Troubleshooting

COMMODORE VIC20 COMPUTER - DIAGNOSTICS AND REPAIR [1]

LATEST VERSION CR BOARD: ASSY #250403 FAB #251040-01 REV D 1981/2

UAB3 6522 VIA INTERFACE, SERIAL-JOY-USER-CASS

Black screen [2]

UB4 7406 LOGIC SERIAL PORT BUFFERS

Black screen [3]

UD1 CD4066 QUAD SWITCH (LOGIC GATES)

Character colours wrong

Character colours wrong

http://sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?f=11&t=7957&p=86671#p86671

UD7 901460-03 ROM CHARACTER

The characters are not displayed correctly indicates a ROM failure

Broken CHAR ROM

[4]

UB7 6560-101 VIC VIDEO/AUDIO

Yellow screen, high pitched tone. Reset functions tone changed pitch. Avengers cartridge worked after multiple resets. With small memory expansion, random garble characters appeared on screen after rest. With large memory expansion, display ok. Wrong colours only.

[5]

Loss of multicolour mode

Broken VIC-I

Broken VIC-I

[6]

UE12 901486-06 ROM KERNAL

Black screen

[7]