Mario Bros PCB Repair

I bought this board on ebay as untested and missing a potentiometer. Pots getting broken off of these early Nintendo boards seems to be a common problem.

First thing to do is find a suitable replacement as it's used for horizontal video placement, Bob Roberts sells nice replacements but I don't believe he ships outside the US anymore.

Finding 30K pots the right size isn't easy so I went for a 50k instead, I found some on ebay that looked more or less the right size.

After removing the unwanted bracket and bending the center pin to shape it fit nicely. 

 Now to power it up

 The title screen logo, character,enemy and pipe sprites were all missing.

Now I cheated a bit here as a quick google brings up quite a few posts and even a repair log with this exact issue. Channelmaniac's repair log was very helpful, I desoldered the Z80 DMA and ordered some off ebay.

 Soldered in a socket and fitted one of the Z80 DMAs from ebay and...

All the missing sprites returned.