Oct. 5, 2006
This is a neat little pinball. Found in dead condition. High wear on playfield. Cabinet and backglass very good. Here's a photo of the machine with the head removed.
The main CPU pcb was corroded by battery leakage. The corrosion ran up the board to the typical places.
After a nice long bath in vinegar and water to neutralize the acid I removed the ICs and replaced sockets as necessary.
Oops - the legs fell off the ROM at U6 - nasty stuff. Now, being the frugal pinball mechanic that I am, I was able to clean the other legs and solder some kynar wire to the remaining stubbs of 4 legs. I stacked this onto another socket and plugged the whole thing into the board. It is necessary to test all connections from beneath pcb to legs on rom to make sure the electrical connection is secure. Yeah, I know, a complete rom set is only $10 - BUT - if you don't need one you don't need one. Maybe I'll buy a rom burner some day. And besides the machine isn't going on location or being sold.
Ok, now the fun starts. You've gotta ask yourself - did I repair 6 broken traces or 5? Plug the PCB into a computer power supply and count the LED blinks. Well, I saw no blinks. I hooked the pcb up to a FLUKE 9010A w/ 6800 pod.
The Fluke 9010A easily identified a couple of bad data line on the ram at address 0000-007F and a problem with the cmos ram at 0080. The cmos ram can be tricky as it's only 4 bits and will appear to fail using the Fluke even when it's working. Keep in mind only the upper nibble (4 bits) of data will function. The lower 4 bits will always read 'F'.
The rom locations showed data and each data line toggled. Since I have no rom burner I had to hope the roms were good. Well, that did the trick - after fixing the ram data lines AND replacing some components around the LED and testing as much conductivity between components as I could I fired the board up and got 6 blinks - one quick and 5 short. The missing final blink implies the 43V solenoid line is down SO I put the board in the machine and crossed my fingers.
Viola - the machine blinked and booted and said "PAC-MAN"... Cool!
Now on to other matters....
I ran the maintenance tests and mostly the game worked except for the playfield solenoids were dead. The 1 asb fuse was blown. This implies a shorted driver transistor and/or coil or coil diode. Replacing the fuse allowed the upper drop target reset coil to release smoke and clue me in. The coil was shorted and so was the drive transistor. I will re-wrap the coil later so for now I've just disconnected it to see what other issues exist. To my surprise no more major issues. A few lamp drivers are out and a playfield tuneup is required but the major issues are out of the way.
Oct 17, 2006
Here's some black enamel playfield restoration. It looks ok - not great.
Here's some of the raised wood - looks really bad here. I had to sand this down to smooth it but did not attempt to paint it. One of the problems with using paint is that when you clean the playfield the paints comes off. Pinball playfields originally used inks, not paint. Degreasers tend to act as paint removers.
Here's the before and after effects of using 'Magic Eraser' to remove ball swirls and embedded dirt. This works great.
Here's a shot of the completed game.