XR1212 - No Sign of Life

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welldigger99
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Joined: Tue Apr 23, 2019 10:46 am

XR1212 - No Sign of Life

Post by welldigger99 » Wed Mar 30, 2022 10:45 am

Hi,
Trying to repair a completely dead (or so it would appear) XR1212.
No lights, no fan, no surge relay activation.
I have the schematics, but appreciate that all this will be fairly meaningless to those without access to the same.
No output of any description on the secondary side of the transformer.
I can see 330V across the bridge rectifier (normal), so everything OK to that point.
I am assuming the problem relates to the lack of "soft start", on the IR2110 hi-lo driver, but not sure where to focus my diagnosis.
Any ideas anyone please.
Thanks in anticipation.

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Enzo
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Joined: Fri Sep 12, 2008 10:24 pm
Location: Lansing, Michigan

Re: XR1212 - No Sign of Life

Post by Enzo » Wed Mar 30, 2022 12:17 pm

SO post the schematic then.

Sounds like you have an SMPS then. Lord I hope you are using an isolation transformer for work on this. Remember the "ground" for the primary side is almost always -170vDC, so don't connect a scope ground to there. When first powered up, is there a tiny brief spike of activity and instant shut down? Or is it a brick sitting there? Check all the rectifiers on the secondary side for shorts, that will shut down an SMPS. There will be a trickle start of some sort, the controlling IC needs power to run. SO is there operating voltage across the IC? Usually either 5v or 12v.

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