COMMODORE 64 REPAIRS
About Our Service
Is your Commodore 64 sick, dying or dead? Do you get a dark screen when you turn on your old C64? It's probably not dead, It may just need a bit of attention, a good clean-out and a new chip or two.
If you're thinking this is going to be an expensive fix, then think again. Because we have a wealth of knowledge and a heap of replacement parts we are able to offer a fixed price service, clean and repair. Some of the C64's chips can be quite expensive to buy separately and if you're not sure what you're doing, you can end up doing more damage to the poor old 64 than it's starting with.
The much renowned SID chip could cost you up to £50 to replace alone, and that's just one of many in the machine. Shipping back to you of your working, cleaned^ up and serviced Commodore is included in the fixed price.
We'll also send you a diagnostics report and 30 point check list of the work carried out.
When we repair the machine, where we think necessary we will also change the electrolytic capacitors and heatsink the PLA, CPU, SID and VIC-II as part of the service, at no extra cost!
We use high quality parts such as Genuine Panasonic capacitors & modern replacement SID Chips* (Subject to availability)
In the case where we can't repair your machine, this does happen, we will send you your machine back with a fully refurbished, fully tested working motherboard.
How It Works
Ordering our repair service is easy.
1. Click below to see the buying options.
2. Make your payment using credit or debit card.
3. Check your email inbox for details and instructions on how to package your machine and where to send it. (UK Mainland)
4. Send your machine to us with your name/address and a copy of your receipt, as well as a description of the fault.
5. Sit back and wait about a week and you should receive your working C64 back from our workshop.
Workbench repairing a machine found in a skip.
Close-up work on a C64 motherboard
Workbench repairing a machine found in a skip.
*UK MAINLAND ONLY
The costs for international shipping (in both directions) is very expensive, the shipping costs alone would be more than the actual cost repair, and as such we can only offer this service to UK customers.
Our engineers initial checks before starting any C64 servicing or repairs..
* Physical inspection of case, keyboard (to look for any signs of damage) including burn damage, corrosion, signs of decay etc. external machine/keyboard etc cleaned. Serial number noted for reference. (and revision as revisions vary)
* Machine is opened and inspected as above. Keyboard / power LEDs etc are disconnected as we need to check the system board and power.
* Fuse checked/changed before power on.
* Board and components are cleaned to eliminate any possible errors due to shorts, corrosion etc. Visual checks are completed and resolved if needs be.
* Power supply socket checked / cleaned prior to powering on. If all good, machine is powered on briefly (briefly to see if any issues arise) and stability checked.
* SID chip removed at this stage as some issues can be caused purely by this chip. (not common though). This will be checked later in the process.
* Voltages are checked on DC and AC lines. This includes 9v AC, 5 and 12 V DC for Vic and SID chips.
* Visual inspection again after cleaning to look for corrosion and blown capacitors.
If all good machine is powered on and temperatures taken of IC chips. VIC runs hot as does PLA and CPU, these are given heatsinks if customer willing.
If machine appears stable, voltages taken on RAM chips, and all major IC chips / diodes, resistors checked. (basically most chips have a ~5v input). Important check: VR1 & VR2 voltage checked as these create stable 5 and 12V lines. Large capacitors are also measured here.
Once power circuitry checked we know we have stage one complete which is a machine with the correct voltages flowing through it.
Stage Two. A computer once it has stable power circuitry needs a stable clock pulse. This is done by checking various frequencies on the IC's around the VIC chip. These with the crystal oscillator (17mhz) divide the timings for the CPU and VIC chips. The CPU needs (0.98mhz) clock input to operate and the VIC (7mhz) to create a correct video picture. This is done using an oscilloscope which measures not only the frequency but visually shows any signal noise/signs of instability. Note that different revisions have more or less complexity in the number of ICs (commodore basically reduced the circuitry down to one chip rather than 4 in the earlier machines) so the number of checks here can vary but all create the same output clock frequencies to the machine.
Once we have a machine that is powered correctly and is being given the correct clock signals then we can start actual trouble shooting / servicing. Note that on top of all this, temperatures are monitored throughout the process to look for signs of possible issues further down the line. If any strange odours arise too, the machine is powered off and inspected.
From here a diagnostic cartridge is run (with a minimal chipset) which checks:
1) RAM issues (If this is the case, the process is stopped and must be addressed). Issues here may be the RAM chips themselves or any other number of causes. Normally I like to replace the multiplexers (x2) at this point as they are known to fail and will create RAM problems even if the RAM chips themselves are functioning). This is not definitive however as the PLA can also cause RAM issues.
2) If /when RAM passes, the diagnostics will check that the CPU is functioning correctly (stack page, zero page), followed by the screen memory, the colour RAM (512 bytes), FULL system RAM (the initial boot only transfers the diagnostic to some of the RAM) so can pass initially then fail here after a full check and last the audio chip verified (working but issues can arise here).
3) The CIA's are checked (TOD clock and if they're out of sync, need replacing/troubleshooting). Often I do this later in the process as faulty CIAs can cause other issues. Basically the machine can run the diagnostics without the SID, CIAs, Basic, character and kernal roms plus SID chip), these are then added later in the process and checked/replaced.
Once the process passes, it is left running for around an hour to check stability and again monitored closely looking for anomalies, high temperatures and any signs of possible issues. These are then addressed and checks can be done in the same way with the removed chips aforementioned in place. If all passes as expected then we know we have a functioning base system and from there depending on the job in hand we are now ready to begin any repairs/capacitors changed etc
This is a summary of the first phase which is to check the heart of the system prior to moving on to any other issues. Even with all this working correctly, we are only at the beginning of the journey.