820-3437-B No charge light PP3V42 present

posarah

Member
Pin 2 on U7100 is 0.449 with C7105 and 0.445 without. Thanks, I'm using 330pf for c7116 till my extra donors arrive. R7105 is reading 23 ohms when it is a 10 ohm resistor and was reading 10 ohms when I installed it which is weird. If it was blown you would expect it to go a lot higher than just double it's value? Pin 3 on U7100 is now reading dead short, 0.00 diode mode and 1 ohm resistance to ground. I got two ISLs with my last order, not sure if I should try the second one or not since the first one seemed dodgy this one probably is as well.
 

posarah

Member
Ok I replaced C7105 and R7105 again and tried the second ISL and same thing again. Pin 1 on R7105 has 16V pin 2 nothing. C7105 nothing on both sides. U7100 pin 1 at the test pad is 5.46V.

Pin 3 is no longer reading short, looks like it was the ISL again causing that though I replaced all 3 on that line just in case. Pin 6 on U7100 is the only thing reading low ish now. .068 or 100 ohm. Is that suppose to be so low?

A short pin 2 of R7105 could could also cause it to fail couldn't it? I'm starting to think something on that side may be causing it since everything on the pin 1 side has been replaced multiple times. R7190 for example looks pretty ugly but it's only reading 1 ohm in circuit so if that was blown it should be higher than that considering it's suppose to be 0 ohm. Could it possibly be U7190? I don't believe I have replaced that yet, nor most of the components on the PP5V1_CHGR_VDDP line. R7101 is reading bang on what it should be 4.7 ohm but that does not mean there's not a issue on that rail.
 

2informaticos

Administrator
Staff member
"Pin 6 on U7100 is the only thing reading low ish now. .068 or 100 ohm. Is that suppose to be so low?"
Didn't see R7113???

Did you check diode mode to ground at pin 2 of U7100, before applying power to the board?

Your board uses U7190?
It is marked as NO STUFF in schematic.
R7190/91 also souldn't be there...
 

posarah

Member
No I saw R7113 just thought that line should be higher than that.

I did, I didn't note it down though. When I replaced all the components on the R7105 pin 1 side and replaced the ISL last, I re checked all the components surrounding the ISL on each of the ISL pins to make sure nothing was reading short, which nothing did bar pin 6 which while not technically short did make me question why it was seemingly a low value.

Sorry, made a bit of a typo there. No U7190 is not there, only components populated in that area are R7190 and R7191. I think it was the TPS51980 that I mistook for U7190 since it looked like there was a tiny bit of green to the right side pins but very faint hard to tell. But that cant be the issue as none of the lines around the ISL go to the TPS?

Are you sure R7190 and R7191 are marked as no stuff in your schematic? Mine there not, most other components are but there not. Page 70 of 120.
Confused as to why R7105 keeps blowing when there are only 3 components on that line, and they have all been replaced multiple times. Do we have a pin out on diode mode readings both board side and of the ISL itself? I had a quick google search but couldn't find anything. That would help rule out a ISL issue.
 

posarah

Member
Ah that explains why the ISLs keep dying then. R7190 has always been there. This was your typical ebay " don't know what's wrong with it we haven't touched it" listing, so they have obviously tried to repair it and saw it was not listed as no stuff and placed it there. Curious that it's not listed as no stuff in my schematic though. Which one are you using? I got mine from the usual place, badcaps. I've also got Zin Zhi Zao which also does not list it as no stuff.

If the ISL was shorted though you should be able to pick that up by testing the pads on the chip itself shouldn't you? Pin 2 is shorted at pin 2 of C7105 on the board but when I remove the ISL and re test the short is gone. But than I diode mode the chips pin 2 to ground you get .602
 

posarah

Member
Replaced the TPS51980 as it did look a bit suspect. R7105 is not blowing anymore is it looks like it was R7190 causing the issue. ISL is getting hot now so yay gotta order some more ISLs. This time I'll order more than two....
 

2informaticos

Administrator
Staff member
R7190 is marked like optional, in case of "PP5V5__DCIN:YES" version; never faced with such board.

U7100 should have some reason to get hot.
Inspect all its surrounding components; Q7130 is suspect now.
Check diode mode to ground at L7130.
 

posarah

Member
L3170 pin 1 .138 pin 2 .138. Q3170 pin 1 .138. c7125 pin 2 .137. All values are diode mode. Looking around the ISL immediate area will report back once completed, just thought I should do these first as Q3170 was originally the issue so likely is the issue again. Removed C7105 again as it was causing my meter to read OL on pin 2 of R7105. Can it be left off just for testing purposes? I do not have any other 50V caps to use.
 

posarah

Member
Yes C7125 is in place and reading fine. Sorry typed, yes I meant L/Q7130. Everything at the top immediate area of the isl is reading ok as is the left side. I’ll go through the rest tomorrow.
 
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