Does anyone have experience replacing the stock power supply (Sony/astec) with a modern build? I am in the process of recapping a PS but it's a step up from even the logic board in terms of of difficulty. If I botch it I might either send it off the Amiga of Rochester or try one of these units.

I have one of those units in a working SE/30, and I plan on buying a similar one for an empty shell of a power supply for another build. Pricey, but works and keeps the original aesthetic.

it is a good alternative when capacitor leakage has wrecked the original PCB.

some things to consider:

- bathe the PCB in some citric acid (you can buy this in powder form and add to water) the alkaline cap juices will bubble and once that has stopped, you can remove it and rinse, don't leave it in for more then 15 minutes, and you only need to submerse the PCB itself, the rest is not as important. this ensures the PCB doesnt further degrade, do make sure though that you neutralize the acid afterwards so none stays behind.
- make sure to replace all caps with high quality replacements
if you post pictures or need help, just let me know.

Arjen

Voltages are lower with the Meanwell module type replacement PSUs. When I reviewed the Baby Face PSU, I compared it to the Stock SONY and to the SEASONIC modern replacement PSU, putting voltage measurements in my spreadsheet below.

Baby Face in mine, works well. only thing not to like is all the text is upside-down.

will try the TT Design when (if) they become available again.

Don't know if I'd ever want to use one of those replacements.

They seem quite noisy.
80mVp-p for the 60-5 module 120mVp-p for the 60-12.

Would be interesting to know what the Apple specification is for ripple for the original power supply.

>> muse said:

They seem quite noisy. Click to expand...

In my review of the BABY FACE, oh yes. I had a lot of noise on the 12V rail shortly after power on, such that it even appeared on the CRT. I show that in my video with scope measurements following, starting at 23:29 below...

That's interesting, thanks for sharing.

Those things are designed for modern applications that can tolerate some ripple but generally don't play nice in our vintage machines.

>> ArjenCNX said:

it is a good alternative when capacitor leakage has wrecked the original PCB. some things to consider: - bathe the PCB in some citric acid (you can buy this in powder form and add to water) the alkaline cap juices will bubble and once that has stopped, you can remove it and rinse, don't leave it in for more then 15 minutes, and you only need to submerse the PCB itself, the rest is not as important. this ensures the PCB doesnt further degrade, do make sure though that you neutralize the acid afterwards so none stays behind. - make sure to replace all caps with high quality replacements if you post pictures or need help, just let me know. Arjen Click to expand...

>> ArjenCNX said:

it is a good alternative when capacitor leakage has wrecked the original PCB. some things to consider: - bathe the PCB in some citric acid (you can buy this in powder form and add to water) the alkaline cap juices will bubble and once that has stopped, you can remove it and rinse, don't leave it in for more then 15 minutes, and you only need to submerse the PCB itself, the rest is not as important. this ensures the PCB doesnt further degrade, do make sure though that you neutralize the acid afterwards so none stays behind. - make sure to replace all caps with high quality replacements if you post pictures or need help, just let me know. Arjen Click to expand...

I'll get more photos later. I don't know what to do with the big cap. The perpendicular leads don't exist on the new cap I have.

Re: Citrix acid. I didn't know that was safe for the PSU? I've read it's ok for the logic board but not thought it was not for the analog/psu.

You'll need to drill a hole with a small drill bit and then expose the copper with a blade either side for the solder to adhere to.

@JDW has a great video on it.

>> iantm said:

I'll get more photos later. I don't know what to do with the big cap. The perpendicular leads don't exist on the new cap I have. Re: Citrix acid. I didn't know that was safe for the PSU? I've read it's ok for the logic board but not thought it was not for the analog/psu. Click to expand...

I generally measure those buffer caps, and its exceedingly rare for them to fail, you can very likely re-use the old one. (that is my experience with hundreds of repairs under my belt) about the citric acid bath, you can use this, especially if the board is in a bad state. I use an ultrasonic cleaner, add water + citric acid until the level is just over the PCB and then turn it on. alternatively you can make the solution and just use a toothbrush to clean the board, bubbles will indicate pockets of alkaline substances.

Don't forget to rinse it afterwards, so you get rid of the acid when it has done it's job.

I'm gathering it might not be that crucial for me to recap these power supplies (i have four Sony and three Astec). I really only need 2-4. Unless there's some critical reason I'd need to recap, none of them appear to be in bad shape and I'm not seeing any weird issues after recapping the PSU and analog boards. The PSU is just that much more trouble to do!

Looks can be deceiving. I wish I had taken a photo of the green Nichicon capacitor next to the flyback on the analog board of my SE/30, it looked absolutely pristine on the outside, right up until I de soldered it with it leaking everywhere and fishy smell to go a long with it. I've also had an ELNA capacitor on a video board from a Sony BVM.. the composite input was dead, and the cap looked perfect visually, yet when tested, it behaved like a 0.35 ohm resistor and hadn't even leaked.

To be fair, I've only ever recapped one of these compact Macs, so I can't claim much experience with them. On the other hand, when I went through my Sony PSU and measured every capacitor's value and ESR individually during the recap process, I didn't find a single bad one. So I kept them all as spares...call me cheap, but if they're still in spec, why toss them out? They can be good for a quick repair or for testing,

There is no fluid-filled electrolytic capacitor that has eternal life.

This isn't a guess on my part. It's absolute fact. If you consult datasheets and white papers, you're not going to find capacitor manufacturers that guarantee an Hour rating beyond 20 or 25 years, no matter what it calculates out to be for your particular application. And that's because electrolytic capacitors really don't last beyond 25 years or so.

Even though you might argue that manufacturing technology has improved, everything in life wears down overtime and the gaskets holding in the fluid absolutely do wear out. The electrolyte either dries up or leak out.

So no matter how the capacitors look, you need to replace them if they're 25 years or older. You don't need to replace capacitors that have a solid electrolyte because nothing can leak out of those. and that's precisely why I try to replace electrolytic capacitors with other capacitor types that have a solid electrolyte, where possible.

I'd agree with that in principle, but I think it really depends on the situation. For example, I can't justify recapping my Sony BVM purely based on capacitor age. We're talking about 350-400 capacitors spread across 9 or 10 boards inside, and the cost alone would far exceed the value of that monitor. On top of that, shotgun recapping introduces its own risks in larger jobs, extra labor, potential damage, and the chance of introducing new faults. So you have to weigh up the pros and cons.

It's fine for smaller jobs but unthinkable in my example.

But the facts remain facts, regardless of the job difficulty. So in the event of a job where you have 400 capacitors, you would need to decide if its worth it. If it were me, I wouldn't recap it at all and probably even try to get rid of it. A partial recap wouldn't have much meaning, even if it did result in some seemingly good result.

But in my experience of recapping vintage Mac main units (never any monitors or anything with 400 capacitors), I have not been put in a position where I needed to make hard choices like that.

Again, no fluid-filled capacitor has eternal life. So we must use our own good judgement on how to deal with that unfortunate fact. This is not me chastising you or anyone else either. It's just reality we are all faced with, sadly.

I might be sending these puppies to Amiga of Rochester unless this recap goes well. It's far and away more difficult than the logic/analog boards. But I'm willing to give it a go.

What are the possible catastrophes that might happen if I postpone recapping these old power supplies?

>> iantm said:

What are the possible catastrophes that might happen if I postpone recapping these old power supplies? Click to expand...

Leaked capacitor fluid slowly eats through tiny PCB traces over time.

If you power the machine repeatedly with fluid all over the board, it could cause issues because it is electrically conductive. Not as bad as spilling water on a power board, but still rather bad.

>> iantm said:

I might be sending these puppies to Amiga of Rochester unless this recap goes well. It's far and away more difficult than the logic/analog boards. But I'm willing to give it a go. What are the possible catastrophes that might happen if I postpone recapping these old power supplies? Click to expand...

He does really good work.

You might just have stability issues at first especially when you add extra cards and peripherals.

>> iantm said:

I might be sending these puppies to Amiga of Rochester Click to expand...

I'll add another unsolicited +1 regarding his work, he did a great job with my IIci which I didn't trust myself to do!