I had a problem with my C64 power supply last night. For some reason my newly bought cheap ass multimeter doesn’t test for AC voltage as low as 9V (is fine for around 200V!). 5V was working fine. I tested the DC voltage across the rectifier on my PSU board and got nothing. I rigged up a light bulb to the 9VAC pins and nothing. I got as far as searching ebay and opening a “wanted UK C64 PSU” thread and thought I’d take the old one to pieces to see what was in there and was presented with two internal fuses… One was burnt out… Problem solved, fuse replaced and all voltgas correct (ish)…
I’m getting just under on the 12V rail and I think my 5V is also something like 5.15. I’m taking a risk that it shouldn’t too much difference… I’d appreciate it if someone can let me know if it’s too much of a risk. This is after the regulator anyway so i’m guessing my multimeter is badly callibrated.
One point angel… The schematic is your friend. Even if you don’t have too much electronics experience, you should be able to work out what’s going on and where the power is going, just break it down in to sections and see how it correlates to your PCB. If you try these things and you manage to sort a problem out then you will be dead chuffed and will have also progressed along the learning path and equally as important you can help somebody else out if they encounter the same problems!
i might be having the same problem you were having goblinz, my little radioshack 20$ multimeter will not rate below 200v in ac, but on the 200v i get 1.2 could this mean 12volts?
i cant wait till i get the power done, i now have all the sid modules done, but only 1 of each i need 2 more douts and 1 more din, and i think for now i will just do a 1 sid in stereo, so one more sid module.
not to get side tracked on posted before,but i was also thinking that if the last topic on finding what ever part was done 2 years ago, that people may now know of a cheaper site or a site with more colors or sizes of that part than was known 2 years ago when the topic was 1st wrote.
Overvoltage on 5v rail COULD mean that the regulator chip is starting to fail. 5.15v today, 12v tomorrow! But from what I’ve seen, it’s common that people measure more than the nominal 5.00v… Does a bit of load even it out? Info on the subject: http://personalpages.tds.net/~rcarlsen/cbm/pstester.txt
How about sticking it into a wall power socket and finding out?
With all due respect, I don’t think htat angel has demonstrated the kind of skill level that would make this safe. Angel, please don’t try to mess with mains level voltage yet. You may have greatly annoyed me, but I don’t want to see you dead.
And yeh, 5.15v is hardly overvoltage. Your cheap multimeter can be blamed for these small inaccuracies.
I’d never test mains voltage with one of those hobbyist multimeters.
I would only trust an electricians multimeter,
which have much thicker probes and much higher voltage rating.
I remember my first time testing the 12v AC pins of my psu, and a smell of burn coming from the multimeter.
Mine has 2 Red sockets for the probes, and 1 Black (Com) socket.
I was using the wrong red socket for AC voltages of that size, and hence the smoke coming from the unused socket.
Imagine i had tested the mains voltage with it,
the multimeter would of set on fire non doubt at 20 times the voltage i was testing on the PSU.
Or at least melted it very badly.
I would hope that even a cheap multimeter would have some sort of fuse in it to stop it setting on fire in situations like this. Not that i’m having a go, but if your using a multimeter to test mains electric then I would think that learning how to use it properly would be a bare minimum.
With all due respect, I don’t think htat angel has demonstrated the kind of skill level that would make this safe. Angel, please don’t try to mess with mains level voltage yet. You may have greatly annoyed me, but I don’t want to see you dead.
And yeh, 5.15v is hardly overvoltage. Your cheap multimeter can be blamed for these small inaccuracies.
I would have personally put a *whack in the quote. Mains voltage should be avoided unless you know what yolur doing and there are no other options
Got two older model power supplies, the first one has fuse rated 160mA (T), and there’s 250mA (F) in the second one, I think the c64c models use 250mA fuse, instead of the 200mA. “T” stands for slow-type and “F” for fast type fuse. (There’s also very slow & very fast etc types).
If I remember right, you’re supposed to use slow-type originally in the PSU? They don’t blow up as easily if there’s some over-voltage in the power. Tho, faster one could be safer for the board.
Got two older model power supplies, the first one has fuse rated 160mA (T), and there’s 250mA (F) in the second one, I think the c64c models use 250mA fuse, instead of the 200mA. “T” stands for slow-type and “F” for fast type fuse. (There’s also very slow & very fast etc types).
If I remember right, you’re supposed to use slow-type originally in the PSU? They don’t blow up as easily if there’s some over-voltage in the power. Tho, faster one could be safer for the board.
I think he was talking about the multimeter fuse, good info though enth.
Got two older model power supplies, the first one has fuse rated 160mA (T), and there’s 250mA (F) in the second one, I think the c64c models use 250mA fuse, instead of the 200mA. “T” stands for slow-type and “F” for fast type fuse. (There’s also very slow & very fast etc types).
If I remember right, you’re supposed to use slow-type originally in the PSU? They don’t blow up as easily if there’s some over-voltage in the power. Tho, faster one could be safer for the board.
Edit: What goblins said, i should of being more specific.
I noticed its gone in the older multimeter too which i just use for the continunity beeper,