C64

• http://www.linusakesson.net/scene/lunatico/misc.php
• http://www.linusakesson.net/programming/poems-for-bugs/index.php
• http://www.aaronbell.com/secret-colours-of-the-commodore-64/
• https://www.metafilter.com/114704/Demoscene-The-Art-of-the-Algorithms
• https://digitalerr0r.net/2011/04/30/commodore-64-programming-6-raster-interrupts/
• https://csdb.dk/forums/?roomid=11

• Supermon Overview

• Black PSU - 5.1v/10.3v - 5.13v/10.40v
• White PSU - 5.15v/10.2v - 5.19v10.43v

• Arduino Kernel Rom
• JiffyDos DolphinDos Mod
• JaffyDos

• Remove ICs
• Heatsinks
• #11 "Zero Insertion Farce?" — Installing ZIF Sockets on a C64 Motherboard
• Sells Nordic Replays, C64 Reloaded Motherboards, SuperPLA
• EEPROMs as ROMs
• Using the USB Logic Analyzer with sigrok PulseView
• C64 Video Cables
• https://github.com/fdivitto/FabGL

Dead Drive

• https://www.lemon64.com/forum/viewtopic.php?t=64021
• https://www.youtube.com/watch?v=CDj6JEqPkzA
• C15 Capacitor

Dead C64

• Black Screen Guide
• Another Black Screen Guide
• https://www.youtube.com/watch?v=Mn1keRFXX7I
• Test Fuse
• Test for 5 volts on chips
• check +12V on pin 13 of the VIC
• 5 volts on userport
• https://github.com/jamarju/c64_test_tools
• Commodore 64: how to repair it, step by step

• Replacement PLA, local (more expensive), Alternative, cheaper from the store
• Replacement Capacitors
• #01 "A Change of Heart" — Commodore 64 Black Screen Repair
• aphexteknol
• the 250425 board should in fact boot to the familiar blue BASIC screen just fine without U1 and/or U2. (However, with U1 gone, e.g. the keyboard obviously won't work and with U2 gone, e.g. the serial port won't work).

• Chip Data
• Datasheets

VIC-II

• [1] - £23.84 (AUD$45.19)
• Commodore 64 VIC-II MOS 8565 R2 PAL video chip 5v (*TESTED*)! WRONG CHIP. Also dodgy and more expensive...

RF Mod

• I did this RF mod mod
• Removing the RF modulator on a C64 (PAL, 1983, W. Germany 251137, Rev B)

TODO

• Black Screen. Pulses monitor/pops when turned on.
• Power supply seems ok (5.18v). Fuse replaced (I managed to blow it while poking around with the multimeter :/)
• Nothing shows up when toggling on and of rapidly (PLA check).
• Disk drive spins up when turning on.
• Load "$",8 does nothing (not sure the disk drive is working, had to replace a capacitor). Tried poke commands to make sound without success.
• Check VIC-II Vcc is 5v. pin 40 is 5v
• you're looking for the RESET line to be grounded for half a second during powerup. Pin 3 of userport. RST line goes high after half a sec (and stays high)
• No ram chips over heat. Only hotish chip is 6510
• Clock in on 6510 (pin 1) *seems* to be toggling (unsure, multimeter measures it lower than 5v but not ground).
• Clock out from 6510 seems to be stuck at 5v
• Address lines 0-11, seem to be under 5v but not GND. Except for pin 12, 13, 14, 15 which are 5v.
• Can I use Chroma/Luma on a composite monitor (ie for just black & white image)?

PLA

• http://forum.6502.org/viewtopic.php?f=8&t=3465

Dead Monitor(s)

• https://www.lemon64.com/forum/viewtopic.php?t=28565&amp%3Bstart=30
• https://gona.mactar.hu/Commodore/monitor/Commodore_monitors_by_model_number.html
• "found that CP2 has disintegrated! It`s a paper capacitor next to the power switch that has exploded, so that needs replacing.", "the x2 cap is a common failure"

Power Switch

• https://www.youtube.com/watch?v=g2lrrXp-Zn8
• http://www.retro-commodore.eu/2014/04/12/c1084-power-switch-replacement/
• https://randommayhemstuff.blogspot.com/2016/11/finally-swapped-power-switch-on.html 1084
• https://www.wagneronline.com.au/pcb-mount/switches/electronic-components/swp583-2978/347/pd/ PCB MOUNT PUSH SWITCH $11.50
• http://www.telespares.com.au/index.php?main_page=product_info&products_id=312936 (Much cheaper, not sure if the same)
• https://www.thefuturewas8bit.com/1084switch.html (OUT OF STOCK)
• https://au.element14.com/c-k-components/ne18-2a-ee-sn-p-6amp/switch-pushbutton/dp/2435346 - Maybe this is the same
• https://www.lemon64.com/forum/viewtopic.php?p=667259&sid=d8a1ae892e1436641358a9501da82ad1

Games

https://www.youtube.com/channel/UCnhr67lnXf3ZtcKLrr9-hSA/videos

Repair

I'm trying to repair my C64. It is a PAL, ASY 250425

It black screens.

• I have tried a deadtest cart but it still blackscreens.
• Screen does 'pop' when turned on and it's a different level of 'black'. No borders. No sparkles. Just black.
• The power supply is under 5.2v.
• The voltage regulators on the board are outputting the right voltages.
• Removed the SID
• Removed one of the CIA's (the other is socketed)
• I have replaced the PLA with a PLAnkton.
• Replaced the VIC-II with a new one.
• Replaced the clock generator with a TOLB (I'm fairly sure I broke the original while poking the crystal with a multimeter :/).
• The reset line stays low then goes high after a few secs.
• I am getting 984.9 Khz clock in and out on the 6010.
• There is activity on the CPU's datapins.
• _IRQ stays low.

I have tried using poke commands to generate sound without success. Also tried to make the disk drive do something via load with no response (but I'm not %100 sure the drive is working). Is there something I can do with the tape drive? (When I press Play it spins continiously).

None of the chips feel particularly hot (The VIC-II's get a bit hot but afaik that's normal).

I don't have another C64 to swap things with. I have a multimeter with freq meter. A 8ch logic probe. (No Oscilloscope).

My current next possibilities is to either:

• Remove the M1 RF Modulator and replace it with a hand built one.
• Remove the other CIA and the ROM chips and try the deadtest cart again (Since it doesn't need them).
• Remove all the ram chips and test them with an Arduino.

TODO

• German stuff
• Manual tape control via pokes
• "if the 60Hz can be found on _IRQ (pin 3), the KERNAL was able to program the CIA timer". "IRQ has a duty cycle of 98% high (2% low)", "IRQ -> generated by the CIA, but no IRQ does not automatically mean CIA bad, with no IRQ the sytem should start w/o cursor (blink)"
• Check the chip select lines on the PLA.
• "verify AEC (pin 5 of the CPU) in relation to PHI0. If you don't catch a badline it looks like AEC is the same as PHI0, only slightly shifted. With a badline, AEC would be LOW all the time."
• "The _CAS signal on the VIC"
• Investigate that 'himem' bodge wire...
• Diagnostic guide RAM Check...
• Replace CIA and try typing poke commands again...
• Remove more chips...

http://retro64.altervista.org/blog/commodore-64-repair-a-quick-guide-on-the-steps-required-to-fix-it/

• pin 21 (color clock, 17.73 MHz) and pin 22 (dot clock, 7.88MHz).
• Test Points
• _CS on the ROMs: The BASIC-ROM (901226-01) is not addressed in idle mode, but access can be produced simply by pressing the RETURN key
• The duty cycle of _CAS must be higher than that of _RAS for the DRAM to work.

 Signal where?  Frequency duty cycle 
 PHI0 CPU Pin 1 985 KHz 50% 
 _IRQ CPU Pin 3 60 Hz 98% 
 _RAS VIC Pin 18 1.97 MHz 27% 
 _CAS VIC Pin 19 1.97 MHz 41% 
 Dot Clock VIC Pin 22 7.88 MHz 56% 
 Color Clock VIC Pin 21 17.73 MHz 45%

• "If you plug in a cassette tape does the motor run if you press play? If it does the computer's running, it's just something screwing up video (I had a faulty RF modulator do that to me once)"