(347) 552-2258 [email protected]

820-2936 keeps burning current sense resistors

Inwerp

Inwerp

New member
Waterdamage on U7000, traces to R7021, R7022 were corroded away, both burned to megaohm resistance.
After replacing ISL and both resistors i got a fan spin as well as a smell of burned R7021/R7022 resistors. No shorted caps in this circuit, resistance to ground is also OK.
No shorts on charging/InRush MosFets, R7020 is also OK.
i feel dumb as i do not get why it sucks almost 0.5 Amp in CHG_CSI_N. R7005 was also replaced since it was 40 Ohm instead of 20. Could not find ISL6258 datasheet with a logic diagram, so i have no idea where should i look.
 
Inwerp

Inwerp

New member
well, it was in other repair service and i am not sure what was there before. since i removed the old chip as a first step i am not sure if it was 59 or 58.
What could go wrong if there was a wrong chip on place? both caps are replaced and repealed, they make no difference even if removed
 
Inwerp

Inwerp

New member
FUCKING APPLE
can someone tell me which ISL shoud go there? it is 6259 on the one page and 6258 on another. Unfortunately this is the only one 2936 board in my shop now
 
2informaticos

2informaticos

Administrator
Staff member
Comparing schematics for ISL258/59 with your board, should be sufficient to know which one is on your board.
Take a coffee, stay calm and you will gain time...

After U7000 is soldered, check resistance to ground on pins 17/18 and 27/28.
 
Inwerp

Inwerp

New member
i used ISL 6259 all the time, pulled from the known bad CPU board, also few fresh new chips from mouser.de , so it should not be issue. i checked CSI/CSO every time i replaced burned resistors/ISL, everything is fine there.
the thing is it looks like ISL6259 shorts both CSI_n and P lines to ground at some point, and it happens with some kind of delay, board actually posts and boots from usb stick(of course only one time since both resistors are burning away, so board stays on until power reset),
i guess there no other way to burn current sense rails.

Boardview pinout actually matches 6258 chip. but i could not find datasheet/pinout for the 6259. can someone post it?
I will try it tomorrow with 6258, just for lulz.

on page 3 (power diagram) it is 6259. on page 48 its 6258, all other pages are also 6259.
 
2informaticos

2informaticos

Administrator
Staff member
Don't waste your time with ISL6258!!!
Your board needs ISL6259; didn't compare the U7000 layout (from your board) with schematic?

Did you put correct value for R7020/50 (20/10 miliohms)?
Pull off C7021/22, not really needed...
 
You must log in or register to reply here.
Top