Ba5000 Buffer Board Variations?

[HDJR808]

Hello, since it looks like there might be some variation during production on the BA5000 I'm hoping someone might be able to confirm whether a couple of the components on the buffer board of my ba5k are the correct values. This amp came off the line in 1976.

I'm trying to track down some distortion in the left channel that is showing up on the scope, and have traced it back to the buffer board. Since I'm going to pull the board, I figure now is the time to recap it. But in comparing the schematic vs. the actual board before ordering caps, I've found that the buffer board layout differs from the service manual that is available on HiFiEngine.

The schematic indicates C604 as being a 63v 47uf, which is present, but the board in mine also has a C605, not on the schematic, that is a 50v 47uf cap. Also the 5w R618 on the schematic is listed as 270ohm while this resistor on my board is 150ohm. Also, in what appears to be a slightly different layout, on my board R616 is mounted on end as opposed to horizontally as in the few photos I've found online.

This board is a little buried, so until I pull it, it's tough to determine whether the caps look to be original.

Any info would be appreciated- Herb

 

[lugom]

HDJR808, You are correct.....I also have problem (Hissing sound on one of the Channel) please search in this web as I have forgotten under what category I put it in. I have compared my Buffer to the one advertised by Sansui Part shop and is quite Different in
the Layout. I have contacted one of our country,s top Technician (I am from Malaysia) and he advised me to change ALL the Big Black Nichicon Power Capacitors (22000 Uf 80V) which I have not done yet as I believe they are Not the Culprit.
I will update you on mine tomorrow (the Caps Position and its value mfd)

 

[johnny_fever]

I bought that board from the Sansui Parts Shop. It was identical to the buffer board I had In my 1975 BA-5K

 

[HDJR808]

Thanks everybody-

Fever, the photo of the Sansui Parts Shop board that you bought matches the one that I am working on. This is from '76.

Do you recall if the replacement board matched your original?

This is the layout on a '75 board:

which matches the schematic and pcb:

Lugom, it sounds like this is the board that you have.

My only real concern, since the schematic I have doesn't match my board, is that I am correct on the values of C604 and C605 and not just reproducing someones previous possibly mistaken installation.

And of course figuring out the reason for what I get on the scope at the output of f-2520:

:sigh:

 

[HDJR808]

Do you recall if the replacement board matched your original?

Sorry Fever, I vapor locked and asked you the question that you had already answered...

 

[johnny_fever]

No Problem. Yes my board had the 2 caps behind the volume pot. I can probably dig up some pics If you want. Fever

 

[HDJR808]

Photos would be great- thanks.

 

[johnny_fever]

Msg me your email address and I will send you some big pics. Fever