Greetings,

I have a Yamaha RX-V995 Amplifier that, at any given time, will just
shut off. All I have to do is power it back on and sometimes it will
work for hours and other times it will shut off right away. It would
not hold the last settings and I found the memory cap to be defective,
you know, leaky cap syndrome. That was a 4.7F 5.5V cap. at any rate,
I went over it with a fine tooth comb looking for loose solder joints
and other caps that might be leaky, found and re-soldered a few
cracked joints on a regulator board buried in the bottom of this
beast, all else looks fine. It does have some power relays for the
speaker outputs and B+ power. I remember replacing those on the
fisher amps years ago... I was wondering if anyone has worked on one
of these and what you might of found. This unit is loaded and looks
clean sadly; I do not have a schematic. Nothing leaked into it from
the top. It doesn't appear to have smoked any transistors or
resistors, at least none of the major 'let the smoke out' components.
The power to the proc seems steady and there isn't any noticeable
ripple on any of the power buss lines that I have found. I really
haven't checked for DC showing up on the outputs as of yet, not really
sure how the safety circuits work in this unit. It doesn't run too hot
when on for hours at a time. I thought finding and replacing the 4.7F
cap would have taken care of it, but still shuts down. To reply to me
directly just take caps out of my address.

Thanks in advance,

Markus

"Markus" wrote in message
...
Greetings,

I have a Yamaha RX-V995 Amplifier that, at any given time, will just
shut off. All I have to do is power it back on and sometimes it will
work for hours and other times it will shut off right away. It would
not hold the last settings and I found the memory cap to be defective,
you know, leaky cap syndrome. That was a 4.7F 5.5V cap. at any rate,
I went over it with a fine tooth comb looking for loose solder joints
and other caps that might be leaky, found and re-soldered a few
cracked joints on a regulator board buried in the bottom of this
beast, all else looks fine. It does have some power relays for the
speaker outputs and B+ power. I remember replacing those on the
fisher amps years ago... I was wondering if anyone has worked on one
of these and what you might of found. This unit is loaded and looks
clean sadly; I do not have a schematic. Nothing leaked into it from
the top. It doesn't appear to have smoked any transistors or
resistors, at least none of the major 'let the smoke out' components.
The power to the proc seems steady and there isn't any noticeable
ripple on any of the power buss lines that I have found. I really
haven't checked for DC showing up on the outputs as of yet, not really
sure how the safety circuits work in this unit. It doesn't run too hot
when on for hours at a time. I thought finding and replacing the 4.7F
cap would have taken care of it, but still shuts down. To reply to me
directly just take caps out of my address.

Thanks in advance,

Markus


The nature of this failure suggests to me that there is a speaker wire
shorting intermittently.

Yamaha's have diagnostics built in that can tell us whether it was an
over-current (shorted speaker wire) situation, a DC offset problem on an amp
channel, a power supply problem, etc.

You may e-mail me direct if you would like some help with this; I am an
authorized Yamaha servicer.

email to:



and reverse the domain name.

Mark Z.

Mark,

This is my Cousins amp, I've been in the repair business for over 30+
years. If it has a wire coming out of it I will at least look at it.
I work on TV's that have tons of built in diagnostics; the days of
trim pots seem to be gone. I really appreciate your help.
Speaker testing
I thought of that and ran over at his house last week with my
ohmmeter, all lines were in the 3ohm range. This is using a Fluke
digital VOM. I do have an impedeance meter that I could dig out to do
some testing on the speakers didn't take it with me. I thought that
one of his cats might of bit through the wiring. I ran the wires with
my hand and found nothing of note wrong with the wires jackets. Due
to the age of the unit and finding that mem cap leaking I could only
think that, perhaps, there is some leaky i.e. 10uf@50V cap in the
power amps pre driver section pulling the DC offset up. Is there some
sort of built in Diags? He couldn't find the manual; however, I
haven't seen any owners manuals have too much in the way of technical
information. Sometimes too much info for the average consumer is
dangerous. I get VCRs in that the user opened up to try to fix it and
frankly I would rather turn those ones down.

I looked at all the boards for cracks and they really look clean. I
blew out all of the dust so that I could get a good look at them, for
the age of the unit it really is clean. He has it mounted in a
cabinet that has a glass door on the front of it.

Thanks again for the reply,


Markus

On Fri, 09 Sep 2005 10:34:18 GMT, "Mark D. Zacharias"
wrote:


"Markus" wrote in message
.. .
Greetings,

I have a Yamaha RX-V995 Amplifier that, at any given time, will just
shut off. All I have to do is power it back on and sometimes it will
work for hours and other times it will shut off right away. It would
not hold the last settings and I found the memory cap to be defective,
you know, leaky cap syndrome. That was a 4.7F 5.5V cap. at any rate,
I went over it with a fine tooth comb looking for loose solder joints
and other caps that might be leaky, found and re-soldered a few
cracked joints on a regulator board buried in the bottom of this
beast, all else looks fine. It does have some power relays for the
speaker outputs and B+ power. I remember replacing those on the
fisher amps years ago... I was wondering if anyone has worked on one
of these and what you might of found. This unit is loaded and looks
clean sadly; I do not have a schematic. Nothing leaked into it from
the top. It doesn't appear to have smoked any transistors or
resistors, at least none of the major 'let the smoke out' components.
The power to the proc seems steady and there isn't any noticeable
ripple on any of the power buss lines that I have found. I really
haven't checked for DC showing up on the outputs as of yet, not really
sure how the safety circuits work in this unit. It doesn't run too hot
when on for hours at a time. I thought finding and replacing the 4.7F
cap would have taken care of it, but still shuts down. To reply to me
directly just take caps out of my address.

Thanks in advance,

Markus


The nature of this failure suggests to me that there is a speaker wire
shorting intermittently.

Yamaha's have diagnostics built in that can tell us whether it was an
over-current (shorted speaker wire) situation, a DC offset problem on an amp
channel, a power supply problem, etc.

You may e-mail me direct if you would like some help with this; I am an
authorized Yamaha servicer.

email to:



and reverse the domain name.

Mark Z.

The Yamaha monitoring circuit tests all the psu rails and therefore any rail
going high/low in voltage by more than say 20% will cause the unit to trip.
There are 2 severities however. If the power trips so rarely it'll be
difficult to know whether its the 1/2 sec (serious) or 3 sec (not so..)
mode.
I recently had a smaller Yamaha in recently with just this symptom. turned
out to be a leaky diode causing a low -25v rail for the FDP drive. In any
other manufacturers unit the screen would be off (or dim as in this case)
but here it causes a trip.
The diagnostics don't really help with an error code of 16% reading for the
psu rail... normal value 23%.... weird values but basically correct at
16/23rds of the rails normal value.
Your problem will doubtless be one of the rails but with so many you'll just
have to test each in turn. Thats a bit tricky in the few seconds you get
I've also had a 5v reg go s/c so that 10v is put through to other areas
without tripping !!

Diagnostics is usually hold 2 buttons like set menu & prog+ on front panel
then bring out of standby.
There are 2 diag modes, one where the protection is removed... this can be
very dangerous if you have a serious rail fault and could cause untold extra
damage so needs to be used wisely.

If you need the pdf manual, I can send it when back off my hols..
regards
Andrew


"Markus" wrote in message
...
Mark,

This is my Cousins amp, I've been in the repair business for over 30+
years. If it has a wire coming out of it I will at least look at it.
I work on TV's that have tons of built in diagnostics; the days of
trim pots seem to be gone. I really appreciate your help.
Speaker testing
I thought of that and ran over at his house last week with my
ohmmeter, all lines were in the 3ohm range. This is using a Fluke
digital VOM. I do have an impedeance meter that I could dig out to do
some testing on the speakers didn't take it with me. I thought that
one of his cats might of bit through the wiring. I ran the wires with
my hand and found nothing of note wrong with the wires jackets. Due
to the age of the unit and finding that mem cap leaking I could only
think that, perhaps, there is some leaky i.e. 10uf@50V cap in the
power amps pre driver section pulling the DC offset up. Is there some
sort of built in Diags? He couldn't find the manual; however, I
haven't seen any owners manuals have too much in the way of technical
information. Sometimes too much info for the average consumer is
dangerous. I get VCRs in that the user opened up to try to fix it and
frankly I would rather turn those ones down.

I looked at all the boards for cracks and they really look clean. I
blew out all of the dust so that I could get a good look at them, for
the age of the unit it really is clean. He has it mounted in a
cabinet that has a glass door on the front of it.

Thanks again for the reply,


Markus

On Fri, 09 Sep 2005 10:34:18 GMT, "Mark D. Zacharias"
wrote:


"Markus" wrote in message
.. .
Greetings,

I have a Yamaha RX-V995 Amplifier that, at any given time, will just
shut off. All I have to do is power it back on and sometimes it will
work for hours and other times it will shut off right away. It would
not hold the last settings and I found the memory cap to be defective,
you know, leaky cap syndrome. That was a 4.7F 5.5V cap. at any rate,
I went over it with a fine tooth comb looking for loose solder joints
and other caps that might be leaky, found and re-soldered a few
cracked joints on a regulator board buried in the bottom of this
beast, all else looks fine. It does have some power relays for the
speaker outputs and B+ power. I remember replacing those on the
fisher amps years ago... I was wondering if anyone has worked on one
of these and what you might of found. This unit is loaded and looks
clean sadly; I do not have a schematic. Nothing leaked into it from
the top. It doesn't appear to have smoked any transistors or
resistors, at least none of the major 'let the smoke out' components.
The power to the proc seems steady and there isn't any noticeable
ripple on any of the power buss lines that I have found. I really
haven't checked for DC showing up on the outputs as of yet, not really
sure how the safety circuits work in this unit. It doesn't run too hot
when on for hours at a time. I thought finding and replacing the 4.7F
cap would have taken care of it, but still shuts down. To reply to me
directly just take caps out of my address.

Thanks in advance,

Markus


The nature of this failure suggests to me that there is a speaker wire
shorting intermittently.

Yamaha's have diagnostics built in that can tell us whether it was an
over-current (shorted speaker wire) situation, a DC offset problem on an
amp
channel, a power supply problem, etc.

You may e-mail me direct if you would like some help with this; I am an
authorized Yamaha servicer.

email to:



and reverse the domain name.

Mark Z.

"Cliff Top" wrote in message
...
The Yamaha monitoring circuit tests all the psu rails and therefore any
rail
going high/low in voltage by more than say 20% will cause the unit to
trip.
There are 2 severities however. If the power trips so rarely it'll be
difficult to know whether its the 1/2 sec (serious) or 3 sec (not so..)
mode.
I recently had a smaller Yamaha in recently with just this symptom.
turned
out to be a leaky diode causing a low -25v rail for the FDP drive. In any
other manufacturers unit the screen would be off (or dim as in this case)
but here it causes a trip.
The diagnostics don't really help with an error code of 16% reading for
the
psu rail... normal value 23%.... weird values but basically correct at
16/23rds of the rails normal value.
Your problem will doubtless be one of the rails but with so many you'll
just
have to test each in turn. Thats a bit tricky in the few seconds you get
I've also had a 5v reg go s/c so that 10v is put through to other areas
without tripping !!

Diagnostics is usually hold 2 buttons like set menu & prog+ on front
panel
then bring out of standby.
There are 2 diag modes, one where the protection is removed... this can be
very dangerous if you have a serious rail fault and could cause untold
extra
damage so needs to be used wisely.

If you need the pdf manual, I can send it when back off my hols..
regards
Andrew



Sounds like you're an authorized servicer as well. Where are you? I already
sent him the manual - he should have it by now.

Mark Z.
(Wichita, KS.)

Thanks for all of your help, I'll let you know how I make out.

take care and have a great weekend,

Markus,

On Sat, 10 Sep 2005 21:04:28 GMT, "Mark D. Zacharias"
wrote:


"Cliff Top" wrote in message
...
The Yamaha monitoring circuit tests all the psu rails and therefore any
rail
going high/low in voltage by more than say 20% will cause the unit to
trip.
There are 2 severities however. If the power trips so rarely it'll be
difficult to know whether its the 1/2 sec (serious) or 3 sec (not so..)
mode.
I recently had a smaller Yamaha in recently with just this symptom.
turned
out to be a leaky diode causing a low -25v rail for the FDP drive. In any
other manufacturers unit the screen would be off (or dim as in this case)
but here it causes a trip.
The diagnostics don't really help with an error code of 16% reading for
the
psu rail... normal value 23%.... weird values but basically correct at
16/23rds of the rails normal value.
Your problem will doubtless be one of the rails but with so many you'll
just
have to test each in turn. Thats a bit tricky in the few seconds you get
I've also had a 5v reg go s/c so that 10v is put through to other areas
without tripping !!

Diagnostics is usually hold 2 buttons like set menu & prog+ on front
panel
then bring out of standby.
There are 2 diag modes, one where the protection is removed... this can be
very dangerous if you have a serious rail fault and could cause untold
extra
damage so needs to be used wisely.

If you need the pdf manual, I can send it when back off my hols..
regards
Andrew



Sounds like you're an authorized servicer as well. Where are you? I already
sent him the manual - he should have it by now.

Mark Z.
(Wichita, KS.)