First arcade pcb repair - Cabal bootleg pcb

Ok, so here goes my first repair blog..

I traded 3 Nintendo n64 controllers for 3 arcade pcb's, 2 were faulty, this one working but no sound.. 

Think this is a good repair to start with

It works fine, but no sound, so lets start the detective work

I already know that the amps on these old boards have a tendency to go bad, so i pulled up a datasheet for this amp.. An uPC1241H

Ok, so pin #6 is audio out, lets test that with the scope

That looks fine, i hooked up a external speaker to Ground and pin #6 and i got good sound.. So it looks like the amp is fine..

The board have had som repair and mods, somewere in the past.. Like the mod from track ball to joystick (with looks easyer on this bootleg) but the pcb had also some poorly done repair , like this cap,hooked directly to the amp

But wait, that is pin #6, the output!! Lets trace that backwards..

By tracking it back to the edge connector, i realised that speaker + and - were reversed, and since my super gun dont use jamma - for the sound but just ground due to the scart cable i use, i Got no sound.. So i quickled reversed the bad repair, and fitted the right cap

And now Cabal play with all the sounds!

Job done, for my first pcb repair.. I know my Master and mentor (Elgen) will be proud :)

By the Way, if you like arcade repair done by at true repair wiz, go check out his blog at 

http://elgensrepairs.blogspot.dk