Yamaha RX-V863

[ga70gto]

Re: Yamaha RX-V863

By back probing the line connector I have apprx 125 volts in. Once the relay closes it supplies voltage through the two onboard fuses, one to the switched outlets, one to the main power transformer. I measured apprx. 120v at the fuses but plugging in an incandescent desk lamp to either of the switched outlets kills the voltage to 0. measuring the two leads of the primary side of the transformer I have line voltage, measuring across the secondary side I have 14.2v. the resistance of the primary side is 730 ohms, the secondary side 16 ohms.

I decided to do a bizarre test and desoldered the "contact" side of the relay. In fact the relay is not closing I had no continuity across it and I still had the strange voltage at the fuses when line voltage is applied to the board though but I don't think that's anything to worry about.

[budm]

Re: Yamaha RX-V863

BTW, the amperage is dictated by the resistance of the load being connected to that 120 VAC source, the higher the resistance the less current flow.
If you really have 120VAC through the relay contacts that goes to the HOT and Neutral pins of the connector that goes to the primary winding of the main power transformer when the power transformer is not connected, but then it drops down to 0 VAC when the transformer is connected, that means you have high resistance in the power line going to the power transformer.
You will have to check the ACV on the input side of the relay and the output side of the relay, and the traces and the connections all the way to the power transformer primary winding.
Service manual:
https://cdn.badcaps-static.com/pdfs/...4561d91119.pdf

[budm]

Re: Yamaha RX-V863

First of all when check the incoming AC to the unit, do not use the chassis GND as the GND ref for your meter, the correct way to measure the incoming AC is between LINE (HOT, or PHASE) and NEUTRAL, then between LINE after the fuse and Neutral, then LINE after the relay output contact and Neutral.
The relay on that standby board is just used for switching AC (LINE) to the main power transformer, and the switched OUTLET if it has one.
So there has to be measurement.

[ga70gto]

Re: Yamaha RX-V863

one more thing, I had described this unit as an "amplifier", really it's a receiver/amplifier. Sorry if this caused any confusion.

[ga70gto]

Re: Yamaha RX-V863

Hey Bud, thanks for responding. I checked voltage from chassis ground to the fuses, both fuses are good, I had voltage at both ends, lol. Problem is as per the pic once you plug anything in to the rear receptacles the voltage goes away or you might say goes to "0". It 'goes away when you plug in an incandescent desk lamp, if I plug in a phone charger the voltage ranges from about 50 to 90 volts and per the phone the charger turns off and on. My guess being turns on when the voltage reads 90v. It acts like a 12v DC car wiring system that's has lost it's ground.I had hoped for dirty contacts in the relay so I ordered one from Mouser, no go, same effect. Also, I was able to find a duplicate power supply on ebay and it has the same characteristics. it was my thinking that maybe this board is some how 'smart", if it doesn't see whatever it's looking for it won't work properly. I thought maybe this would be an easy fix since it doesn't do anything at all vs.some kind of intermittent problem. I've though about jumping power directly to the large power transformer but don't want to do that just yet. I was hoping to find some resistance values for the different power transformer leads but no luck yet.

as always thanks for your time,
ga70gto

[budm]

Re: Yamaha RX-V863

When you said you have 120Vac at the fuse, how did you measure the Voltage? You measure Voltage the two ends of the fuse? You may also have bad relay contacts.

[ga70gto]

Yamaha rx-v863 amplifier does not power on at all, no clicks. It also will not enter self diagnostic mode. There are several threads on the net for replacing a capacitor on the "sub power" (?) board but my board does not have that capacitor. there is also a thread detailing the replacement of a thermal fuse in the transformer but mine does not check "open". There is a small transformer on the board that provides 12 volts, it seems to power up and close a relay on that board which then provides line voltage (110v) to the main transformer. This relay does close and then 110v is available to the transformer when not plugged in but there is no amperage to do any work. I removed the sub power board from the unit, checked the voltage at the fuses and received apprx. 110v but as soon as you plug anything into the rear sockets of the board the voltage goes away thus my assuming there's no amperage to do any "work". I'd appreciate a shove in the right direction, the service manual is available for download on the net.

thanks in advance,
ga70gto