Sansui F-2088 differences

I got lucky last week and found out a QRX-777 here in italy with 4 Sansui speakers for only 300€ (about 320$)

I cleaned all the external parts and tested it. Works like a charm, QS, SQ, CD-4 (except someone removed the lamp)

Today I decided to improve separation of QS just moving the internal pots on the F-2088, I already did this on the other QRX-7001 I have.

Somewhere I remembered I had a spare F-2088 board so I decided to swap it and setup that board too. Surprisingly it didn't sound good as the other one, but it works. I took it off the amp and replaced it with the original, but it took me a second to notice a difference on the board. Though they both are F-2088 the PCBs are a little different.

Can you spot the difference?

Top is taken from the 777


Rear PCBs




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Just a quick look shows the top board has 2 brown wires that the bottom doesn't. I can see the traces in those areas look a bit different.

The model of the PCB are different as well
There's no proof on which came first but it looks like the QRX-777 came later.
Name on the 777 PCB is GCMK-29EHB while the other is GMK-29EHB
the brand is SANSUI-1 on the 777 against SANSUI.

I knew 777 and 7001 had different CD-4 subcarrier boards, but I didn't knew it could have different version of the same board

Looks to be quite a few changes in the board. My guess is last year of manufacture.......quite possibly the same board used in last year of manufacture 8001 & 9001's.. It would be interesting to see if that is true.

You guys with late '75 & '76 models, check your cards and please post your findings.

I just acquired a QRX-8001. It needs a lot of cleaning and possibly a cabinet rebuild. But the interesting thing is it has the same F-2088 board as the one that came out of the 777. I think it is from 11-76 i.e 23611 etc. How does this figure in your current hypothesis of the evolution of the F-2088 board?