Broken Yamaha RX-A700

[CoopedUp]

I would really like to figure this one out so if anyone else has input it would be appreciated

[temperance]

I remember repairing a very similar amplifier four or five years ago.

The problem with this amplifiers is the stand-by power supply. Next to the power inlet, you will see a printed circuit board with a CMOS40xx something IC, a relays, some passives,... The circuit in question is fed by a capacitive power supply. The cap has gone bad and the start-up circuit fails to switch on properly because the power supply voltage drops almost to zero.

Can you post a top view of the board located next to the power inlet? Then I can tell you which capacitor you have to replace.


When ordering a capacitor: be sure to replace the capacitor with an X type capacitor. Otherwise a surge on the mains might destroy the complete circuit.

[mzacharias]

I remember repairing a very similar amplifier four or five years ago.

The problem with this amplifiers is the stand-by power supply. Next to the power inlet, you will see a printed circuit board with a CMOS40xx something IC, a relays, some passives,... The circuit in question is fed by a capacitive power supply. The cap has gone bad and the start-up circuit fails to switch on properly because the power supply voltage drops almost to zero.

Can you post a top view of the board located next to the power inlet? Then I can tell you which capacitor you have to replace.


When ordering a capacitor: be sure to replace the capacitor with an X type capacitor. Otherwise a surge on the mains might destroy the complete circuit.

This only applies to the 220/240 volt models.

[mzacharias]

I remember repairing a very similar amplifier four or five years ago.

The problem with this amplifiers is the stand-by power supply. Next to the power inlet, you will see a printed circuit board with a CMOS40xx something IC, a relays, some passives,... The circuit in question is fed by a capacitive power supply. The cap has gone bad and the start-up circuit fails to switch on properly because the power supply voltage drops almost to zero.

Can you post a top view of the board located next to the power inlet? Then I can tell you which capacitor you have to replace.


When ordering a capacitor: be sure to replace the capacitor with an X type capacitor. Otherwise a surge on the mains might destroy the complete circuit.

And by the way, this particular capacitor is in series with the line, not across it. X rating would be fine, but not required. The original part certainly was not so rated.

[temperance]

X rated capacitors will last longer because the cap still has to withstand surges although with a resistor in series. That's the reason why the original capacitors loose their capacitance.

https://www.vishay.com/doc?28153

Page 2.

An X rated capacitor is a better approach when the full circuit is unknown.

[CoopedUp]

This is the board I think you are referring to. The thing will power on in it's protection circut is bypassed and it gives me an error code.

[CoopedUp]

I now have a dc prt 255 h. it used to be ps2 prt 255 so I still dont know what to do

[temperance]

Interesting, this amplifier doesn't have the cap dropper but a fly-back power supply based on a power integrations TOP switch.


You might want to take a look at the schematic:
https://elektrotanya.com/yamaha_rx-v667_htr-6063_rx-a700.pdf/download.html#dl

You will find a description of what The PS2_PRT means on Page 50. Some more on page 74.


I think you should be able to repair the amp with this information. (search the PDF for PS2)

Regards

[CoopedUp]

I have the manual and all that I have scratched my way through just about everything