Help with Power on yamaha rx-596 AV receiver (capacitors?)

[11higgy]

Been trying miserably to diagnose this problem and learn about the the capacitors. So, I have a Yamaha rx-596 AV receiver. For years it has run perfectly. Got back from a trip and it won't power on. Read that it is usually the capacitor running out of juice on the power board. I will provide picture of this area to see if anyone knows better, but will also ask a couple specific problems beyond the obvious, how can I get the power back.

The couple capacitors located on the power board:

I understand the nanofarad readings (This one is 103, meaning 10 nanos). What is meaning of the difference between J and K lettering as in "tolerance" +-5% vs +-10%? Is interchanging these ok or harmful?

How do I figure out the voltage on these when they are not listed on the piece? What voltage is ok for the ones on the power? The only ones available online range around 400-650.

What is the meaning of M85 on the capacitor? What does this indicate?

I am asking these questions to figure out a safe replacement for these to troubleshoot the power issue. I am willing to solder and desolder to figure it out. If you know any answers, or even better, know what I am doing wrong in my approach, please help. This is my baby, had it for almost a decade and it's a beaut. It is simply not powering on. No clicks, nothing, no response from the on/off button.

[R_J]

Re: Help with Power on yamaha receiver (capacitors?)

It won't be a problem with those small caps. First check if you have Standby voltage. you should have +14 volts across C151 on the sub power board or +12 volts on plug CB108, Thats the small board where the power cord connects, the plug is white with 4 wires, from the rear of the amp the wires are: ground, ground, +12v, Power on

[11higgy]

Re: Help with Power on yamaha receiver (capacitors?)

2 things: There's only a C152 on the board (the brown cylinder on the side farthest from the back), don't know how to test that without disassembling the whole board.

And

I accidentally touched the other wire while metering and it sparked!! I must've shorted it. It's not reading anything now, damnit. What is that part called? The CB108 (it is actually CB109 on this board). Gonna have to find several parts now. No idea what to look up. Thanks for the help by the way.

[R_J]

Re: Help with Power on yamaha receiver (capacitors?)

You likely shorted the standby 12 volts and blew the standby regulator transistor or shorted something in the amp somehere, Are you sure this is a repair you can do or maybe better to take it to a repair shop?
C151 is the electrolytic capacitor next to the transformer.

If you decide to continue, at least download the service manual.

At this point you need to unplug the CB10x cable from the main board (BE CAREFULL) so you don't damage the connector, then remove the standby board and check the components. If you got a spark you likely "had" 12 volts standby and the fault is somewhere else.
I would suggest removing the plug from the main board and see if the 12 volts comes back, (try not to short it) If it does, the standby power supply is ok and you damaged something on the operation board.

[redwire]

Re: Help with Power on yamaha receiver (capacitors?)

It looks like a linear regulator circuit, not the mosfet (standby) circuit and small capacitor which is a problem on other Yamaha receivers. Here, it's not C152 to blame.
edit: noticed nothing for parts on the PC board (i.e unpopulated C149) and a jumper J291 seems to bypass the need for a 12V regulator?
Jumper J291 (=no +12V standby regulator) used for USA, Canada, Australia but not in "general" versions.

[ChaosLegionnaire]

Re: Help with Power on yamaha receiver (capacitors?)

higgy, use electrical insulating tape to cover the wire u are testing while taking it out (remove the tape once the wire is clear of the other wires and are no longer in danger of shorting) or cover the other wires with the tape. such a simple and cheap item will save u a ton of headaches from accidental shorts frying stuff!

[R_J]

Re: Help with Power on yamaha receiver (capacitors?)

I did'nt look at which board was used in U/C so the transistors are not used and bypassed by J291, The short may have damaged D125, or maybe burnt a trace, (or opened the transformer)
Check if you still have 14vdc standby voltage on J291. If not, check the diode D125

[PeteS in CA]

Re: Help with Power on yamaha receiver (capacitors?)

What is the meaning of M85 on the capacitor? What does this indicate?

It could be a date or source code. That capacitor is a .01uF, 5% part, probably metallized polyester film.

[dickd]

Re: Help with Power on yamaha receiver (capacitors?)

I have a RX-V595 receiver with the On then off issue and read about the c233 cap.
Mine does not have the C233 cap and am thinking do i have the same issue but with my 2 caps at location C837 and C842 being replaced will this be a similar fix.

[madan1]

Re: Help with Power on yamaha receiver (capacitors?)

I have a RX-V595 receiver with the On then off issue and read about the c233 cap.
Mine does not have the C233 cap and am thinking do i have the same issue but with my 2 caps at location C837 and C842 being replaced will this be a similar fix.

No point in changing that capacitors, it is different design.