DigDug (Atari/Namco) PCB repairs
Problem: Scrambled Video, Game won't boot
First order with all older Atari cabs in this state,
check the power supply. The Big Blue 27,000uf 15V cap goes bad and
screws up the power. I was getting about 16 VDC on the 10.6VDC lines.
Looks like it might be Big Blue. Swapped it out and fired it up and
I had a Working DigDug. But there was no sound. See the next entry for
the sound problem.
Solution: Installed a new Big Blue 27,000uf 15V cap in the power supply.
Tools: schematics, soldering iron, solder wick
Problem: Sound was very faint
I first tried switching in a known good power supply, this changed
nothing. So I swapped out the Regulator/Audio II board from my Centipede.
Same results. After verifying the power supply worked in my Centipede, I knew I
had a board problem. All the wires and the sound pot were good. First thought
was to change out the audio amplifier on the PCB. I removed the old one, installed
a socket and put in a new LM 324 chip. Powered it up and Bingo! Fixed the problem.
Solution: Installed a new LM324 audio amp at location 3D/E.
Problem: dead board
I first tried reseating all the chips, no go. Next, I noticed a bent
pin on one of the three Z80s. Since I had a tube of Z80s, I swapped all 3 of the CPUs.
And the board ran. Later I tested each Z80, they were all dead.
Solution: Reseat all socketed chips and replace 3 Z80 CPUs.
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