LISA 2/10 Power Supply Blown - SF-Bay Area Help??

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Last seen: 3 months 1 week ago
Joined: Apr 29 2009 - 01:58
LISA 2/10 Power Supply Blown - SF-Bay Area Help??

While testing my recently acquired LISA 2/10, the PSU let go, filling the house with smoke. I pulled the plug while the screen was still showing a picture with data, so I'm kind a sure I did not kill anything else inside.
But know nothing much about fixing a psu.
I did do a good cleaning before I starting using the system. I was using it for a couple days before it blew.
Is there anyone in the SF Bay Area willing to help out?
If not, any suggestions as to where to post to possibly find some local help?
Thanks

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Last seen: 7 hours 32 min ago
Joined: Oct 9 2011 - 12:54
How comfortable are you

How comfortable are you cracking open the power supply and replacing all the caps. My guess is you had a safety cap go, they usually are the first to go in those kind of supplies and they smell a ton. BTW: I recommend replacing all the electrolytic and safety film caps in the Lisa supply. If your not comfortable doing that kind of work, vintagemicros sells recapped Lisa supplies pretty reasonably.

Cheers,
Corey

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Last seen: 3 months 1 week ago
Joined: Apr 29 2009 - 01:58
I opened up the PSU. It was

I opened up the PSU. It was still warm in many places. I could not see any obvious damage. All the caps look ok from the top. So one or more might have blow from the underside. That might have damaged some traces.
I am ok with soldering, but I know very little about testing PSU's after a recap. I have done 2 for some Atari ST's. Each time they blew up again when I connected the power. I got the cap polarity right with the correct values, but other parts then failed. Recapping seems to push the next failure to other components. I think fixing a blown PSU is harder to do then recapping one that still works.
That is why I was asking for some local help in getting a fix done. This a 1.8 version PSU, vintagemicro only has the 1.2 version currently.

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Last seen: 7 hours 32 min ago
Joined: Oct 9 2011 - 12:54
Strange, he usually has the 1

Strange, he usually has the 1.8.

Anyway, no matter what if you need to do this yourself, I'd replace all the electrolytic and film caps. Usually when people mess up it's that they miss a cap. I trick I have is to premark all the caps with an Orange Paint Pen. This way I remove them one at a time, being very careful about polarity and making it easier to see if I missed one. I'd also test the diodes to make sure they are still good.

As for testing, can be a little tricky but if you google there are procedures for testing the supply but you really won't know till you plug it in and check it under load. Also remember you will need to adjust the voltage pot. There is a procedure for this you can find online with google. If you can't I'll dig them up.

Cheers,
Corey

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