Author Topic: Broken Yamaha RX-A700  (Read 3232 times)

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Offline CoopedUp

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Re: Broken Yamaha RX-A700
« Reply #50 on: June 18, 2019, 03:04:12 pm »
I would really like to figure this one out so if anyone else has input it would be appreciated
 

Offline temperance

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Re: Broken Yamaha RX-A700
« Reply #51 on: June 19, 2019, 08:55:31 pm »
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.
 

Offline mzacharias

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Re: Broken Yamaha RX-A700
« Reply #52 on: June 22, 2019, 11:41:31 pm »
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.
 

Offline mzacharias

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Re: Broken Yamaha RX-A700
« Reply #53 on: June 22, 2019, 11:43:40 pm »
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.
 

Offline temperance

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Re: Broken Yamaha RX-A700
« Reply #54 on: June 23, 2019, 08:28:25 pm »
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.
 

Offline CoopedUp

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Re: Broken Yamaha RX-A700
« Reply #55 on: June 24, 2019, 05:16:13 pm »
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.
 

Offline CoopedUp

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Re: Broken Yamaha RX-A700
« Reply #56 on: June 24, 2019, 05:53:28 pm »
I now have a dc prt 255 h. it used to be ps2 prt 255 so I still dont know what to do
 

Offline temperance

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Re: Broken Yamaha RX-A700
« Reply #57 on: June 24, 2019, 10:43:52 pm »
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
 

Offline CoopedUp

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Re: Broken Yamaha RX-A700
« Reply #58 on: June 24, 2019, 10:45:27 pm »
I have the manual and all that I have scratched my way through just about everything
 


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