PS dead after long storage.

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Joined: May 7 2017
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I have an Apple II sn 277 that I bought from Team Electronics in 78 (it was a demonstrator). I used it for years then (foolishly) stored it in an attic. I tried to fire it up the other day and no power. I set up a dummy load to test it with appropriate sized resistors. No outputs. I measure about 335 volts between the cathode of D2 and the anode of D1 so iguess it is working up to the FW rectifier but don't know enough beyond that. I am considering trying to fire up the computer with an old Sola Basic 83-83-3250 PS I have on hand. It has 12v .5A, 12v .5A, 5v 5A all voltages isolated. I'll use a regulator to get the -5 from the -12. The trouble is that the label on the PS says that the +12v needs to supply 18 watts which is 1.5A. What does the bare machine actually draw from the +12v line with no peripherals or cards? If needed I will buy the universal PS from ReactiveMicro. Has this thing established a reputation in the community? Also The top cover broke years ago. Is there any chance of finding one from a II? Would color matching be a problem?
Posted on another topic but no response so I'll try here.
Thanks for any help.

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speedyG's picture
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Joined: Nov 16 2011
Posts: 2376
Re: PS dead after long storage.

Hello Ulao,
welcome to the board. First of all before issueing the second posting some
patience is recommended.... the members of this board are all over the world and partially in different timezones..... so this is not a "instant service drop in shop"....
second: i`d recommend to do some research in former postings at the right top
called "search"-field and there also hunt for the topic "recap"....
next maybe a visit at:
http://www.appleii-box.de/D04_allabotpowersupplies.htm
and its followup pages might be usefull....
and related to thr top cover i'd recommend another posting at WTB or about the color
a research again at that topic "color match Apple II"...

sincerely
speedyG

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Re: PS dead after long storage.

Hi Speedy,
Thanks for the warm welcome.
I originally posted my query at:
http://www.applefritter.com/?q=content/power-supply-apple-ii-ii-another-one
When there was no response after 25 hours I began to suspect that since that issue was perhaps considered resolved maybe I should open a new topic and since there has still been no response to the original posting maybe I was right. I have spent quite a bit of time researching the power supply including the pages you mention and yes I am sure the caps will have to be replaced but in the meantime I should like to determine if the motherboard itself has problems as well before investing in a power supply if needed. I found the answer to my question about the power drain on the +12 v supply on page 107 of the Apple II Reference manual (Jan. 1978 version). As I suspected the memory is a power hog and my fully populated board draws over 850 ma but by removing all but the first bank I can get it under 350 ma so my 500 ma supply will work.
Thanks for your suggestion on color matching I shall try that.

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John Green

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Re: PS dead after long storage.

Is it the original power supply? Then that could be very valuable, if it's a silk screen toggle supply, unobtainable. There could be a few things wrong with it that would prevent it from running.

The schematics are available online, I would also suggest doing a complete electrolytic recap, checking the transformers and the bridge rectifier. also don't forget the X safety cap, they usually go up after 40 years in a smelly puff of smoke.

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Re: PS dead after long storage.

Thanks for your reply Casey,
If I remember correctly I had to replace the PS about 1980 so I don't believe it's original. It is in fact precisely the same as the PS shown in ( http://www.applefritter.com/?q=content/power-supply-apple-ii-ii-another-one#comment-83005 ) first image. I understand that I'll have to replace all caps. Please take note that this supply DID NOT fail under load so I would not consider an over-stressed semiconductor or over-heated transformer or passive component such as a resistor to have failed. Since it was subject to daily temperature cycling from say 30° to perhaps 150° F (-1 to 65 C)I would be most suspicious of something like a failed solder joint. I am not quite sure what you mean when you say x safety cap. Do you mean the big white rectangular cap on the input end of the supply?
Thanks.

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John Green

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Re: PS dead after long storage.

In the pictures in the other thread, that looks like it. The safety cap is a special cap designed to fail open. I think they are paper film and will fail from age.

Joined: Nov 20 2004
Posts: 39
Re: PS dead after long storage.

Hi Ulao,
Referring to http://www.applefritter.com/?q=content/power-supply-apple-ii-ii-another-one
If that is your PS (Aztec) then the following might help.
See image at http://www.appleii-box.de/APPLE2/powersupplies/research/Aztec%20AA%2011040B%20layout.jpg
If you have an intact fuse, and if there is DC > 200v at the output of the bridge rectifier,
then check/replace C7 (220uf, 10v). If this cap fails (it is in a hot location) then the PS will not oscillate.
Also, check/replace R3 (150K) as this might go open circuit or out of specification.

Hope that helps.
Laurie

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Re: PS dead after long storage.

The revenant. Another long dead Apple II comes back to life.

Yesterday after a week of air conditioner and well problems and using an old Sola industrial power supply (which has 2 12v and 1 5v outputs, all isolated) and a USB adapter with a 12v lead acid battery I managed to cobble together a temporary power supply that I trust to run an Apple. Powered it up, nothing. I reseated every IC I could reach and it came up. I do still have some keyboard problems. N & U don’t work L gives me multiple characters but many have improved with exercise. Another member is sending me a power supply so that should take care of that. The top cover broke years ago and I glued it together which worked for quite some time till it broke again (though not in the same place). I have subsequently lost all but one piece including the one with the logo. So my question is Could I get a cover for say a II+ then buy the name plate / logo from another source and replace the logo? Does anyone know if the covers are identical except for the nameplate?
Everything I have tested so far works. I have not tested the game port or the cassette interface (don’t have a portable cassette player). Have found 2 cassettes, Apple-lis’ner and Mastermind/Biorythm. If I come up with a cassette player I will try loading them, doubtful after nearly 40 years. As for the game port I haven’t found the paddles but back in the day I never liked the paddles so I made a joystick I suppose I can do that again.
How I issue a RUN command until I get the keyboard fixed I don’t know. I guess I’ll have to pull the keyboard tomorrow.

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Re: PS dead after long storage.

John,

Do you still need a Power Supply?

Steven Smile

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Steven (gsmcten)

"Apple ][.....It's ALIVE!!!!!"

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Re: PS dead after long storage.

Yes my current supply is as I said a rather kludged affair, adequate for testing but not a long term solution. If I could figure out how to attach an image I would show a picture.

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Re: PS dead after long storage.

Ok,

The way you were talking, you didn't sound like you needed it. I'll get it in the box and shipped this week.

Steven Smile

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Steven (gsmcten)

"Apple ][.....It's ALIVE!!!!!"

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Re: PS dead after long storage.

One Apple II Plus PS on the way!

Steven Smile

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"Apple ][.....It's ALIVE!!!!!"

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Re: PS dead after long storage.

My thanks to all who helped me get my Apple ][ working again after all these years. It's now virtually authentic.

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