Omron VARISPEED CIMR-V7AZ21P5

Hi, I would like to repair a broken board from a Omron VARISPEED CIMR-V7AZ21P5. There are two burnt capacitors but as they are burnt I cannot find any number or code on them. Is there a way to find out the proper replacement smd capacitor?

Mmm, only decent way is to have a schematic of sorts, or a parts list, or as a last resort, to try trace out a bit of the schematic from the PCB layout, to see where those caps fit into the scheme of things..

They are in parallel, and might be a snubber across some spiky voltage, or they may be across the incoming AC mains, as part of an EMC filter, etc, etc,...until you have some idea of where they fit, its a nogo.

Even if someone out there has an identical unit and can open it to see for you, those caps are SMD and they will NOT have values marked on them.

However, even if you find what they are, I strongly suspect they will be a few more blown bits aside from those caps!

SMD ceramic caps generally blow due to - mechanical internal short, due to either poor quality cap or the PCB flexing and micro-cracks develop; over-voltage; or way to high ripple current. If any of the latter two, then I am sure some more bits also are blown..

From the PCB tracking, it does seem they are on the mains input or rectified DC output side - try to trace out the interconnections around them, also give some photos of the other side of the board in that area, so we can see what other parts are in the vicinity.

Joe

As Joe says this type of failure of a ceramic capacitor is unusual. The capacitors are connected to the end pin of a 7 pin through hole component on the otherside of the circuit board. I suspect this is the main bridge output device, bot it could be a terminal block.
What is the component on the otherside of the board? Photo nd any part numbers would be useful.

Whay is the history of th fault? e.g bang during normal operation? overload? Bang on switch on?

It could be lighning surge damage, has anyther equipment failed?

Robert G8RPI.

They blow probably after a heavy load or high temperature but I cannot be sure. I’ve done a research on the web but there is no schematics.

No other equipment fail

As suspected that is the main power module. I expect that the capacitior failure is secondary to a failure of the power module.
The unit is probably beyond economic repair. The issue is that other parts have probably been damaged and there is a high probability that if you don't find and replace all of them the new parts you did fit will be destroyed first time you turn it on.

Robert G8RPI.

My first option was to repair it but I also ordered a new one. Just a question, is there I possibility to find the capacitors by their size?

When you get the new board, look to see if there are any markings on the capacitors, the ones I have seen have a number/code marked on them, which could be a clue to the value/voltage.

Dave

Yep, I would agree, that module probably done for - An internal short in the power module could put all sorts of power voltages out on pins where it should never be, and so the caps suffered.

Ditch it - not worth repairing - even with schematics..

And No, you cannot predict capacitor values or voltage ratings from their sizes - a 50v 100nF SMD ceramic cap can be the same size as a 10v 10uf ceramic cap, etc..

Joe

Edited By Joseph Noci 1 on 21/06/2020 11:18:55