friend.


Ironically, Yamaha has since released a DSP amp with the same ID that has
loads of chips and gagdetry my unit does not have. Makes Google harder to
use.

Thanks for the tips, they are something to try!


Zack,

I don't know what Yamaha's policy is concerning service info for non-warranty
servicers; I've been doing warranty work for them since they first went into the
consumer audio business. You might be able to get the service manual from
Yamaha for a few bucks if you wind up needing it. It's worth a phone call or an
email to find out.

Fred




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jackster jackster is offline
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Quote:
Originally Posted by Fred[_12_] View Post
"Zack" wrote in message ...
Fred wrote:


"Zack" wrote in message
...
if you think that is old, I have an AX-630 which drops one or both
channels
intermittently. During the dropout, the audio is low and distorted with
mostly just buzzing. Increasing the volume sometimes breaks through the
distortion and the problem goes away for a time. The unit has an AST
pack, so replacing just the amp (which otherwise sounds great when it is
working) would require new speakers.

Any ideas what might be wrong with it? Reseating the wires external and
internal does not seem to result in a fix. Mostly happens while using
the tuner, a TX-400U - which had a bad solder joint on the output that
was fixed a few years ago.



Hey Zack,

You say it mostly happens while using the tuner. I assume that's because
you mostly listen to the radio. But if it also happens when listening to
other
sources like CD, the problem has to be in the amp. So here's a plan:

First thing to do is attack the switches & controls with Caig De-Oxit D5.
Push button switches often require removal of the front panel so you can
spray de-oxit into the switch where the shaft from the button enters the
switch. Spray and then cycle the switch 8 or 10 times.


This sounds like a good idea.

Pots only need de-oxit if they scratch or cut out when rotated from limit
to
limit. If they're doing that, they need to have the de-oxit sprayed in


The controls are in remarkably good shape and don't have any noise when
rotated. Kudos to Yamaha on that front.

De-oxit is powerful stuff. You don't have to flood the area for it to
work - a
quick blast will do ya if it's aimed right. Given that both channels are
cutting out individually, it's about a 98% chance the de-oxit is going to
solve your problem if you do it right.

But if that doesn't do it, then it's a matter of finding the bad
connection by visual inspection, mechanical shock (a tap here, a tap
there), thermal shock (freeze spray, heat gun), and/or good old fashioned
signal tracing with a
scope or signal tracer while the unit's misbehaving. Comparing the same
point in the bad channel with the working channel will tell you if what
you're seeing or hearing is OK or not.

Keep in mind it's possible the bad connection is inside a transistor or IC
- freeze spray is good for finding that kind of problem.

It really helps to have a schematic so you can see where the signal goes
next if de-oxit doesn't fix it. Given its age, you can probably find the
service manual for your amp on the internet in pdf form, possibly for a
few $ from
one of the many service manual purveyors out there these days. Google is
your friend.


Ironically, Yamaha has since released a DSP amp with the same ID that has
loads of chips and gagdetry my unit does not have. Makes Google harder to
use.

Thanks for the tips, they are something to try!


Zack,

I don't know what Yamaha's policy is concerning service info for non-warranty
servicers; I've been doing warranty work for them since they first went into the
consumer audio business. You might be able to get the service manual from
Yamaha for a few bucks if you wind up needing it. It's worth a phone call or an
email to find out.

Fred
Sorry for reviving an old thread, but I have the exact same amplifier with the
exact same problem. I have already obtained the capacitors mentioned earlier in
this thread (C451 & 452, 330uf @ 50V. C453 & 455, 4700uf @ 25V. C458 & 463,
4700uf @ 16V. C760 & 761, 100uf @ 50V) and the service manual for this amplifier.

My question is this: the C760 and 761 capacitors in my amplifier are 100uf @ 63V
instead of 50V. The service manual agrees with what Fred said, it also states that
C760 & 761 are 100uf @ 50V. Can I still replace the capacitors with the ones I
bought (100uf @ 50V) or should I buy new ones rated at 63V? I would like to trust
what the service manual says and just pop in the 50V capacitors even though the
board currently has 63V ones.

Last edited by jackster : January 25th 11 at 11:30 PM
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