Amiga

by Dario on Amiga, Repair

AMIGA 500 Rev5 Green Screen Repair

Got this Amiga 500 Revision 5 computer in a non working state. Initial problem was a black screen. Upon reseating the AGNUS chip, the machine showed a green screen. Green screen usually means bad RAM, first thing I tried was to burn an EPROM with DIAGROM and fit it in the ROM socket with an adapter for revision 5 motherboards. DIAGROM was unable to show me something on screen via the RGB video output, so I connected another computer to the AMIGA with a serial cable. With this method the output of DIAGROM was that the chip RAM was bad, the problem is that we still need to identify which ones are the bad ones, there are 16 RAM chips soldered to the pcb. Read More >>

 
by Dario on Amiga, Repair

Commodore 1702 Monitor, missing color

1702 Monitor had picture but no color.

First thing to check was that the Commodore 64 computer itself wasn’t the culprit, so I swapped it for another video source and the problem continued. I’ve noticed that touching the switch in the back that selects between FRONT and REAR inputs had some effect and the color was present for a brief moment, but then it fade away leaving just a black and white screen. Both REAR and FRONT inputs had the same issue. Read More >>

 
by Dario on Amiga, Repair

Amiga 1200 faulty CIA fix

Got this A1200 that was working fine except for some random crashes. Upon performing the Amiga Test Kit, it showed a fault in a CIA timer. The 1200 has smd components, that means you need a hot air station to remove some chips. The following pictures shows the removing process of U7. Then I added a PLCC socket for the new CIA ic. Machine fixed. Read More >>