Apple IIc dead Voltage Converter

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CheshireNoir's picture
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Apple IIc dead Voltage Converter

Hey Folks,

I have an Apple IIc here with a dead Voltage Converter. (Not the external PSU, the internal card that slots into an edge connector).

The system is not booting with it in, but thanks to having a spare, I know the problem is the Voltage Converter, not the system itself.

I'm trying to find details (Pinouts etc etc) on this unit so I can start troubleshooting it.

It's not the same one as in the SAM's guide to the Apple IIc, to make things difficult. 

I'd even settle for just a pinout of that edge connector...

 

The capacitors look fine. Diodes look OK. (The only one that looked a bit dodgy, D10 tested fine out of circuit). Not sure what I can test without having some idea of what voltages to inject where, so I can start probing around to see what is going on.

 

Cheers and thanks in advance!

 

Chesh

 

 

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This should help 

This should help

 

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Stellar!

That helps immensely!

I should be able to rig up a suitable adapter to power it up and start seeing where it's not working.

 

Thank you so much for that!

 

Chesh

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CheshireNoir wrote:...The
CheshireNoir wrote:

...

The capacitors look fine.

...

 

About 95% of the time bad electrolytic caps look fine. I would recap it before I even bring out the multimeter.

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CVT wrote: About 95% of the
CVT wrote:
 

About 95% of the time bad electrolytic caps look fine. I would recap it before I even bring out the multimeter.

That's an ass-backwards approach.

You troubleshoot and replace bad components.

Recapping is not a panacea or magic bullet and I have seen dozens of posts with lines along the topic of  "I've recapped it but it still won't work, what's wrong?"

Or better yet "I recapped it and now it won't boot, what's wrong?"

 

 

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baldrick wrote:That's an ass
baldrick wrote:

That's an ass-backwards approach.

You troubleshoot and replace bad components.

Recapping is not a panacea or magic bullet and I have seen dozens of posts with lines along the topic of  "I've recapped it but it still won't work, what's wrong?"

Or better yet "I recapped it and now it won't boot, what's wrong?"

 

It is the correct approach in this particular case, even if the fault ends up being something else. Replacing 7 electrolytic caps takes 5 minutes max, even when you are really slow and careful. Nothing is preventing you from troubleshooting after you've done that, but in most cases you won’t have to, because it would’ve been one of the caps. Besides recapping the electrolytics is a good idea and ends up extending the life of any 37 year old DC-DC converter.

 

The reasons you have seen posts of the type "I've recapped it but it still won't work, what's wrong?" is simply due to sampling bias: when recapping fixes the problem right away, there is no need to seek help in a retro-computer forum in the first place.

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