Shoot Out repair log

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Apr 172016

Got this game for a repair.

Game booted without problems but it was missing music and sound effects.

The amplifier was working correctly as I could hear the typical white noise coming out of the speakers.





As you can see, the game is upside down and checking with Mame there is no flip dipswitch so unfortunately is one of the few horizontal arcade games which has the screen upside down (the other that I know is Athena from SNK).

Another thing you should have noticed is the copyright…..some smart italian arcade owner has hacked the original date from 1985 to 1987 to make the game looking newer….it’s unfortunately very common in Italy.

back to the real problem, I checked with my portable amplifier the input to the operational amplifier and there was no sound.

That meant that either the DAC was faulty of something in the sound circuit logic.

The DAC is a YM3014


The SD pin is the output of the YM2203 which is a digital waveform so normally you cannot check with an amp if the YM2203 is working or not.

The only thing you can hear is white noise but there is a trick:  compare the breaks between melodies (example, between coin up and start game), so the YM2203 should also stop orstart again to output signals.

With this trick I could confirm that the DAC was faulty.

Replacing the YM3014 with a good one fixed the problem as expected.



Robocop 2 repair log

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Jun 242015

The game was working fine but you could hear only the sound fx, not the music.

Usually these kind of issues are related to either the DAC or the operational amplifier connected to the FM sound chip.

I used my external amplifier to probe the output of an operation amplifier and I could hear perfectly the music.

After checking for interrupted lines I noticed a missing cap.

Bridging the two pins restored the music.

Easy job!

Foto 15-05-15 18 02 59


Foto 15-05-15 18 02 49

Robocop repair log #1

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Jun 152011

Bought a Robocop board from the AO forums. Seller says the jump button didn’t work.
Doing a visual inspection revealed a burnt out track just off pin 23 on the edge connector, which is button 2, in this case, the jump button.


I repaired the trace but still no joy with getting the controls back.
Further inspection showed that the custom resistor array had burnt out. This resistor array has some modified characteristics compared a normal array, it passes an input out to a different pin and has a few other differences too. As I don’t have any spares of the custom array I decided to use a standard one pulled from a scrap board.


To make this work I had to short pins 6 and 7 together and 8 and 9 together. These are for button 1 and button 2.
The board is now fully working but ill keep an eye out for an original replacement part to fit.

Funky Jet repair log

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Sep 072010

The game had way too much yellow on screen, almost impossible to see anything other than yellow.
I Traced blue/green circuit back to palette RAMs K8 and K9. Both looked fine on the scope so had to desolder the pair of them. The RAM at K8 failed a test . Socketed and replaced the faulty RAM with a 2018 and tested.

All working fine