Alright this thing is really getting on my nerves.

I want a list of conditions that the microcontroller in this unit can
detect which would cause it to turn off.

There is nothing wrong with the power amplifiers. At one time I had
this receiver running for two days with no problems whatsoever. At the
time, I believed there was a bad solder connection on the upper
amplifier board (the one containing all the voltage regulators and the
surround amplifiers), as barely tapping said board would cause the
power to turn off. I removed the board, resoldered everything large
(typical failure points) and reassembled. There was no change. I once
again removed the board, and resoldered a bunch more stuff (things
that looked cold/weak) and reassembled again. Now it shuts down EVERY
time. I press POWER, it turns on for about three seconds, then shuts
off. Sometimes the speaker output relays click on then back off
immediately at the same time as the power turns off, other times the
only click is the power supply relay.

The original failure caused the reverse diode on the power supply
relay to short. I replaced said diode.

Since I KNOW none of the power amplifiers are shorted, I accepted the
risk of bypassing the power supply relay. Apparently the computer in
this unit is smarter than me, since, even though it could no longer
actually turn off the power, it still blanked the display and stopped
responding to user input, as if it were off. The power amps do work in
this state, as I can inject a signal and drive speakers with them,
further proving that there is no actual fault to respond to. I am
strongly of the opinion that the microcontroller has been smoking
something it really shoud be sharing with the rest of us.

I want to know what conditions will trigger the computer to turn the
power off so that I can first try to figure out what is actually
wrong, or, failing that, trick it into minding its own business and
leaving me alone. Elsewise the whole thing is going to the basement
where I will ****stomp it and mangle it in ways Yamaha never imagined.

Please give me some input on this unit. I've never had this much BS
with an amplifier in my life, and after a similar experience with a
Yamaha powered mixer (TONS of bad soldering on the power supply board)
I am quickly losing any respect I ever had for Yamaha. Nice features
and would probably be good products IF THEY'D LEARN TO FREAKIN SOLDER.

wrote in message
...
Alright this thing is really getting on my nerves.

I want a list of conditions that the microcontroller in this unit can
detect which would cause it to turn off.

There is nothing wrong with the power amplifiers. At one time I had
this receiver running for two days with no problems whatsoever. At the
time, I believed there was a bad solder connection on the upper
amplifier board (the one containing all the voltage regulators and the
surround amplifiers), as barely tapping said board would cause the
power to turn off. I removed the board, resoldered everything large
(typical failure points) and reassembled. There was no change. I once
again removed the board, and resoldered a bunch more stuff (things
that looked cold/weak) and reassembled again. Now it shuts down EVERY
time. I press POWER, it turns on for about three seconds, then shuts
off. Sometimes the speaker output relays click on then back off
immediately at the same time as the power turns off, other times the
only click is the power supply relay.

The original failure caused the reverse diode on the power supply
relay to short. I replaced said diode.

Since I KNOW none of the power amplifiers are shorted, I accepted the
risk of bypassing the power supply relay. Apparently the computer in
this unit is smarter than me, since, even though it could no longer
actually turn off the power, it still blanked the display and stopped
responding to user input, as if it were off. The power amps do work in
this state, as I can inject a signal and drive speakers with them,
further proving that there is no actual fault to respond to. I am
strongly of the opinion that the microcontroller has been smoking
something it really shoud be sharing with the rest of us.

I want to know what conditions will trigger the computer to turn the
power off so that I can first try to figure out what is actually
wrong, or, failing that, trick it into minding its own business and
leaving me alone. Elsewise the whole thing is going to the basement
where I will ****stomp it and mangle it in ways Yamaha never imagined.

Please give me some input on this unit. I've never had this much BS
with an amplifier in my life, and after a similar experience with a
Yamaha powered mixer (TONS of bad soldering on the power supply board)
I am quickly losing any respect I ever had for Yamaha. Nice features
and would probably be good products IF THEY'D LEARN TO FREAKIN SOLDER.

I'm not the resident Yamaha guru on this board but the later Yamaha units
have a special key combination that you press to enable the diagnostic mode
which will tell you why it's shutting down or at least give you some general
info. For example it might say "power supply," or "dc offset." You would
need the service manual or some help from somebody who knows the exact key
combination and how to interpret the diagnostic menus.

Good luck.

--
David Farber
David Farber's Service Center
L.A., CA

I have googled various combinations of yamaha, diagnostics, receiver,
and the model number.

Apparently, on MOST Yamaha receivers, it is SET MENU and PROGRAM +
simultaneously at power-on.

That is not working on this receiver.

I have also learned that there are two shutdowns, one takes 3 seconds,
the other a half-second. This is definitely the three-second non-
serious shutdown mode.

Most of what I have found seems to indicate that the primary things
sensed are DC offset and the power supply rails. Every rail is well
within 10% of what's labeled next to it on the board, and the voltage
at the speaker-output-end of the emitter resistors is 0.00 on every
single amp channel.

I remain convinced that the problem is either in the surround amp /
voltage regulator board, or the computer itself.

I'm not the resident Yamaha guru on this board but the later Yamaha units
have a special key combination that you press *to enable the diagnostic mode
which will tell you why it's shutting down or at least give you some general
info. For example it might say "power supply," or "dc offset." You would
need the service manual or some help from somebody who knows the exact key
combination and how to interpret the diagnostic menus.

Good luck.

--
David Farber
David Farber's Service Center
L.A., CA- Hide quoted text -

- Show quoted text -

wrote in message
...
I have googled various combinations of yamaha, diagnostics, receiver,
and the model number.

Apparently, on MOST Yamaha receivers, it is SET MENU and PROGRAM +
simultaneously at power-on.

That is not working on this receiver.

I have also learned that there are two shutdowns, one takes 3 seconds,
the other a half-second. This is definitely the three-second non-
serious shutdown mode.

Most of what I have found seems to indicate that the primary things
sensed are DC offset and the power supply rails. Every rail is well
within 10% of what's labeled next to it on the board, and the voltage
at the speaker-output-end of the emitter resistors is 0.00 on every
single amp channel.

I remain convinced that the problem is either in the surround amp /
voltage regulator board, or the computer itself.

I'm not the resident Yamaha guru on this board but the later Yamaha units
have a special key combination that you press to enable the diagnostic
mode
which will tell you why it's shutting down or at least give you some
general
info. For example it might say "power supply," or "dc offset." You would
need the service manual or some help from somebody who knows the exact key
combination and how to interpret the diagnostic menus.

Good luck.

--
David Farber
David Farber's Service Center
L.A., CA- Hide quoted text -

- Show quoted text -

The last one I worked on was: "A/B/C/D/E", "Preset/Tuning --", while the
power button is being pressed.

--
David Farber
David Farber's Service Center
L.A., CA

The last one I worked on was: "A/B/C/D/E", "Preset/Tuning --", while the
power button is being pressed.

No luck.

wrote in message
...
The last one I worked on was: "A/B/C/D/E", "Preset/Tuning --", while the
power button is being pressed.

No luck.


This model is a little different. The following key combination will get
into diagnostic mode:

Press and hold "Input Mode" and "FM/AM" and while holding them, press the
Standby/On button.

You will see a brief display of the protection history, assuming the backup
cap is good, or the unit has not been unplugged since the last event.

Later Yamaha's will cancel the protect mode and stay on for you if you
continue to hold the first two keys for several seconds after pressing the
standby button. A red light will blink on the display to advise you that the
protection override is active. I think this also applies to yours, but I'm
not sure.

The shutoff you describe should be what is called DC PRT in the diagnostics,
which is a DC at the output of one or more channels.

Before you tell me you've already checked that - yes, I know. But there
could for example be a DC spike just at the moment the relay "should" fire.
This would trigger the Protect mode as well. Usually caused by a bad muting
transistor. The negative bias applied to the base of the defective
transistor will leak through and cause a momentary DC spike.

I gotta say, since it started shutting down consistently just after your
resoldering, I would recheck all my soldering. I happens to the best of
us...

You may e-mail me directly for the manual in PDF form - you'll probably need
WinRar to reassemble it.



and reverse the domain to read "sbcglobal". Notice there is an underscore
between my first and last name.


Mark Z.

This model is a little different. The following key combination will get
into diagnostic mode:
Press and hold "Input Mode" and "FM/AM" and while holding them, press the
Standby/On button.

"DC PRT: 0%"

Alright. DC offset, protect... 0%? 0% of what? And which power amp?
They all test as being fine...

Arrow points to "DVD/LD", which I'm assuming is significant since the
"CD" input is selected otherwise...

And holding the buttons down does not disable the protection function.

wrote in message
...
This model is a little different. The following key combination will get
into diagnostic mode:
Press and hold "Input Mode" and "FM/AM" and while holding them, press the
Standby/On button.

"DC PRT: 0%"

Alright. DC offset, protect... 0%? 0% of what? And which power amp?
They all test as being fine...

Arrow points to "DVD/LD", which I'm assuming is significant since the
"CD" input is selected otherwise...

And holding the buttons down does not disable the protection function.



I admit the % stuff is weird. The DVD/LD is just the default input for test
mode.

What I'd recommend is the old back-door power cord trick:

Rig a double-ended POLARIZED AC cord. Plug the receiver's own power cord
into one of it's switched outlets on the rear panel. Plug your double ended
cord into the other switched outlet. The free end now goes to your variac or
switched AC strip. You can bring up the variac and all the internal voltages
will stay up regardless of protection status. At this point you should be
able to tell with a simple voltage check which channel has your DC offset.

Like I said - the most common offender is a bad muting transistor for the
affected channel. Another possible culprit would be the low frequency
rolloff capacitor associated with the differential transistor pair for that
channel. This would be like C518 on the Main L. power amp channel.

Mark Z.

wrote in message
...
This model is a little different. The following key combination will get
into diagnostic mode:
Press and hold "Input Mode" and "FM/AM" and while holding them, press the
Standby/On button.

"DC PRT: 0%"

Alright. DC offset, protect... 0%? 0% of what? And which power amp?
They all test as being fine...

Arrow points to "DVD/LD", which I'm assuming is significant since the
"CD" input is selected otherwise...

And holding the buttons down does not disable the protection function.



Followup - rear panel ground was not qualified. OP re-installed the rear
panel screws, all is well.

Mark Z.