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2 x Commodore 128 Repair

Clicca per ingrandire l’immagine

I have repaired last year these computers for a dear friend.

Commodore 128 #1

Defect:

  • Black Screen.
  • Missing CAS on PIN 1-4 of the 74LS32 (U9)
  • Missing CHROMA video.

Fix:

  • To fix the problem of lack CAS on 74LS32 i had to make a bridge from the PIN 41 of the PLA 8721 because a pcb track under the socket was interrupted.
  • Broken solder joints on the RF Modulator.

Commodore 128 #2

Defect:

  • Black Screen but sometimes it works.

Replaced parts:

  • Replaced the socket of the 8721 PLA.
  • Replaced 8721 PLA (U11).

Note:

The main problem was the PLA. In the C128 mode sometimes works and sometimes not. Works always C64 mode.

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