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Brusa NLG513 Repair

1789 Views 0 Replies 1 Participant Last post by  WolfTronix
I had a Brusa NLG513 Charger come in for repair with the following error message:

ShortCirc PwrSt: ERR
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So obviously it has a short circuit in the power stage. ;)

So I took it apart and checked all the IGBTs and diodes in the power stage...
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All tested good...

I then contacted Brusa to see if I could get any info on how the charger determines that its power stage is shorted... They where less than helpful (no user serviceable parts, etc...). ;P

So next I put the charger back together and powered it up with the cover off...

I noticed that the +15V supply LED was not lit (they have an LED on each power supply rail), which is infinitely more helpful then Brusa customer support. ;D

Measuring across the +15V rail, was showing a short circuit.

Given than there are lots of parts on the +15V rail, it would not be possible to unsolder each one and check for shorts, so I did the next best thing...

Set my bench power supply to +15V and hooked it up to see if I could blow the short open:
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1A... still shorted...
2A... still shorted...
3A... still shorted...
4A... This capacitor let the magic smoke out:
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Removing the capacitor, and testing showed that it was shorted:
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And now the +15V rail was no longer shorted. :)

Since this was one capacitor in a bank of capacitors for the +15V rail I felt comfortable powering up the charger.

The status page now showed: ShortCirc PwrSt: OK
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The +15V supply looks like it is an intermediate supply that is used to generate the 6 isolated supplies that power the IGBT drivers.

The charger saw that its PFC stage was outputting 0 volts and thus reported that it had a short in the power stage.

It looks like this was actually a mechanical failure.
There is a phenolic block that is ziptied to the wires going to the transformer.
It looks like this block rubbed up against the capacitor causing it to short internally.

However there is no way to really know... so I replaced all the caps in the power supply bank:
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I also ziptied the phenolic block to the PCB using the holes provided specifically for that purpose. ;P


All the pics:
http://www.wolftronix.com/NLG513_188/index.htm

Video:
https://youtu.be/cr3Q5LmyCYg

And yes, I am still looking for an Brusa NLG511 charger.
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