Page 1 of 1

Wanted pin-out for Blackstar/Marshall 7-pin pots

Posted: 12 Aug 2020, 21:54
by microbailey
Hi everyone. I'm dismantling and tracing a Blackstar Fly 3 amplifier (see thread here: viewtopic.php?f=2&t=30681 and here:http://www.midboost.com/workbench/blackstar-fly-3) and I am looking for the pin-out for the 7-pin PCB pots used by Blackstar - pictures from above and below PCB follow:
Blackstar_PCB_pot.jpg
Blackstar_PCB_pot_under.jpg
I know this is a dual gang (tandem) pot and I think it is the same pot used by Marshall for Master Volume in some modern amps (DSL 401 ?)

Does anyone have a pin-out for this pot?
I have a feeling one pin is a dummy leaving 6 pins for the 2x tandem pots.
I could desolder a pot and then resistance test but thought I'd ask here first.

I did find the Bourns pot range which matches what Blackstar use, but no 7-pin tandem I'm afraid.

Re: Wanted pin-out for Blackstar/Marshall 7-pin pots

Posted: 13 Aug 2020, 01:43
by ppluis0
Hi microbailey,

Try this pin assignments and see if make sense in your tracing:
Image

Cheers,
Jose

Re: Wanted pin-out for Blackstar/Marshall 7-pin pots

Posted: 13 Aug 2020, 15:45
by microbailey
:thumbsup Aha! Yes that looks promising. I'll plug it into the schematic I have so far and see if it makes sense.
After a bit more research I think the pots are Alps not Bourns.

Thanks Jose

Re: Wanted pin-out for Blackstar/Marshall 7-pin pots

Posted: 16 Aug 2020, 17:23
by microbailey
I tried the pinout suggested by ppluis0 in my traced schematics and it fits. This is confirmed using a multimeter to measure resistance between the 7-pins, assuming the pinouts given in https://sc01.alicdn.com/kf/HTB1HJD8vLiS ... DcpXa7.jpg.

Searching the web I also found
Alps_7pin_pot.JPG
Alps_7pin_pot.JPG (19.19 KiB) Viewed 1416 times
on the Apls website - which agrees with ppluis0

Thanks for that - I can press on with tracing the Blackstar EQ section now I now how these 7-pin pots are wired :D