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Hi,
I have this Power supply but don't know if is original or a Clone. Outside stands it's 115V/ 60Hz, but inside has a RFI filter 230V/ 50-60Hz
It's an A2M001 and 820-0003-01 is written on the PCB.
Thanks.
[quote=David_M]That is the power supply Apple used before the Astec supplies[/quote]
Yesterday it stopped working, no voltage through that rfi EF1 filter...
Thanks.
Sadly. a lot of older Apple power supplies need rebuilt these days. The caps in particular go bad over time. I'm not sure I'd rebuild that one due to its collectible nature. I might be inclined to store it as-is and buy a new power supply to use instead. You can go two ways on that, buy a used Apple power supply of newer vintage and maybe rebuild it if necessary or buy one of Henry Corbis's brand new ones from ReActiveMicro
https://www.reactivemicro.com/product/ultimate-universal-power-supply/
Either way I'd probably keep the original one as-is.
Well, I have some spare ones, that are more modern... but the point is having the system as much original as it used to be and time to time start it up like an old car.
By the way, any page or document for fixing that kind of Power supply ?
I only know this :
http://www.appleii-box.de/D04_allabotpowersupplies.htm but it's only related to Astec
Well, where I'd start is checking to see whether the power supply functions if you bypass the RFI filter? If so, then you somehow have to find a replacement for that part. It looks like something that was probably pretty commonly used back in those days, so you may be able to find one from another power supply, possibly from some other kind of equipment.
Also I'm assuming you've tried jumpering across the power switch. Those rocker switches often fail, so that would be the first thing to try even before the RFI filter.
Have you tried to replace that filter?
What I did is try to open that filter, now I know I’ve shouldn’t done that...So need to get a new one.(already ordered). I tried to overpass that filter but was through the switch but didn’t work so may be there could be the problem. I’ll Try it today through a direct connection to the coil.
thanks
I checked the voltage throug the filter and is 130V also the switch so I connected it and no 12/5V on the other side...
The schematic is in the Reference manual. This supply is difficult to repair since I could not find the Bill of Materials or component layout drawing.
I measured voltages between the 2 ohm cemented wire wound m resistor and was 0V. I changed it for a 2.2 Ohm(couldn’t find exact value) Now The psu is ticking anytime Is switched on. Voltages are around 5 V but decreasing .
Was there a load on the power supply when you measured the 5V? To improve effeciency, some power supplies will not regulate unless there is a small load on it.
BTW, if you still have the power supply open, can you tell me what the value of the top left horizontally mounted resistor is? (It is near 2 ohm resistor, R1). It is burnt on my A2m001 supply that I am trying to repair.
I replaced all capacitors, the problem still exists. Ticking and variable voltage...
[quote=drakepirate]
I replaced all capacitors, the problem still exists. Ticking and variable voltage...
[/quote]
Have you metered all the resistors to make sure none of them show open or dead short?
If they are all good, then I might consider replacing all the diodes next.
[quote=Cordy]
Was there a load on the power supply when you measured the 5V? To improve effeciency, some power supplies will not regulate unless there is a small load on it.
BTW, if you still have the power supply open, can you tell me what the value of the top left horizontally mounted resistor is? (It is near 2 ohm resistor, R1). It is burnt on my A2m001 supply that I am trying to repair.
[/quote]
That was the problem, without load, variable voltages and ticking...when you connect it to the motherboard, it finishes ticking and everything is fine...
I replaced all capacitors and the RF filter, for nothing...
Thanks for your help!
Replacing the caps was probably not for nothing. More like preventative maintenance as most of them it is more of a when they will go bad and not if.
You might want to refer to my post here: https://www.applefritter.com/content/my-apple-ii-rev-0-psu-info
I replaced all the electrolytics in mine, put an EIDE drive as a load on the +5 and +12v outputs and it was not enough of a load. The older IDE drives would load both of these supplies far better IMO. I used some 10 watt power resistors when testing mine, 4.6 ohm on the +5v and 34 ohm on the +12v. Worked great as a test load , I could have gotten by with half that on the +5v supply.
I had to cleam my On/Off switch first, as it was oozing goopy stuff and showed no continuit when "on". After cleaning it was fine.
These supplies are very robust and it is highly likely to only have bad electolytics after 45 some-odd years. I've had mine that long and it worked up until I last fired it up in 2014. This past April it had no voltage outputs when plugged into the motherboard.
One thing of importance, since you've replaced the caps (and they definitely need to be low ESR caps), is to make sure that you put a resistive load on the +5v and +12v supplies before turning it on, otherwise it will just chirp, which is s ign of it turning on and off due to no load.
The +5v supply should have at least 500-600 mA load and the +12v about a 350 mA load.
Let me know if you have any questions.
If the resistor near the 2 Ohn is directly behind the 470uF/6.3v cap it is a 1.2K 5% 1/4 watt resistor. Or, if it is the horizontal resistor that sits just left and midway between the 470 uF/6.3v cap and the full-wave bridge rectifier it is a 10K 5% 1/2 watt resistor.
If you could be more specific with it's location I can tell you more accurately as I have virtually all components of this early PSU identified.