I've just found the old apple ][ that has been stored away for a long time (30 years) at my parents place. I want to do a full refurb on it and am currently in the investigation and cleaning phase. It was in pretty poor condition but am working through the process now. So much great information in this forum and elsewhere on the net.
I don't want to fire up the power supply until I see if it needs the filter cap replacement and also until after i have my electrician mate cast his eye over it. I've messed about with low volt electronics for years, but I like to leave mains voltage stuff to the professionals.
So I removed the power supply, which has had what appears to be a minor oil spill on the outside which I will be cleaning up first. Inspecting it showed the rivets had been drilled out prior by someone else sometime in the past.
So I cant see any of the rectangular caps that folks have said are a problem, so this must be a slightly different version to those. None of the electolytics appear to be bulging and inside looks pretty clean. I don't know if the last person to open this has done anything untoward but I dont think so.
So my question is am I right in assuming their shouldnt be anything in there that needs replacing at this point?
Just go ahead get my sparky mate to confirm its safe then check the voltages on the connector and see what happens on powerup?
Thanks in advance for any observations and advice.
Great. Thanks for that. I have a lot of cleaning to do on it.
So I gave it a clean and had my electrician mate have a quick look over it. Nothing seems to be wrong which is good but the voltages are slightly low. I'm hoping its not too out of tolerance.
The voltages I'm getting are...
This is not under load.
Cleaned up alright, I used a stiff bristled plastic brush and Isopropyl, which removed some of the plating. Went for something gentler once I saw, but its not too bad. I was careful to stay away from the label and the handwritten ink.
Havent had much time to play at the moment but its all moving forward. Going to start a new thread with my progress.
It could be that under load the voltages stabilise - or it could be those 40 years old capacitors as usually voltages are too high with no load.
I recapped my Apple //e's PSU before even trying it to be honest. I feel that 40 years is enough for an electrolytic and that would give the PSU a longer life. If you have the tools and the skill, I can't see why not replacing them.
Another option is to give the rails a little load using resistors and test. But that's a bit cumbersome, I'll admit that. Maybe you can just power up the motherboard and check the voltages then.
I concur that upgrading your power supply with modern technology is best. Henry at ReActiveMicro.com suggested very strongly that I have my IIe power supply rebuilt with new tehcnology. So I sent mine to him for a rebuild, and it was rebuilt and sent back within a week. Or, you can buy the rebuild kit from ReActiveMicro.com and do it yourself and save some time and money if you have the skills. I don't. Good luck!
Only problem with using ReActiveMicro in this case is it'd be a six month round trip costing an additional $80USD in shipping. :-)
(Not that I'm saying "Don't Recap", but just note it'll have to be done locally)
Related, RS Components has become my "go to" place to source recapping components in Australia. Free shipping, and a good range. I used to use Element 14, but RS ended up being MUCH cheaper on the whole.
(Jaycar and Altronics as a backup, of course)
I believe ReActive actually swaps out the guts for their modern PS design. Which is a wee bit different than doing a recap yourself. If you have the skills and tools already (or have a friend who does), you can recap one of these for probably less than $10. I prefer to keep the hardware original when possible, without replacing it.
As tony359 noted, 40 years is sort of pushing the lifespan of an electrolytic cap. Plus, caps can go bad with no visible signs like leakage or bulging. I personally also don't like the fact I can see 85 degree caps in there. It can get fairly warm in an enclosed power supply. Even if temps don't exceed 85c, 105c caps give you a much longer lifespan at temps lower than 105c. For me, it's a piece of mind thing to do a recap on anything over 30 years old. Plus at my point in life, that recap will last my lifetime. And by the time they need to be replaced again, it will be someone else's problem. But I have the tools and skills, so its easy for me to say all this.
Also, I believe these are switching power supplies that should be regulated, not linear. So the voltage should be pretty much the same under load as no load. Which should be pretty close to spec.
The voltages given above are actually absolutely fine. Indeed it is not uncommon for switching power-supplies, even modern ones, to have a minimum load - so voltages can be a bit off when running idle. In a modern power-supply all four voltages would be switched and monitored separately. This original Apple II supply has a really simple design though. It only has a single feedback signal from the secondary to the primary side, monitoring the 5V supply. The other 3 voltages will therefore slightly vary, depending with the load (in fact, also with the relative load of the voltage and the 5V supply). There is no need to worry when those are only a few percent off.
ReactiveMicro's "PSU service" indeed will swap the whole old PSU with a new one - only the case will be kept.
I like the idea that my PSU is still the original one and to be honest a bunch of capacitors is not so expensive. In the UK RS Components is not my first stop anymore as you usually have to buy 10+ of each component. I use Farnell even though they tend to mess up with the shipment. Unfortunately they both have a minimum of £30 or you'll pay about £5 delivery charge.
When I swapped the caps of my PSU, I tested the old ones and most were reading at the top of the 20% tolerance, a few were completely off despite not showing anything wrong visually.
If you can solder, replacing those caps is fairly easy. Console5 offers a capacitor kit for the Apple PSU at a reasonable price - but I do not know what kind of caps they offer.
Console5 uses almost exclusively 105c Nichicon and Panasonic, which are two of the brands considered to be top tier by the general consensus. Other top tier brands include United ChemiCon and Rubycon. You may get some people who slightly disagree or prefer one brand over another, but these 4 are often top of the list. I've used thier kits in almost all of my old video gmaes and computers that they supply kits for. Saves me time of searching out the proper caps on a site like Digikey or Mouser.
I think recently Console5 has had to source a different brand for axial caps, as it seems Nichicon is getting out of the axial market. Their axials were only 85c anyway, so not preferred unless I had to use them due to fit issues. In most cases, with some creative lead bending and insulation, you can make radial caps fit in most places axials were used. On my //c, I replaced the large axial in the internal switching power supply with a radial, along with two much smaller axials they used on the main board. I've also replaced all of the axials in the disk drive with radials as well.
Seems the capacitors from the Apple // era were indeed really good (well, it was the time well before the 90s cap quality disaster...). When I checked my supply a while ago (a 1984 Apple //e), all caps were within specs (low resistance (ESR) and capacity within tolerance), so I just returned them. I somehow enjoy the fact, that it's still all original - well, except for the RIFA of course, which already showed cracks...
It's a question of believe - and an old argument. But as CuriousMarc says, you're cleary a "recapper" when you change perfectly fine capacitors... ;-) Here's his defence for "unfairly treated vintage capacitors": https://www.youtube.com/watch?v=GMNQDoFpYQY
I won't argue with any of those brands. Panasonic is usually my choice as well.
I am not suggesting the those caps will be bad. Just that after 40 years they may be more prone to fail. As a kit is only $10, I feel it's money well spent to make sure the PSU won't need to be re-opened for a long while.
I'm no EE, so if I'm speaking incorrectly, please correct me. As I understand it ESR and capacitance are only two factors that can cause a cap to be bad. There is also leakage current, which has to be measured at operating voltage (as I understand it, again, not an EE by any means). I believe in theory, that should effect ESR as well, but may not. Either way, for the peace of mind that the caps are highly unlikely to go bad for the next 30-40 years vs any one could go bad tomorrow, a week from now, or a year from now, it's worth it. I don't want to have to be tearing gear down once a year to trace down a single sporadic bad cap. One and done.
And Apple's quality choices are suspect in some cases. I many cases, I see good Nichicons. But I've seen them use some no name Chinese brands that you even have trouble finding info on today. Such as Chton and in the case of my Apple //c Colormonitor, it was chocked full of Samyoung (which at some point had some kind of partnership with UCC as they borrowed their logo, but that clearly didn't last) and Samhwa caps, which are virtually unheard of.
I had an old-ish switching PSU which was was taking several attempts to power up. A capacitor was responsible for that. It read fine with a multimeter and with one of those arduino-based tester. But clearly at 390V DC it was not ok.
And, again, the ASTEC Apple// PSU I recapped indeed had 2-3 small capacitors which were testing completely off. If the kit was $100, I may agree not to just replace everything blindly. But for $10 and also considering it's a 30 minutes job, it really feels very worth to me.
Thanks for all the feedback. Great stuff. I'm going to try run with it as it is initially and check the voltages again with it all assembled.
Down the track I reckon I'll be trying some of these suggestions.
There is nothing wrong with the voltages.In the Apple PSU only +5 is fully regulated, the other voltages are recitifed and smoothed only, their values are simply determind by the transformer winding ratio.When +5 is not under load they will always be low, as +5 is increasingly loaded and the power supply is working harder the other voltages will increase.
Don't waste your money on a modern replacement, that supply you have has worked well for over 35 years it has proven its reliability. I wonder if the modern replacement will be able to do the same.