MVS 4 slot with issues

Heya ll,

First post. Just joined hoping to find some help.

Picked up a 4 slot cab not working. Machine booted to crosshatch of death. Removed the battery (on advice from here) cleaned the alkali up with vinegar and repaired a couple traces.

Powered game up and it booted but there was no sound and every game locked up in every slot after random amounts of time. No sound in tests, from speakers or headphones.

Wired board into a test bench / supergun and 12v shut down forcing the power supply into protection mode. Removed the ha13001 and system no longer shut down. Replaced ha13001 with new one and system boots with sound! Getting somewhere.

All games freeze after a minute or so after starting and exhibit small black dots on screen. Increase voltage to 5.5v and games stops freezing as often.

Games mostly run but with a lot of black dots on screen, like mosquitos flying about and also concerned about increased 5v levels because 12v climbs even more, to like 14.5 volts. I buzzed out all the connectors between upper and lower boards and everything is sane.

Unsure what I should chase. Thanks for any suggestions.

Here are a couple pictures captured showing the glitches. The seem to be in the top half of the screen. They're similar in each slot.

mmm, it will not be an easy task. Do you have any hi res pics of the inside of your slot (just to check first what chips are inside)

pnauts said:

mmm, it will not be an easy task. Do you have any hi res pics of the inside of your slot (just to check first what chips are inside)

Click to expand...

Confused, inside which slots? Do you mean of the top board?

i am pretty sure he means clear pictures of the boards showing the Chips and caps. Top and bottom if you can. you might have a bad trace or bad solder joints etc

Some happy news. Increasing voltage to 5.41 makes the dots go away. But what's casing the power draw?

harness length, solder quality and current consumption of your set, for example un MV2 is around 1A on the 5V
the measure you done is close to the slot or measured to the PS ?

pnauts said:

harness length, solder quality and current consumption of your set, for example un MV2 is around 1A on the 5V
the measure you done is close to the slot or measured to the PS ?

Click to expand...

Yeah measured at the game board 56 pin and JP1.
It working is great but the 12v is pretty high, too. The datasheet says the HA13001 can run up to 18v. Currently am using two switchers on my test rig (one for the 5.4v and other as 12v) as I try to find ways to improve the power issue. I'm going to test it in the cab today and see how it behaves. Assuming it won't run properly or boot, though.