Viking is a nice Bally from 1980 designed by Jim Patla. This machine
has had mylar on the playfield probably since new, and the playfield
looks very good. CPU board has some acid damage, and doesn't start.
Mikko cleans the playfield
The CPU was OK after cleaning acid damage from board and replacing 5101 CMOS RAM.
Also one transistor in the reset circuit was bad. There is still some problem in
sound board, the sound volume is very low and the sounds are scratchy. First I thought
that the volume pot is bad, but that wasn't the case.
Playfield looks nice, after cleaning and new rubbers.
Some Viking action.
Sound board is now fixed, U8 or LM3900 was bad. Now there's plenty of volume
and sound quality is just fine.
Part of CPU board
The game stopped working. Opening the backbox showed the test LED flashing only five times
at startup. The display interrupt is missing. The previous problems on the CPU board, caused
by leaking battery, had thus also spread even to the display interrupt oscillator U12, but the
problem had been hiding until now. OK, let's change U12. While I was at it, I replaced capacitor
C16 also. And now it works again! I also had to adjust the top eject hole a bit, it was throwing
the ball straight through spinner into outhole unnecessarily often. A slight bend to the hole
kickout arm fixed that.
Viking is now with its new owner.