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Apple II - Possible PSU Issue

Bringing This Thread Back

Hello, all.

I'm pretty sure that my Apple ]['s PSU has a problem. MacTech68 mentioned popped filter caps. I still have the problem that makes nothing show on the screen, or indicate power (startup beep). The only thing that I get when I turn it on is a click/loud pop from the PSU that happens 4/10 times of powering it on. Something else that kind of gave me a laugh was that after a few attempts of turning it on, it had a constant clicking in the PSU that after about 5 seconds caused my power to go out and made me have to go flip my breaker switch. I never thought about it being a power supply problem, I believed that I fried some chips. I also managed to break half of the chips that I attempted to take out about 6 months ago. I don't know much about diagnosing PSU problems, but I'm going to open it up and post a few pictures. Maybe someone will be able to help. If it is a problem with the PSU, and I repair it, will the Apple ][ still power on even without a few critical ROM chips that I will be replacing sooner or later? Just so i would be able to know if it was a PSU problem?

Thanks,
-Hunter
 
broken chips

Without the chips it won't boot.

It may power on but nothing most likely will happen. It doesn't have any way to tell itself to access anything or do anything without chips.
 
Depending on what's missing it may do nothing at power up, or could show random characters.

I wouldn't be ruling anything out until you have a complete motherboard or know the power supply is working.

Now, if the thing was in front of me, I could probably say with certainty that the PSU is, or is not, working, in that condition.

If the keyboard light comes on, it's a pretty good indicator that it is working. If you have a volt meter.. sometimes as little as $2.00 from Harbor Freight, with battery! ;)

The black wires are ground. Stick the black probe in that one, and the others will be as indicated on the front of the PSU, +5/-5 +12/-12 ..

The PSU needs to plugged into a load to get accurate readings from it.
 
tdiaz said:
Depending on what's missing it may do nothing at power up, or could show random characters.

I wouldn't be ruling anything out until you have a complete motherboard or know the power supply is working.
Click to expand...

tdiaz

I took a look at it earlier today. It appears to only be missing the two far right ROM chips.

Looking back into this thread, they've always been missing, even before this issue.

When I turn it on, it does nothing at all. No characters on the monitor, no startup beep, no keyboard light, nothing. Nothing except for the click/pop that the PSU sometimes makes when turned on.

If you would like more insight on how this problem came to be, I would suggest looking at the earlier bits of this thread.

Thanks,
-Hunter
 
Hmmm. I'm wondering if the mains switch has failed. Seen a few of those.

I thought in an earlier post you said the keyboard light WAS illuminating. I guess that has changed? :confused:
 
MacTech68 said:
Hmmm. I'm wondering if the mains switch has failed. Seen a few of those.

I thought in an earlier post you said the keyboard light WAS illuminating. I guess that has changed? :confused:
Click to expand...

MacTech68

I see where I said that. I'm not sure, I'll check it out as soon as I can. From when I've tested it recently, I don't think it has illuminated. I may have posted that in error, still not sure though.

Thanks,
-Hunter
 
capacitors

on the underside of the keyboard depending on which keyboard revision is a board with capacitors that fail. may want to take a look there also.
 
havokalien said:
on the underside of the keyboard depending on which keyboard revision is a board with capacitors that fail. may want to take a look there also.
Click to expand...

havokalien

Although I have moved to a different issue (Nothing happening when I attempt to turn the Apple ][ on), I am still willing to fix the keyboard, thanks for your input. Do you think I would be able to plug it into my Apple //e to see if it is functional?

Thanks,
-Hunter
 
Hello, all.

I have turned my Apple ][ on, and the power light does NOT illuminate. I'm assuming that shows that the power is not reaching the keyboard? So, it may be a PSU issue?

Thanks,
-Hunter
 
HunterCupp said:
Hello, all.

I have turned my Apple ][ on, and the power light does NOT illuminate. I'm assuming that shows that the power is not reaching the keyboard? So, it may be a PSU issue?

Thanks,
-Hunter
Click to expand...

If the keyboard is plugged into the motherboard (correctly) then yes, PSU is suspect.
 
if you have a multimeter, check one of the ICs for 5 volts.

Check Pin 7 and pin 14 of a 14pin IC (NOT RAM). That is, opposite corners. Pin 7 will be ground, Pin 14 will be +5 volts. If you don't know which pin is pin 7, just check the other two diagonal pins.

If you get nothing, it's time to open the PSU. If it's NEVER been apart before, it MAY be riveted together. The bottom plate is secured by 3 or 4 screws (or rivets) along each side.

Pics (once you get it open) MIGHT alert us to the problem.
 
Did you solve it?

Hi, did you ever get your Apple II working? If not, what's the current status?
 
greycon said:
Hi, did you ever get your Apple II working? If not, what's the current status?
Click to expand...

greycon,

I never did get the Apple II working. It's still just sitting on a desk where it has been since the issue started, getting a bit dusty.

I didn't have the time to look into the issue further and basically gave up. I would love to get it working though.

Thanks,
-Hunter
 
MacTech68 said:
Not from this distance :eek:

;)
Click to expand...

Do you have any other means of communication? Skype, for example. I could set up a one-way (assuming you wouldn't want to be shown) video conference so you could instruct me in real time on what you would advise to have done. (Multi meter testing, checking individual components for visible damage, etc)
 
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