Wednesday 10 April 2013

Fire Truck fired up.

After getting itchy fingers, I just had to find out if the cab was a worker or not. 20+ years of unknown history would the game fire up or maybe catch fire! I wasn't sure what parts would work and considering the mains cable had been chopped short at the back of the cab it didn't give me much hope..

I unplugged all the connectors gameboard, psu coin mech etc, and verified that they were clean and had no bent pins, I had to straighten a few pins on the interlink loom between the front and back half but nothing major seemed wrong here.

I rewired the mains lead, checked the onboard fuses. The main power switch at the back of the cab had been a casualty over time, at some point it had become good friend with wasps or bees and had become completely destroyed. so I have temporarily used some terminal block to have the cab wired in a permanent 'on' state. The back door interlock mains wiring had also worked free from the connector so this needed re-connecting.

With the gameboard disconnected, I fired the cab up and got the distinctive hum for the mains transformer, no smoke, sparks or pops. Good start! All the Power brick voltages checked out against the schematics which was good.

Time to remove the main game board from the RF cage...It turns out the board is in a very tidy condition, and looks like its never been repaired.

Fire Truck main PCB
A visual inspection didn't show any bent pins on the underside of the board, I gently removed and re-seated all the IC's that were in sockets, and after that put the board back in the cage nearly ready to fire it up.

Before turning the cab on I need to improvise a monitor and the original on in the cab was missing. The video signal from the game was standard composite video so without too much fuss I moved in a little test monitor I have and made some temporary wiring to connect it to the original loom.

Time to turn the cab on, and here's what I got...

Cab fired up for the first time in 20+ years
Wee the cab fired up, I got a good solid video image but something wasn't quite right. I had a loud tone constantly coming out of the speakers, and the the main playfeid graphics were messed up. The game coined up, but the game wont start properly.

The above photo gives a better indication of what is being displayed on screen. Not great but in truth this was a better result than I had expected. I need to confirm all the cab wiring is correct at some point in the future. I tried the test mode switch which is supposed to show some gradient bars and confirm RAM and ROMs are in working order, but this doesn't seem to work. At this point I'm guessing its a game board fault, but due to the unknown state the cab has been in, I will be doing continuity test on the looms when I next get some time to work on the cab.

Thanks for reading, Mart.