Akai S01 hum / noise fix

[Circuitbenders]

Heres a quick tip for anyone searching for a fix to the annoying hum on their Akai S01. I've seen this problem on about 50% of S01's i've worked on. What will happen is that you'll get a changing level of annoying background hum that seems to depend on how many sections are lit on the 3 character LED display for its severity.

This is caused by some dodgy grounding on the power supply board. If you remove the PSU board you'll notice a star formation in solder on the underside of the screw hole on the top left, next to where it says 'CAUTION'. This is meant to ground the PSU board to the case via the PCB spacer, but on a badly humming machine you'll probably find that the solder has crumbled away causing a bad ground connection. Just stick a metal washer between the board and the metal spacer underneath it and all the hum should disappear.

[draftwork]

Hi, i think i have the same problem that you explain. Can you tell me where is it exactly? 1, 2 or 3
sorry im french..

Thanks man!

[draftwork]

I just found the star solder. So i placed a metal washer between the board and the metal spacer. The hum is less noisy but it still there.. Do you know why?

Thanks for your answer

Terry

[Circuitbenders]

You might have to do the same for the grounding on the main board.
Or actually reflow the solder on the grounding star that you just added the washer too.

[draftwork]

What do you mean on the main board?
I reflowed the solder, it still there...

[Circuitbenders]

erm, the main board. As in, the big board that is the main board.
I'm not sure how else to describe it.

Its got to be grounded to the case somehow. Maybe it has the same problem.