820-3437 killing ISL6259(s) and I sense

G.Beard

New member
820-3437 History liquid.

Had this board working then it stopped.
Initially changed bad value resistors on pin 28 & pin 27 of ISL6259. Board worked then stopped working.
Checked current sense circuit going to pin 27 & 28 again after it stopped working and resistors bad again. ISL6259 was bad so replaced that and also replaced inrush current limmiter FET. Teted values around limmiter FET and all looks good. Turned it one, one fan spin, dead ISL6259, bad resistors again.... What should I look for here?
 

dukefawks

Administrator
Change those caps anyway. Also change Q7130 and the 6259 of course. Make sure to check both traces to the gates of Q7130 pin 1 and 6. Check R7101 and R7501 and associated traces.
 

G.Beard

New member
Change those caps anyway. Also change Q7130 and the 6259 of course. Make sure to check both traces to the gates of Q7130 pin 1 and 6. Check R7101 and R7501 and associated traces.

Ok, so I'll go with ISL6259 being ok but replaced it anyway... (Are pins 27 / 28 some sort of FET input differential amplifier or comparitor or something?)
Replaced inrush limiter, replaced the 10ohm resistors and checked no shorts and replaced caps and checked no shorts. PPBUS now working. No fan spin yet but will probe tomorrow.
 
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