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Guest
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 Posted:
Tue Dec 28, 2004 4:31 pm Post subject:
Yamaha R-900 Receiver Protective circuit relay question |
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I have a Yamaha R-900 Receiver that has worked flawlessly up until
about a week ago.
About one out of four times that I switch it "on" the protective
circuit relay does not engage.
Also, if I leave it on for several hours, the receiver will shut down.
Any suggestions?
Thanks,
Mark
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west
Guest
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| Posted:
Wed Dec 29, 2004 4:43 am Post subject:
Re: Yamaha R-900 Receiver Protective circuit relay question |
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<dbacks@attglobal.net> wrote in message
news:1104233503.476131.248220@f14g2000cwb.googlegroups.com...
| Quote: | I have a Yamaha R-900 Receiver that has worked flawlessly up until
about a week ago.
About one out of four times that I switch it "on" the protective
circuit relay does not engage.
Also, if I leave it on for several hours, the receiver will shut down.
Any suggestions?
Thanks,
Mark
|
You may have a component that breaks down with heat. Use a hair blow dryer
in the pertinent area. When the receiver shuts off, spray the area with
coolant, using the nozzle insert tube to focus on individual components. A
little practice and you can become a pro troubleshooting thermal problems.
Good luck and remember the aforementioned is only 1 possibility, but I
believe a good starting point. Good Luck and Happy New Year.
Cordially,
west |
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Carroll Conklin
Guest
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| Posted:
Wed Dec 29, 2004 7:28 am Post subject:
Re: Yamaha R-900 Receiver Protective circuit relay question |
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This is not quite a tube issue but I think I can help you. The offset
voltage adjust is set to borderline operation. i.e. there is approximately
50mV at one of the speaker outputs. Yamaha had two pots per channel for
adjustment. One was for idle current and the other for this offset adjust.
Your speaker protection circuit is sensing this offset and turning on and
off depending how bad it is.
Carroll
<dbacks@attglobal.net> wrote in message
news:1104233503.476131.248220@f14g2000cwb.googlegroups.com...
| Quote: | I have a Yamaha R-900 Receiver that has worked flawlessly up until
about a week ago.
About one out of four times that I switch it "on" the protective
circuit relay does not engage.
Also, if I leave it on for several hours, the receiver will shut down.
Any suggestions?
Thanks,
Mark
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Chris Hornbeck
Guest
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| Posted:
Wed Dec 29, 2004 8:25 am Post subject:
Re: Yamaha R-900 Receiver Protective circuit relay question |
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On 28 Dec 2004 03:31:43 -0800, dbacks@attglobal.net wrote:
| Quote: | I have a Yamaha R-900 Receiver that has worked flawlessly up until
about a week ago.
About one out of four times that I switch it "on" the protective
circuit relay does not engage.
Also, if I leave it on for several hours, the receiver will shut down.
Any suggestions?
|
Resolder all connections for both output "modules" and the
common driver "module". The solder joints are definitely bad,
and if you're very lucky, the "modules" won't be.
Power supply regulator pass transistors, too. Basically,
*LOOK* at the PC board with a very critical eye.
Also, search and destroy (scrape away) any hot-glue you can
find *anywhere*. It's become partially conductive and somewhat
corrosive over the past two decades. And check *under* the
electrolytic capacitors, wherever you see it on the outsides.
Sometimes the old tube stuff doesn't seem so old does it?
Good fortune,
Chris Hornbeck
"They'd meet at the Tout Va Bien."
-JLG, _Bande a part_, 1964 |
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Guest
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| Posted:
Wed Dec 29, 2004 4:29 pm Post subject:
Re: Yamaha R-900 Receiver Protective circuit relay question |
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Hi Carroll,
Sorry if a question about a solid state receiver seems a bit off topic
for this "valve" ng...
But there is a wealth of talent, knowledge and experience posting to
this ng.
Due to the age of this receiver, I was/am hoping that someone would
have the information to point me in the right direction.
Most of these "tube gurus" have forgotten more than I will ever know
about tube gear, and some of the same tube guys also serviced early
solid state audio equipment.
I do appreciate any and all input,
Thanks,
Mark |
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Mark D. Zacharias
Guest
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| Posted:
Wed Dec 29, 2004 6:15 pm Post subject:
Re: Yamaha R-900 Receiver Protective circuit relay question |
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Bad idea suggesting this person adjust his own amp with no training or test
equipment.
Yamaha's trigger at about 1.2 volts. If there's this much offset, the amp
needs service - period.
The problem could be a bad cap in the feedback circuit, we've seen this
before.
Mark Z.
Authorized Yamaha servicer
"Carroll Conklin" <aconklin@rcn.com> wrote in message
news:l6-dnWtI4-GQcUzcRVn-hg@rcn.net...
| Quote: | This is not quite a tube issue but I think I can help you. The offset
voltage adjust is set to borderline operation. i.e. there is approximately
50mV at one of the speaker outputs. Yamaha had two pots per channel for
adjustment. One was for idle current and the other for this offset adjust.
Your speaker protection circuit is sensing this offset and turning on and
off depending how bad it is.
Carroll
dbacks@attglobal.net> wrote in message
news:1104233503.476131.248220@f14g2000cwb.googlegroups.com...
I have a Yamaha R-900 Receiver that has worked flawlessly up until
about a week ago.
About one out of four times that I switch it "on" the protective
circuit relay does not engage.
Also, if I leave it on for several hours, the receiver will shut down.
Any suggestions?
Thanks,
Mark
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Guest
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| Posted:
Fri Dec 31, 2004 7:57 pm Post subject:
Re: Yamaha R-900 Receiver Protective circuit relay question |
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Hi Mark.
Your point about a novice is a good one. I have no intention of
tampering with something as nice as this unit, and possibly causing
more harm than good.
I have a couple of "junkers" that would make better learning fodder...
However, I do have a couple of friends that serviced Vacuum tube/early
solid state equipment, and they have helped me in the past get audio
gear up and running.
They have been more than gracious in their aid to help, but I hate to
impose on them.
So, by posting on this ng, I can get a better better grasp of
electronic circuitry, and narrow down what the trouble with a unit
might be.
I can learn, as well as do the legwork in gathering schematics,
knowledge, and parts.
| Quote: | From what very little electronic circuitry experience that I have had,
I suspected a leaky/faulty capacitor, (possibly more than one) causing |
an "unbalanced" signal back to the relay.
By the way, I had a Marantz that had almost identical symptoms, and it
turned out to be one of the rail 10000uf 63v capacitors that was
faulty.
I am wondering if the problem with this unit might also be one or both
of the the rail caps???
I am searching for a schematic for this unit, and hopefully will be
able to have some idea what the problem is prior to asking one of my
buddies to help.
Thanks
Mark |
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