Friday 31 October 2014

Missile Command PCB fix

Board location E5 - 74160 dead output at pin 12 and other outputs suspect.

Confirmed as faulty in IC tester.
Fixed! :)

Saturday 25 October 2014

Arcade Garage 1.0

Well after close to four years, all the cabs I own are (touch wood!) working, Well I need a new starter for my Tempest Fluorescent light, but thought I best capture them while they all do work. My current line up consists of:

Fire Truck, Jet Fighter, Electrocoin Midi with a dual JAMMA adapter playing Pac-Land & Wonder Boy, Tempest Cabaret, Centipede Cabaret, Hang-On and Pole Position.

On the way to getting my current lineup I’ve also owned the following cabs: Lethal Enforcers, Cruis’n World, Missile Command Cabaret, Asteroids Cabaret, a Popeye Pachislo & 2 JAMMA cabs.

Photos below and a video, sorry for the lack of commentary but I’ve got a stinking cold at the mo and the vocals don’t sound too good.

ATARI Hot Wheels!

Monday 13 October 2014

Tempest. Board repair.

This board failed on me back in March, and I briefly looked at it but didn't really have the enthusiasm to fix it at the time, fast forward six months and here we go again...

So upon re-testing the boards, the X axis output had stopped working, this was caused by a failed TL082 at location D/E12 on the main AVG board, pin 7 wasn't outputting anything, I fitted a new socket and replacement IC and had a stable output again, back to where I was six months ago.

Last week I got stuck into this fault again, (Crazy vectors and Showing Mathbox error in test mode) I have spent a good few hours probing with a scope and logic probe to try and track down where the issue was, I got the schematics printed onto A1 paper at work, I even de-soldered all the proms from another Tempest AUX board to double check my proms had verified correctly, which they had.

Now, convinced that it wasn't a Prom/Bitslice/Socket or Interlink cable, I honed in on the remaining IC's in the Mathbox area. E4 a 7408 (quad 2-Input AND gate) got my attention, now I'm not really proficient enough in fixing boards to understand what was wrong but pin 6 which drives the clock input of B1 (374) didn't look pulse correctly on my logic probe, the frequency of the pulsing was all over the place and the HI/LOW LED's were going 'mental' in an odd way. I tried piggybacking a known good chip onto the 7408 to no avail, not deterred I de-soldered it and put a socket on the board. I then tested the IC in my Programmer which also tests 74 series logic, and sure enough one of the gates reported faulty. I put a new 7408 in and BOOM! The game is working again!

I have ordered new TL082's, MC1495's, trim pots for X/Y size/position adjustments and will fit these when the arrive to hopefully improve the reliability of this board, but for now I think I'm due a few credits. :)