I got interested in DIY audio a little over 10 years ago. Around that time I came across the First Watt F5 and got hooked on building it. Where I was it took me some time to get boards, components and heat sinks. Then life happened and it all got shelved. Life has now un-happened and I am looking at finishing this old project.
I still have the components from then, including 10+ year old Rubycon 15000uf 63V capacitors. They look physically good and seem to test fine using a multi-tester, just wondering if it would be fine to use them given they've not been used at all for so long.
I damaged a few in de-soldering them from a partial build, scoring the outer cover. I can fix the damage using heat-shrink tubing and/or electrical insulating tape - would that be OK?
I'd acquired PSU boards at the time but now realize that they only allow for 30mm dia capacitors, while I have 35mm dia capacitors. The solution to this is,
1) Put four under the board and four above. I don't think electrically this would be a problem. Not sure about the look or if it affects the board mechanically. I would use a 160mmx120mm aluminum sheet under the capacitors bolted to the board and on spacers so the capacitors are not sitting against the enclosure. Still have to build that, so no pics of that.
or
2) Buy new capacitors. Right now I can get capacitors from Cornell-Dubilier.
or
3) Buy the PSU board from diyaudiostore.
With delivery to South Africa, option 2 and 3 are about similar in cost. I've attached pictures of the damage to the capacitors and the layout I mentioned in 1.
Any suggestions/advice is most welcome.
I still have the components from then, including 10+ year old Rubycon 15000uf 63V capacitors. They look physically good and seem to test fine using a multi-tester, just wondering if it would be fine to use them given they've not been used at all for so long.
I damaged a few in de-soldering them from a partial build, scoring the outer cover. I can fix the damage using heat-shrink tubing and/or electrical insulating tape - would that be OK?
I'd acquired PSU boards at the time but now realize that they only allow for 30mm dia capacitors, while I have 35mm dia capacitors. The solution to this is,
1) Put four under the board and four above. I don't think electrically this would be a problem. Not sure about the look or if it affects the board mechanically. I would use a 160mmx120mm aluminum sheet under the capacitors bolted to the board and on spacers so the capacitors are not sitting against the enclosure. Still have to build that, so no pics of that.
or
2) Buy new capacitors. Right now I can get capacitors from Cornell-Dubilier.
or
3) Buy the PSU board from diyaudiostore.
With delivery to South Africa, option 2 and 3 are about similar in cost. I've attached pictures of the damage to the capacitors and the layout I mentioned in 1.
Any suggestions/advice is most welcome.
The heat damage isn't a problem at all, just don't let anything touch those areas.
Use a couple of layers of tape over those spots, or heat shrink if you have some.
Since it sounds like you have plenty of room, use the board and capacitors that you have now.
If possible when the board is completed, test it by raising the input voltage slowly
to reform the capacitors. Once it is up to nominal, let it cook for a couple of hours.
Even though they have been on the shelf for over ten years, they should be ok.
Use a couple of layers of tape over those spots, or heat shrink if you have some.
Since it sounds like you have plenty of room, use the board and capacitors that you have now.
If possible when the board is completed, test it by raising the input voltage slowly
to reform the capacitors. Once it is up to nominal, let it cook for a couple of hours.
Even though they have been on the shelf for over ten years, they should be ok.
Thanks.
I don't have a bench power supply or a variac. Is there any other way for me to vary the input voltage?
Following the schematic the mains will feed into the 230V transformer that will run 18V ac through a bridge rectifier into the capacitors. They will be getting 24/25V dc max. I will be using a bulb tester on the mains but I don't think that would be enough to vary input voltage to the capacitors.
I have large high power resistors to connect across the output to drop the current and can monitor the current with my tester. Since the capacitors are rated at 63V, but the power supply goes to less than half that, 24/25V, would it be fine to reform the capacitors by letting the power supply run at 24V dc for a few hours?
I don't have a bench power supply or a variac. Is there any other way for me to vary the input voltage?
Following the schematic the mains will feed into the 230V transformer that will run 18V ac through a bridge rectifier into the capacitors. They will be getting 24/25V dc max. I will be using a bulb tester on the mains but I don't think that would be enough to vary input voltage to the capacitors.
I have large high power resistors to connect across the output to drop the current and can monitor the current with my tester. Since the capacitors are rated at 63V, but the power supply goes to less than half that, 24/25V, would it be fine to reform the capacitors by letting the power supply run at 24V dc for a few hours?
Wouldn't Sweat the Accidental (touched it with your Soldering Stick at some point .. I've done that a couple of times 🙂
Simply a heat shrink Labelling cover . Some respected Builders strip that sheath to Polish the Cans to a mirror finish .
Half or More of Audio is Bling .
So don't overthink it.
A simple Light bulb in series circuit with the Mains and Transformer is all the V reduction you should need.
Reforming takes a ~ minute.
Did when I had to do it.
Get on with it.. the resultant Firstwatt sounds Are worth it.
Simply a heat shrink Labelling cover . Some respected Builders strip that sheath to Polish the Cans to a mirror finish .
Half or More of Audio is Bling .
So don't overthink it.
A simple Light bulb in series circuit with the Mains and Transformer is all the V reduction you should need.
Reforming takes a ~ minute.
Did when I had to do it.
Get on with it.. the resultant Firstwatt sounds Are worth it.
You can 'reform' the caps that way. Probably just a few thousand ohms to limit the current so you can 'trickle charge' the caps and you can monitor the drop in voltage across the resistors.
Yess absolutely .. Thought on including that in my above comment, but assumed that was obvious.. mebe not ?
Thanks.
I am also building the Passlabs B1 for which I have acquired a 24V power supply on which output can be varied from 0-24V DC. I am thinking of using that to reform the caps and proceeding from there.
I will be covering the exposed bare metal of the capacitors using insulating tape and have no intention of letting it touch anything.
I did look at drilling new holes in the PCB, but whichever way I move the caps they will overlap with other components. So I will need to go four under and four above.
One thing I forgot to ask in my original post. I have a 230V, 400VAC transformer with a 11A, 18V-0-18V output. The transformer has two leads for input and four for output. In the schematic for the PSU it expects 4 input leads, two of which are connected through a thermistor. I obviously can't do this. Should this be a concern? Can I compensate for this elsewhere in the circuit?
I am also building the Passlabs B1 for which I have acquired a 24V power supply on which output can be varied from 0-24V DC. I am thinking of using that to reform the caps and proceeding from there.
I will be covering the exposed bare metal of the capacitors using insulating tape and have no intention of letting it touch anything.
I did look at drilling new holes in the PCB, but whichever way I move the caps they will overlap with other components. So I will need to go four under and four above.
One thing I forgot to ask in my original post. I have a 230V, 400VAC transformer with a 11A, 18V-0-18V output. The transformer has two leads for input and four for output. In the schematic for the PSU it expects 4 input leads, two of which are connected through a thermistor. I obviously can't do this. Should this be a concern? Can I compensate for this elsewhere in the circuit?
Sounds icky. You could make new cap boards from perfboard and wire them point to point underneath? Or no boards...
I did consider that, just run wires from the caps to the board, but I would still have to put the caps under the board since I don't have space in the enclosure to put them elsewhere. That brings a whole lot of other work I would have to do to secure the caps and board.
I prefer the funky (I think this suits better than icky 😉) option, minimises extra work and worry.
I prefer the funky (I think this suits better than icky 😉) option, minimises extra work and worry.