Yamaha receiver.

RX-V975A no display, relay clicks, & shuts down. Very hard unit to work on. You have to scrap these units, just to solder a few bad connections. Can't find anything online. Anyone work on one of these? Thanks, Dani.

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Are you talking about the standby relay ? Unit looks like it's going to come on ok, then just drops back to standby ? I have had a similar problem to this on several Yammies, and it has proved to be bad contacts on the standby relay. Relay closes. Bad contacts arc and spit. Rails don't come up as the uP expects, so it shuts it back down. Worth a try before getting all technical with it.


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Arfa Daily

Doesn't look like a valid model number. Could it be


Those of us who have had the (mis)fortune of having to work on surround receivers these past few years have mostly learned to work around the obstacles.

You can rig a double-ended AC cord (use ONLY polarized ends, and make sure they match end-to-end).

Plug the receiver's own AC cord into one of it's switched outlets. Plug your double-ended cord into the other switched outlet. This will bypass the relay. If everything pretty much works normally, the relay problem is confirmed.

Remember: The AC cord polarity must match or there will be MAJOR sparks, since the AC line would be shorted if they were reversed. For this reason, only an experienced tech really should attempt this.

Mark Z.

Reply to
Mark D. Zacharias

There are 2 protection circuits,

1 shuts down instanly upon turn on if there's a major problem like a faulty/blown amp channel- to stop other damage occuring.

The second trips at about 5 seconds, indicating a less serious problem like a low voltage rail missing....ie 5v regulator gone.

Does it trip instantly.... or after 5 secs... I suspect from the fact the display isn't coming on, its instant.

If so check for a +/- 50 volts appearing on any of the big (white?) resistors just in front of the big transistors on the heat sink- at the instant of turn on....you only get 1/2 sec to see. Normally you won't get any voltage. If a channels gone... it needs specialist fixing.


Reply to
Cliff Top


This method can also be used to check DC offsets and all internal power supply voltages, regardless of protection status. For this reason, it is important to make sure you don't have a blown channel or some other high current draw before going too far with this method. A variac is most useful in this regard.

Mark Z.

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Mark D. Zacharias

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