https://www.pictorial64.com/

The Pictorial C64 Fault Guide

The definitive pictorial diagnostic guide for Commodore 64 computers.


This guide lists pictures of various Commodore 64 problem scenarios
along with their descriptions and known causes. Use it as a tool to
assist in diagnosing C64 issues, to get a general idea of what might
be wrong with your machine. Keep in mind that it's rare to find an
exact match and sometimes multiple different problems can cause a
similar faulty screen. This site focuses on the classic breadbin
models, though many of the fault scenarios are also applicable to
newer revisions such as the C64C. For the best results, use this
guide in conjunction with the other C64-related sites listed here.


Even if the guide can't pinpoint the exact failing component for you,
it may be able to point you toward the general area of the fault on
the mainboard. Getting a RAM-like symptom but all memory chips tested
working? Maybe there is a broken trace or solder joint near the RAM
chips.


Since audio problems are difficult to portray with pictures, here is
a separate section for them.


The site will always be a work in progress, more pictures will be
added as they become available. If you have a picture to contribute
or questions about the currently listed problems/causes, feel free to
contact me:


derbiangames@gmail.com


Best of luck in bringing these legendary old computers back to life!


Click on an image for fault details.

Dark mode

[ ]

Normal Startup

#

Non-faults

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#
#
#
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#
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U1 (CIA)

Common failure!

General tips

[u1_1]
[u1_2]
[u1_2b]
[u1_2c]
[u1_3]
[u1_3b]

U2 (CIA)

Common failure!

General tips

[u2_1]
[u2_1b]
[u2_2]
[u2_3]
[u2_4]
[u2_5]
[u2_5b]
[u2_6]
[u2_7]
[u2_8]

U3 (Basic ROM)

General tips

[u3_1]

U4 (Kernal ROM)

General tips

[u4_1]

U5 (Character ROM)

General tips

[u5_1]
[u5_2]
[u5_3]
[u5_4]
[u5_5]
[u5_6]
[u5_7]
[u5_8]
[u5_8b]
[u5_8c]
[u5_9]
[u5_10]

U6 (Color RAM)

[u6_1]
[u6_2]
[u6_2b]
[u6_3]
[u6_4]

U7 (MPU)

General tips

[u7_1]
[u7_1b]
[u7_2]
[u7_2b]
[u7_3]
[u7_4]
[u7_5]
[u7_6]
[u7_7]

U8 (Logic)

General tips

[u8_1]
[u8_2]

U9 - U12, U21 - U24 (RAM)

Common failure!

General tips

[u9_1]
[u10_1]
[u11_1]
[u12_1]
[u12_2]
[u21_1]
[u12_3]
[u9_2]
[u9_2b]
[u12_4]
[u24_1]
[u10_2]
[u21_2]
[u21_2b]

U13 (Logic)

General tips

[u13_1]
[u13_1b]
[u13_2]
[u13_3]
[u13_4]

U14 (Logic)

General tips

[u14_1]
[u14_2]
[u14_3]
[u14_4]
[u14_5]
[u14_6]
[u14_7]
[u14_8]

U16 (CMOS quad bilateral switch)

[u16_1]
[u16_1b]
[u16_2]

U17 (PLA)

Common failure!

General tips

[u17_1]
[u17_2]
[u17_3]
[u17_4]
[u17_5]
[u17_6]
[u17_7]
[u17_7b]
[u17_7c]
[u17_8]
[u17_9]
[u17_10]
[u17_11]
[u17_12]
[u17_13]
[u17_13b]
[u17_14]
[u17_14b]
[u17_15]

U18 (SID)

See also: diagnosing audio problems

[u18_1]
[u18_2]

U19 (VIC)

General tips

[u19_1]
[u19_2]
[u19_3]
[u19_3b]
[u19_4]
[u19_5]
[u19_6]
[u19_7]
[u19_8]
[u19_9]
[u19_10]
[u19_11]
[u19_12]
[u19_13]
[u19_14]
[u19_15]
[u19_16]
[u19_17]
[u19_18]
[u19_19]
[u19_20]
[u19_21]
[u19_22b]
[u19_22]
[u19_23]
[u19_24]
[u19_25]

U25 (Logic)

General tips

[u25_1]
[u25_2]
[u25_3]

U26 (Logic)

General tips

[u26_1]
[u26_2]
[u26_2b]
[u26_3]
[u26_3b]
[u26_4]
[u26_4b]
[u26_5]
[u26_6]
[u26_7]

U27 (Logic)

General tips

[u27_1]

U31 (Oscillator)

General tips

[u31_1]
[u31_2]
[u31_3a]
[u31_3b]
[u31_4]
[u31_5]
[u31_6]

CT1 (Trimmer Capacitor)

[ct1_1]

F1 (Fuse)

[f1_1]

Capacitor

[c_1]
[c_2]

Trace

[t_1]
[t_2]
[t_3]

Power supply

General tips

[psu_1]
[psu_1b]
[psu_1c]
[psu_1d]


Additional diagnostic and repair guides:

  * Step-by-step Commodore 64 repair guide
  * Ray Carlsen's CBM repair guides
  * Ray's pict-o-guide (more fault pics here)


Communities where you can ask for help with your C64 issues:

  * Lemon64 forums
  * Comp.sys.cbm
  * C128.com forums
  * Forum64.de (German)


Informative C64 repair videos:

  * Jan Beta
  * Adrian's Digital Basement
  * GadgetUK164
  * KOJRO Retro Innovations


If you found this site useful, you can show your support here.
Every donation is very much appreciated, and helps keep the site
up-to-date and running.




(c) Derbian Games, 2023

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