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Repairing a emerson M300 uni-Drive

acdc90

Hello

I have been asked to look at 1 of these which has had a power surge ?

Yes they have ordered a new one BUT that is 6 weeks away

I have taken the top off and powered it up  with out computer module 

feeding 400v 3 phaze in  and got 560v DC on rail 

but the logic 24v and 12v output power supplies are pulsing

so far i am unable to read the numbers on 8 legged ic used  to drive this supply

Has anyone worked on one of these 

Before i start traceing the circuit around this ic  

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  • in reply to geralds

    I'm hoping that   knows what he's doing in general electric terms. He's been doing it a while and posting on E14 for 5 years and is still alive.

    I sometimes fix stuff for a local agricultural engineer - they get customers with an old machine where the cost of a replacement electronic box is prohibitive or just not available.

    So like adc90, I end up relying on common sense and experience trying to fix something with no manuals and no support from the original manufacturer. 

    I think the success rate is about 50%.

    But that is way better than the alternative.

    I just fixed a big (really big) lathe for someone - manufacturer long since disappeared, it was made in Bangalore. Scary high power 3 phase control box  but they did put a schematic in the control box when they made it (about 1980). Since then people had changed things a bit without leaving any notes .

    Scrapping stuff like this is crime (at least against the environment) and the repair probably saved them about £10k v the cost of a second hand replacement.

    Sometimes it's the right thing to go for it (using nice long probes, a lot of care, and keeping one hand in your pocket.).

    MK