Repairing Start Box w New Chip

[LCA078]

Very nice. I do admire your push to replace the mosfets but before you dig too hard into them, can you post close up pics of each one? I'm dubious that all three failed in same manner as indicated by the little chip/ding/mold ejector knock out in the center. Usually a blow out is seen by melted/burnt stuff with splatter around the edges. These defects appears mechanical from the pictures above but close ups will provide more insight. Also, you might want to test the signal to each gate and see if you get any voltage... any voltage...when the box expects to power the glowplugs. If not, I seriously doubt that replacing the mosfets will change anything as they won't have a signal to allow current to flow.

For each mosfet, you should have one leg always grounded (continuity test will confirm), one leg always to power rail (24v I assume) when power rail is energized, and the gate should receive the signal voltage from the board's logic circuit and it should vary with the logic. Also, per the mosfet specs, that gate signal should be pretty close to the recommended "on" voltage.

Best of luck!

 

[Bulldogger]

Swapped in the new MOSFETs today. Also permanently soldered the IC I replaced before.
It will be a week or two before I can test and report. Going push button if this doesn’t work.
BDGR

 

[Bulldogger]

Apologies for the late update. Tested two weekends ago. The repairs were inadequate. The replacement components did not solve the problem of the lack of glow. I'll stop here and take the box apart to use for a push-button solution. I have another ESSS box I got off eBay that also did not work correctly. It's the more advanced gigantic microship style. It too will get gutted and recycled.
BDGR

 

[LCA078]

That sucks. But I think a push button gp controller is the right way to go to be functional yet simple.