I like to try to fix things by myself, also to post it and get it fixed I would probably be looking to something between £30 and 50£ (if not more
I'll think about it, thanks for all the tips.
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Help identifying and connecting Commodore 64 Hardware
- Thread starter jumpinjackson
- Start date
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I like to try to fix things by myself, also to post it and get it fixed I would probably be looking to something between £30 and 50£ (if not more
I'll think about it, thanks for all the tips.
well,i instantly offer when people have no idea what they are doing
youtube videos wont help you
have you measured the voltages at the regulators? what does it dont power up mean? its a bit vague
EDIT: plus ,i have no idea why this is in photobooth
youtube videos wont help you
have you measured the voltages at the regulators? what does it dont power up mean? its a bit vague
EDIT: plus ,i have no idea why this is in photobooth
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Granted it was 2am so I wasn't very alert and I'll have to do some more testing. Anyway, it did not seem to do anything at all:
- Power led dead
- No signal to the TV (connected through aerial)
PSU fuse was fine, I'll have a look at the fuse inside the C64, I took this picture when I created the thread, boy there are some components that look pretty battered...
Thanks again Roy.
Thanks to both, but no joy
We will help you. When you say won't power up, what exactly does this mean ? No LED, no picture on screen, black picture on screen ? What cable are you using?
The mainboard is a 250425 ?? Please measure the voltage here:
VR1 (output / right leg)
VR2 (output / right leg)
Solder point (between bottom of U17 and C33)
Do you have any cartridges (Kickman/Jupiter lander) ? Do you have a working C64 as a baseline / test board?
Thanks to both, but no joy
We will help you. When you say won't power up, what exactly does this mean ? No LED, no picture on screen, black picture on screen ? What cable are you using?
The mainboard is a 250425 ?? Please measure the voltage here:
VR1 (output / right leg)
VR2 (output / right leg)
Solder point (between bottom of U17 and C33)
Do you have any cartridges (Kickman/Jupiter lander) ? Do you have a working C64 as a baseline / test board?
Thanks Mate, relly appreciate all the support I'm getting.
- No led powering up
- No picture on screen (connected through aerial)
Don't have diag cartridges or other C64.
I'll start the checks proposed in the previous posts and let you know how it goes.
Thanks again.
No point in checking the voltage regulators at this stage. Follow the power coming into the C64 as follows:
1) Check the voltages at the back of the power input
2) Check the switch voltages, you can desolder it and hotwire as follows:
o o-o|
o o-o|
the right is the board edge and the 'minus' is the hotwire.
3) Check the continuity of the fuse (but this is not the reason for the LED not lighting)
4) Check the bridge rectifier (this can be tricky as you might need to measure at the back of the board - make sure you identify and measure AC and not short out)
5) Check the big electrolyte capacitors for ripple
Ideally you should get a 5 pin DIN -> Composite or 9 pin 262 degree DIN -> S-Video and not mess around with RF.
1) Check the voltages at the back of the power input
2) Check the switch voltages, you can desolder it and hotwire as follows:
o o-o|
o o-o|
the right is the board edge and the 'minus' is the hotwire.
3) Check the continuity of the fuse (but this is not the reason for the LED not lighting)
4) Check the bridge rectifier (this can be tricky as you might need to measure at the back of the board - make sure you identify and measure AC and not short out)
5) Check the big electrolyte capacitors for ripple
Ideally you should get a 5 pin DIN -> Composite or 9 pin 262 degree DIN -> S-Video and not mess around with RF.
1) Voltages at the back of the power input are 10.8V AC between pins 7 and 9, 5.24V DC between pins 4 and 5
2) De-soldered power switch, took it apart, gave it a good clean with isopropanol alcohol, put it back and now the led powers up
Checked with aerial but could not get any picture. I did a composite mod on the C64, as shown in this video: https://www.youtube.com/watch?v=oss-Mcsqurc
Connected the C64 with a composite video cable and I can see that the TV is getting some input because when I switch the C64 on, the TV shows AV as connected and when I turn it off it says NO Signal, however all I can see it's a BLACK SCREEN
. Tomorrow I'll try making a Scart cable to rule out video issues...
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I'll try to get a "new" working unit and check swappable ICs, I also saw some videos on youtube of checks that can be done on ICs with an oscilloscope. Haven't used one since school 30 years ago, maybe I'll give it a go, it'll give me something fun to do.
Thanks for the help.
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Next 2 checks are easy....
Any chips get hot to touch ?
Any MOS77xx or MOS78xx logic chips on board ?
If the u1 u2 and u18 are socketed then remove them. They are not needed just now.
Any chips get hot to touch ?
Any MOS77xx or MOS78xx logic chips on board ?
If the u1 u2 and u18 are socketed then remove them. They are not needed just now.
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Hi mrr19121970, thanks for providing me with further steps to test the issue
My C64 board is a 250425
- U17 PLA and U19 VIC chips get hot, not scorching hot, you can keep your finger on them, but they're definitely hot compared to the other ICs
- No MOS 77xx or 78xx chips on board
U1 and U2 CIA and U18 SID chips removed, still black screen :banghead:
It was the PLA, got a "new" one and hey presto everything works.
Thanks to all for the help.
Thanks to all for the help.
