Hi,

I have a power line choke (see picture) in a monitor PSU that I feel may be faulty (as the 2A fuse keeps blowing). Firstly, it looks somewhat blackened as does the PCB I removed it from. Secondly the DMM reads the following DC resistances.

Pins 1 & 2 read 0.8 Ohms
Pins 3 & 4 read 230* Ohms
Pins 1 & 3 read 80* Ohms
Pins 2 & 4 read 125 Ohms

* indicates that the DMM resistance is never a steady reading (insulation breakdown perhaps...?)

A Google search reveals little about the part (SPI 8LE00081 5PG HI-POT) and getting a datasheet seems difficult too.

I don't have a schematic of the circuit but the bridge rectifier does appear to be OK according to the DMM's diode setting.

Any help would be appreciated.

Tnx,
Andreas

 

The reading of 0.8 ohms between 1 & 2 is about what I would expect. I would expect the reading between 3 & 4 to be the same. I would expect the readings between 1 & 3 and 2 & 4 to be at least 100 Meg ohms. It was probably burned out by a fault further on into the power supply. (Probably the switching device has gone short circuit This will be a transistor or mosfet.) When switch mode power supplies fail normally a number of components are damaged. If you do not find and replace ALL of the faulty ones it will fail when power is next applied to it.

Les.

 

If you do not find and replace ALL of the faulty ones it will fail when power is next applied to it.

Tell me about it

 

Thanks Les. I figured 0.8 Ohms would be the sort of resistance I should expect here. Thanks also for the additional information. I will check those components as well.

Andreas