cchocjr Posted June 10, 2006 Report Share Posted June 10, 2006 First off, please accept my apologies for the ponderous ignorance I am about to display and the effort which you will surely need to restrain yourselves from hitting me :).I'm getting started with my single-sid midibox--which I'm super stoked with--and I'm having trouble navigating the two diagrams provided on this site for re-using bits from the c64, in particular, the power supply. I've attempted to search for the solution(s) before reaching out, but I've not really had much luck.After my first attempt at following the non-optimized reused c64 PSU, I got the voltages I needed on the core unit, but was not getting what I needed at the Sid module. I know that the c64 PSU delivers two voltages, and these are labled in the .pdf (what the hell is that third AC connection?), and I know that there are different revision PSUs. At first, I just followed the diagram and, like I said, I got 5v where I should. I then rewired my rinky-dink little power board (using two switches, because I haven't the faintest clue about how to re-use the original c64 power switch), using voltage readings rather than the diagram as the basis for my wiring. Now I'm getting around 7v over the connections, and I am no longer getting 5v where I need it on the core unit. Can anyone point me in the direction of some simplified steps on how to tackle the power supply issue or offer any guidelines. I would really love to get my hands on a step-by-step guide on achieving the proper power distribution, as I've only just started tinkering with electronics and am not too hot with diagrams, etc.Any help you can offer would be insanely appreciated.Thanks,Charles Quote Link to comment Share on other sites More sharing options...
stryd_one Posted June 10, 2006 Report Share Posted June 10, 2006 heheheh Hi Charles!After my first attempt at following the non-optimized reused c64 PSU, I got the voltages I needed on the core unit, but was not getting what I needed at the Sid module. That makes me think your PSU might be no good. If you connect everything up exactly as the PDF says, you should be right to go... I got 5v where I should. I then rewired my rinky-dink little power board (using two switches, because I haven't the faintest clue about how to re-use the original c64 power switch), using voltage readings rather than the diagram as the basis for my wiring. Seeing as this is kinda new to you, I think it's best if you just do what the PDF says.... It should work, and if it doesn't, either you did something wrong or something is broken :( Just follow the diagrams and test the voltages afterwards... Quote Link to comment Share on other sites More sharing options...
Wilba Posted June 10, 2006 Report Share Posted June 10, 2006 One problem you might be having is that the non-optimized version is less parts but a bit hard to follow and hard to measure.Go with the optimized version. It might mean desoldering your 5v regulator from your Core PCB, but that's not too bad.The key to the "optimized" design is the 9v AC supply is rectified and regulated into 9v DC and then added to the 5v DC supply coming out of the C64 PSU to make 14v DC. You can see it being added by the GROUND of the 9v regulator connected to the +5v line (between power switch and 2200uF capacitor). From memory, the middle two pins of the switch are either connected to the "front" two pins or the "back" two pins, like two parallel, independant switches. So just test it with a multimeter first to make sure you got it the right way round.1. Test outputs of C64 PSU... test the 9v AC and 5v DC are coming out of it.2. Wire it up as per the diagram.3. The voltage at pin 3 of the 9v regulator should be 9v above pin 2. Remember, the ground of the 9v regulator is not a real ground. The regulator just regulates the output to be 9v above pin 2, which happens to be 5v above the "real" ground, so the result is 14v above the "real" ground, which is the ground of the 5v DC (middle pin of the C64 PSU).Hope this helps.... Quote Link to comment Share on other sites More sharing options...
cchocjr Posted June 10, 2006 Author Report Share Posted June 10, 2006 Well, it looks like my power supply is faulty. I'm only getting a little more than 5v on the AC pin. Guess I'll have time to stare at the optimized solution diagram while I search out another PSU.Thanks for your replies, everyone. I'm sure you'll hear from me again.Charles Quote Link to comment Share on other sites More sharing options...
Wilba Posted June 11, 2006 Report Share Posted June 11, 2006 Sorry if I'm treating you like a complete newbie here, but are you sure you used the "AC" mode on your multimeter when you tested the AC pins? You said you previously had good voltage on the Core using the original circuit... so maybe the PSU isn't faulty. Quote Link to comment Share on other sites More sharing options...
madox Posted June 11, 2006 Report Share Posted June 11, 2006 Sorry if I'm treating you like a complete newbie here, but are you sure you used the "AC" mode on your multimeter when you tested the AC pins? You said you previously had good voltage on the Core using the original circuit... so maybe the PSU isn't faulty.Normally reading AC signals with a DC mode meter will give around 0V. At least my multimeter behaves this way. Quote Link to comment Share on other sites More sharing options...
cchocjr Posted June 11, 2006 Author Report Share Posted June 11, 2006 I did use AC mode on the multimeter, yes. had ground lead to ground pin and hot lead on AC pin. I tested all pins just to make sure that there wasn't something funky going on, and the AC pin was the only one with a substantial reading.Feel free to treat me like a newbie, because [drum roll] I am a newbie. I am certainly not beyond making a dumb mistake (or numerous ones.)Thanks,Charles Quote Link to comment Share on other sites More sharing options...
Wilba Posted June 11, 2006 Report Share Posted June 11, 2006 You should be measuring the AC voltage between the two pins on either side of the "notch", i.e. between pins 1 and 7. Just checking, as you said you had the ground lead to the ground pin, which is a bit ambiguous, and one could think you meant the ground pin at pin 4 (the ground of the 5v DC supply). Quote Link to comment Share on other sites More sharing options...
cchocjr Posted June 12, 2006 Author Report Share Posted June 12, 2006 Ahhh. No, thanks for pointing that out. In light of your words, I would say that I was not measuring the AC current properly. I'm out of town on business for the week, but I will double check my work when I get back to Atlanta.Thanks again for your responses everyone. You folks are as helpful as the folks on the x0xb0x forum, which is a compliment.Thanks again,Charles Quote Link to comment Share on other sites More sharing options...
Wilba Posted June 12, 2006 Report Share Posted June 12, 2006 Glad to be of help :)Just take it in stages and you'll be right. Build the top half bit, that turns 9v AC into 9v DC, the rectifier X1, the 7809 and the two capacitors in between, then test this outputs 9v DC (between pin 2 and 3 of the 7809). Quote Link to comment Share on other sites More sharing options...
madox Posted June 12, 2006 Report Share Posted June 12, 2006 Ahhh. No, thanks for pointing that out. In light of your words, I would say that I was not measuring the AC current properly....I don't mean to be a pedant, but you are talking about AC voltage, right? Not current?Just on a side note, do you understand about voltage references? It's a topic which is a bit too often overlooked, even by some engineers and technicians I've worked with. I think it's worth reading about the fundamentals a bit, as it really helps to understand the different kinds of signals, like AC, differential, positive/negative/0V ground rail referenced signals.I guess you've been warned before, but make sure you take care with any mains voltage supplied equipment. Even experienced professionals make mistakes sometimes. It's too easy to do. There are too many horror stories. Just take it slowly, and think about every step before you do it. Quote Link to comment Share on other sites More sharing options...
cchocjr Posted June 13, 2006 Author Report Share Posted June 13, 2006 You can be the King of Spain, for all I care, so long as you offer sound advice / strategem! ;D Quote Link to comment Share on other sites More sharing options...
cchocjr Posted June 17, 2006 Author Report Share Posted June 17, 2006 Alright. To the best of my efforts, I'm not getting 9 VAC, just 5 VAC. Looks like I'll be procuring another c64 power supply (when I get paid).Thanks for you help, all.Charles Quote Link to comment Share on other sites More sharing options...
aminoplacid Posted July 16, 2006 Report Share Posted July 16, 2006 Thank you for this. Confusion subsiding. I have been testing the DC out voltages from the rectifier and I am getting 5 volts. Any ideas as to why this might be? I have checked my wirings hundreds of times already and it's seems good. Anythings helps (BTW also a super-noob)Derek Quote Link to comment Share on other sites More sharing options...
Mr modnaR Posted July 16, 2006 Report Share Posted July 16, 2006 I have been testing the DC out voltages from the rectifier and I am getting 5 volts.that is correct. the c64 PSU outputs 5VDC and 9VAC Quote Link to comment Share on other sites More sharing options...
EvilEvilEvil Posted November 5, 2006 Report Share Posted November 5, 2006 I'm not getting ANY volatge out of my AC pins! NOOB HERE TOO.I set my multimeter to ~50V, nothing. 5v DC works fine though. I am testing them by putting the multimeter pins against the AC pins. Any suggestions? Quote Link to comment Share on other sites More sharing options...
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