Many of you may think that repairing arcade boards is a difficult task but sometimes it’s not so (well, few times though…).Here is an example.

Got an IREM Major Title PCB (M82 hardware) from my friend Corrado (who is part of JAMMArcade team as contributor):

When I powered it up I was greeted from this rolling screen:

There was no SYNC at all.I traced this signal back to a 74LS32 @IC14 on video board but, after checked its logic, it seemed good.I noticed there were some socketed ICs both on CPU and video board.Two of them were TBP24S10 PROMs manifactured byTexas Instruments (you can read its specifications in our “datasheet” section).When I pulled of the socket the one @IC47 I got this:

PIN16 (VCC) was broken so IC was not powered at all.A little bit of “reconstructive surgery” on this (other adiacent wobbly ones) pin was enough to restore the correct video syncronism (later I found that outputs of this PROM were connected to a couple of custom ICs involved in video timing generation).

My friend ‘robotype’ sent me some boards for repair.Among them there was this a “Kid no Hore Hore Daisakusen” PCB (キッドのホレホレ大作戦^? lit. Dig Dig Kid’s Epic Battle), a pretty obscure (for me, at least) game manifactured by Nichibutsu in the 1987 (released in the Western market as “Booby Kids”):

Board uses, surprisingly for its age, JAMMA pinout so I could power it up without the need of building an adapter as I first thought.Here is all I got, some static garbage:

This is clear sign that the CPU is not running so for first  I probed the 68000 main processor.Starting my checking from pin 1 all was stuck LOW or HIGH until I came to CLOCK (PIN15), this was completely silent.I traced it back to a typical clock circuit made of an inverter 74LS04 and a 74LS74 as divider.These ICs were good but when I went further back till to the 16MHz quartz I got this on my scope:

It was completely dead!Replacing it brought PCB to life again.