2055 EAROM Voltage

mjansma

Active member

Donor 3 years: 2023-2025
Joined
Sep 12, 2023
Messages
208
Reaction score
239
Location
Antioch, Illinois
I'm having an issue getting enough voltage to write high scores to the 2055 on a Centipede board. The best I can get is -26.7

The +/- 22s are measuring 23 and 24, and the +/- 15s are both measuring 15. The -30 test point was only measuring -8.

The 555 was totally dead. I socketed and replaced it and the voltage went up to -26.7

The 1uf cap at C86 tested good, and I replaced the 1N4001 diodes. No change.

In test mode, instead of the usual 4 FF I have a 4 20, and occasionally 4 AA or 4 5B.

Any thoughts?
 

Attachments

  • IMG_7125.jpeg
    IMG_7125.jpeg
    1.1 MB · Views: 2
  • IMG_7111.jpeg
    IMG_7111.jpeg
    860.9 KB · Views: 2
Back
Top Bottom