Power Supply problem - SOLVED!!

MIDIbox SID
1

So I built the optimized power supply and plugged it in.

I had the led connected and it glowed for a second and then went out. I measured power on the board and there’s none. I also measured at the plug end (the part that plugs into the optimized power supply from he commodore PSU) and there’s nothing there either. So it looks like my commodore PSU is kaput. Is this a regular occurrence? Is it fixable? Or should I go ahead and buy another PSU. I see there are replacement ones on eBay. Would anyone recommend them?

Thanks in advance, and I hope someone can help!

Karl.

2

Hi Karl,

unfortunately, damaged C64 power bricks are quite common - sometimes, failing voltage regulators even pump excessive voltage through the system, which has not happened to you, as you measured no voltage :sweat:

There are many alternatives around - from pure switchers (ask moonk), to hybrid switcher-linear solutions (ask orange_hand) to linear-only solutions (look in the end of the mb6582 photo tutorial) - you haz many options!

Greets and don´t worry too much!

Peter

3

So I built the optimized power supply and plugged it in.

I had the led connected and it glowed for a second and then went out. I measured power on the board and there’s none. I also measured at the plug end (the part that plugs into the optimized power supply from he commodore PSU) and there’s nothing there either. So it looks like my commodore PSU is kaput. Is this a regular occurrence? Is it fixable? Or should I go ahead and buy another PSU. I see there are replacement ones on eBay. Would anyone recommend them?

Thanks in advance, and I hope someone can help!

Karl.

Fee-fi-fo-fum!

I smell the blood of an Irishman.

That’s 3 confirmed Irish posters on the forum.

I used to be the only Irishman in the village at one stage.

Welcome.

Getting back to your question:

I was only thinking about the 2 rails provided by HDD power supplies lately.

The only issue though is that it puts out 12V DC and not 12V AC which is what the original C64 puts out.

I think you may need to remove or bypass the Bridge Rectifier (B40C800) in the Optimized PSU.

I remember asking one of the guys in the chat, if passing DC current through a Bridge Rectifier can be problematic,

and if i remember correctly, it can cause problems.

Maybe someone can confirm this.

Another thing is that those cheap PSU’s tend to get pretty hot,

at least my one does when I have a 3.5" hdd hooked upto it.

You might be better off going for a c64 PSU which can opened like the wedge shaped ones.

The components can be replaced in those ones.

I’m not sure if this one is can be opened, maybe someone else can confirm this too.
![$(KGrHqMOKkME6UjqGohTBOrZl,G7N!~~60_12.JPG](http://i.ebayimg.com/00/s/NzY4WDEwMjQ=/%24(KGrHqMOKkME6UjqGohTBOrZl,G7N!~~60_12.JPG)

4

P.S.

I hope you’re not building solely to get the Blade Runner sound you were obsessed with! :thumbsup:

Hehe.

5

Ha ha. The world is too feckin small! I found a nice synth for brassy sounds, a Yamaha SK20. It has a nice band pass filter on it. Was that you who mentioned the midibox on that thread? If so, thanks a million. I’ve been having mucho fun putting it together and designing my CS. It’s pretty addictive…

I saw that dude selling the replacement PSU on ebay you linked to. I’ll probably pick it up if it stays at that price. You reckon the replacement ones from the states are fairly crap? I figured they might be.

I feel like maybe building my own based on one of the designs here.

Thanks for the suggestions Hawkeye. I’ll have a look through my options tomorrow. I might buy a replacement for now, just to get things up and running, with a mind to building a more permanent solution for the final complete CS.

I’m glad it’s nothing serious anyway. If it had happened further down the line I’d have been pulling my hair out trying to find the source of the problem!

6

The power supply Smithy linked to can indeed be opened. It uses standard regulators.

7

Sweet deal. Thanks a million for that.

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Was that you who mentioned the midibox on that thread? If so, thanks a million. I’ve been having mucho fun putting it together and designing my CS. It’s pretty addictive…

Haha yep, and looks like I was totally wrong to say that you may not be willing to build your own!

Really glad you came all this way and are enjoying the project.

I saw that dude selling the replacement PSU on ebay you linked to. I’ll probably pick it up if it stays at that price. You reckon the replacement ones from the states are fairly crap? I figured they might be.

Those cheap HDD PSU’s do tend to heat up a bit, and are made from really low quality plastic, and you’d probably break the case trying to open it.

I’m guessing that it does work with C64’s though since they’re selling it, but since Bridge Rectifiers convert AC to DC,

it probably wouldn’t be good to supply it with DC.

That particular C64 PSU would be built a lot better and you can always replace the fuse or other parts if anything happens down the line.

I remmoved the link to reduce the chances of getting outbid.

The power supply Smithy linked to can indeed be opened. It uses standard regulators.

Thanks for the confirmation.

9

Cheers Smithy. I won the auction. Not too bad for 7 euro. Now I just have to wait impatiently for delivery…

10

Ok, so the new PSU arrived today. Pretty quick postage.

I measured the voltages on the optimized power supply. Something strange is going on. I’m getting a reading of 4.9V on the 5v pin and 5.1V on the 14V pin.

Not only that, but the 25V 2200uF cap gets pretty hot, and after a while the power goes down. For example, the led that I have plugged onto the led pins gradually fades and when I measure the 5V and 14V pins the multimeter decreases until it reaches nil.

Does anybody know what the cause of this could be? I’ve followed this walkthrough to the T. The only thing that is different on mine is that instead of using the B40C800 bridge rectifier as per the uCApps schematic, I used this one.

All solder traces etc seem to be fine.

11

The suspense is killing me!

I’ve double and triple checked everything. No idea what’s going wrong here…

12

Not only that, but the 25V 2200uF cap gets pretty hot, and after a while the power goes down. For example, the led that I have plugged onto the led pins gradually fades and when I measure the 5V and 14V pins the multimeter decreases until it reaches nil.

This suggests that the capacitor is reversed or faulty.

13

Cheers. It’s not reversed, so it may be faulty. I have another one I can try so I’ll give it a go and report back.

14

Ok. I replaced the cap. Same problem, so it’s not that…

15

Ok, check ALL connections using a continuity tester, making sure that there are no shorts or breaks in the circuits.

Check that the C64 power supply is supplying +5V DC and 9V AC as it should.

Also make sure that ALL components are the right way around, the number of times I connected voltage regulators backwards before I learned is unbelievable.

There is a fault, you just have to find it. Don’t be tempted to look for the fault with power on as this will likely do more damage and make the original fault harder to find.

Hope that helps.

Tim.

16

Cheers. I don’t have a continuity tester so I can’t really do that. The C64 PSU is supplying 5.05V DC and just under 9V AC (8.7 - 8.8V). This doesn’t seem quite right, but how and ever.

The voltage regulator is definitely in the right way around. I replaced the bridge rectifier with a new one ( the same 2W10 as before).

It’s really a mystery to me now. Could it be that the rectifier is wrong. I couldn’t get the B40C800 one as recommended so I used an alternative. Other than that, I went back over all my traces and made sure that the connections are all right. There’s no crossed traces and all soldering is fine. Good joints all. All components are in the right way round and connected properly.

This is becoming a real pain.

Thanks for your help.

17

Sorted it out. I’d wired the rectifier wrongly. Now I’m getting 5.03V and 14.10V. Sa-weeet!

http://www.youtube.com/watch?v=w5MfDn_27X0

Thanks to all for their help, and thanks be to jaysus I figured it out!!

Also, Hawkeye, the directions for running a 9V to power my midi keyboard you gave me before worked perfectly. Thanks again.

18

Cool :thumbsup:

19

Also, Hawkeye, the directions for running a 9V to power my midi keyboard you gave me before worked perfectly. Thanks again.

Nice :sorcerer: Have lots of fun with it!