ACER ASPIRE 5733 Voltage flactuating

[String2016]

Hi friends, I need help on this ACER Aspire 5733 LA-6582P PEW71.The problem with this is dead laptop when i check in bench lab it shows from 100miliams to 200 then goes down fluctuating.When i check on the dc in 19v ok and on the first switching mosfet PQ59 both sides have 19v but on the second mosfet PQ52 source side ok have 19v but on the other side which is drain voltage flactuate from 15v drom to 11v then goes to 15 and dropping,the same also on the resistor PR351 with a mark R020 both sides voltage flactuating from 15v to 11v. Anyone can help me please need advise on this please

[SMDFlea]

Re: ACER ASPIRE 5733 Voltage flactuating

change PQ52

[String2016]

Re: ACER ASPIRE 5733 Voltage flactuating

replaced pq52 same value mosfet but still the same on the 4pins drain side fluctuating voltage.anyone please help on this

[String2016]

Re: ACER ASPIRE 5733 Voltage flactuating

i think i found the problem its U17 the isl chip is shorted ill try to replaced and feedback soon

[String2016]

Re: ACER ASPIRE 5733 Voltage flactuating

still the same issue i replace isl U17 and tried again still the same issue voltage flatuate on PQ52 drain side.anyone can help me on this please

[String2016]

Re: ACER ASPIRE 5733 Voltage flactuating

i change pq59 first mosfet i turns on then after i unplugged the charger it comes back to the same issue fluctuating voltage on pq52 can anyone please help me on this please

[mielta]

Re: ACER ASPIRE 5733 Voltage flactuating

Hi
Remove PR351 and check voltage
when it is stable you have an problem on B+
when not check PC248 + PC249

[String2016]

Re: ACER ASPIRE 5733 Voltage flactuating

I removed pr351 still the same problem fluctuating i checked pc248 and 249 caps no short

[SMDFlea]

Re: ACER ASPIRE 5733 Voltage flactuating

Can you check PQ59 and PQ65

[mielta]

Re: ACER ASPIRE 5733 Voltage flactuating

Change or remove to test PC248 and PC249
you cannot messure that issue

[String2016]

Re: ACER ASPIRE 5733 Voltage flactuating

Check pq59 voltages fluctuating on pin2 and 3. Done test pc248 and pc249 by removing from the board the ceramic caps are not shorted

[mielta]

Re: ACER ASPIRE 5733 Voltage flactuating

have you checked without PC248/249 ??

[mielta]

Re: ACER ASPIRE 5733 Voltage flactuating

desolder PQ65 an check fluctuating
and Messure resistance from PR353-354-361-371 are OK?

[String2016]

Re: ACER ASPIRE 5733 Voltage flactuating

you mean i will removed pc248 and 249 and checked pq59?

[String2016]

Re: ACER ASPIRE 5733 Voltage flactuating

i removed pq65 and checked still fluctuating voltages i cannot find the resistor PR353-354-361-371

[mielta]

Re: ACER ASPIRE 5733 Voltage flactuating

yes remove PC248 and 249 and check flucation

[mielta]

Re: ACER ASPIRE 5733 Voltage flactuating

PR353
PR354
PR361
PR371
see in schematics where the are

[String2016]

Re: ACER ASPIRE 5733 Voltage flactuating

done test removing PC248 AND 249 and checked still voltage fluctuating. i have to find now where is PR353
PR354
PR361
PR371 and already checked the schematics but i cannot find on the board i will check again

[SMDFlea]

Re: ACER ASPIRE 5733 Voltage flactuating

I removed pr351 still the same problem fluctuating i checked pc248 and 249 caps no short

Which side of PR351 did you test , pins1+2 or 3+4 .

[Stevie2001]

Re: ACER ASPIRE 5733 Voltage flactuating

still the same issue i replace isl U17 and tried again still the same issue voltage flatuate on PQ52 drain side.anyone can help me on this please

I noticed isl chip board give this common issue.
Isl chip has 1pin gnd rest of the pin is not gnd do this get multi-meter put on continutiy mode and put black on gnd and swipe the red accross all pin of isl pins ignoring the gnd pin se if any pins beep if they do beep investigate from their were beep coming from track it.

Make sure no power is on.

Check isl datasheet for pin layout output.