Compressor Time Starting Device

[Lion_Tamer]

Hi All

I am trying to mend a rather expensive fully integrated fridge freezer which has suffered a cascade failure of the compressor starting system. Unfortunately it looks like it will be a slow process to get hold of a new TSD for this unit so I want to try and mend this one.

Embraco's Technical Information on the TSD:
https://www.embraco.com/DesktopModules/DownloadsAdmin/Arquivos/02047.pdf

The initial symptoms were that it would run the compressor for approx 5 - 10 seconds then trip the overload protector. I found that the 5uF run capacitor had failed and also then found that the MAC8SNG Triac in the "Time Starting Device" (TSD) was also short circuit, having replaced both the capacitor and triac I had the unit sat in the middle of the floor running nicely so decided to put the covers on and refit it into the housing - at this point it failed and will no longer start the compressor but just trips the thermal protector.

I have pulled the unit out again and having had a close look at the TSD I can see that one of the 0805 ceramic capacitors has broken/blown. I have reverse engineered the schematic (attached below) and marked the dead capacitor but I have no idea what value it should be, all of the other capacitors are also glued to the PCB so I can't measure them and can't get an in circuit reading.

Please can someone with more knowledge of AC circuits than me help me out with some appropriate value to try?

Thank you

Jem

[Renate]

The first thing that I'd do, is disconnect the compressor and the big capacitor and replace it with two household lightbulbs so that you won't annoy the compressor anymore when testing.

I would presume that the blown cap has to be at least 100nF to form a divider with the other cap.
I'm kind of surprised that they are using 0805 components for something like this.
Somebody with more knowledge can probably give a better answer.

[amyk]

Those are built to fail. Absurd complexity and nothing but pure planned obolescence. 

Simply replace with a generic start relay/overload protector, which will probably outlast the compressor.

Edit: are you sure the winding resistances are correct? The start winding should have higher resistance than the run.

[tautech]

Did you by any chance use a Start rated cap and not a Run rated one ?
While both are often listed as motor start caps only the Run rated ones will withstand continuous line voltage.