Re: Trying to diagnose fault on dell LA-9104P board
So resistor 1 of the divider measured 160k, schematic showed 232k, and resistor 1 did show 19.55volts on vin side.
Resistor 2 measured 46k and in schematic showed 49.9k
But with those resistance values I would of expected the voltage to be be 4.36 volts instead of 2.62...
NickyD-
Member
Last Activity: 10-21-2020, 10:42 AM
Joined: 04-04-2020
Location: Williamsburg, Virginia
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Re: Trying to diagnose fault on dell LA-9104P board
I'm sorry. But check which one...Leave a comment:
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Re: Trying to diagnose fault on dell LA-9104P board
I measures p2 at the source side of Mosfets pq100 and pq101 both 19volts.
I measured Acoff and pin 27 of the kb9012qf chip and got no voltage. I also checked all pins labeled vcc of that chip and didn't find any voltage either...Leave a comment:
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Re: Trying to diagnose fault on dell LA-9104P board
here is a pic of schematic im referencing...Leave a comment:
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Trying to diagnose fault on dell LA-9104P board
this board does turn on at all, no light nothing.
I'm finding that the gates of PQ114 are not being turned on, has no voltage on the pins.
so i then went to measure voltages of PU100 and found
pin 22 dcin: 19.27 volts
pin 13 acok: 0 volts
pin 2 acin: 2.62 volts, which i see it needs to be 3.2+ to turn on pin 13 ACOK
pin 26 vcc: 4.85 volts
pin 21 vddp: 3.86 volts
little lost where to go now -
Re: Working on a dell LA-9104P Motherboard
Out of my curiosity, what is the purpose of having pq103 and pq104 transistors. What is their responsibility...Leave a comment:
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Re: Working on a dell LA-9104P Motherboard
Pq108 after testing in diode mode I get continuity even after trying to ground the gate with my finger or connecting gate to drain with metal still have continuity between drain and source, so I will replace both, and report back after parts come inLeave a comment:
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Re: Working on a dell LA-9104P Motherboard
Pq103 had broken pin.Leave a comment:
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Re: Working on a dell LA-9104P Motherboard
Do you know if without pq103 and pq110 on the board if It should or is safe to try booting. While I wait for partsLeave a comment:
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Re: Working on a dell LA-9104P Motherboard
With pl100 removed, pq102 does not have a short. But pq108 the 3 pins on the source side were still shorted.
Pq110 was shorted on all pins, I expected it on the 3 pins on the source side, but not drain. So I removed pq110 and the short on pq108 was gone. I reinstall pl100 and check for short and no short. So I'm assuming pq110 was shortedLeave a comment:
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Re: Working on a dell LA-9104P Motherboard
Marking piece I removed assuming I read label correctly this is where inductor was...Leave a comment:
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Re: Working on a dell LA-9104P Motherboard
Yes included image...Leave a comment:
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Re: Working on a dell LA-9104P Motherboard
Would pq103 prevent it from booting. Waiting new one as I accidentally broke 1 leg.. dont ask
Leave a comment:
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Re: Working on a dell LA-9104P Motherboard
PL100 removed
Resistance measurement: 0.2
In diode mode measurement: 0.0000 voltsLeave a comment:
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Re: Working on a dell LA-9104P Motherboard
Pc129, Pc130, pc139 were the caps I measured. My bad auto correct.
But looks like everything on the circuit connecting to battery positive is shortedLeave a comment:
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Re: Working on a dell LA-9104P Motherboard
Tell me if bad Idea. But something is shorting would pluggingac adapter in and spraying 91% isopropyl alcohol do damageLeave a comment:
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Re: Working on a dell LA-9104P Motherboard
Measuring resistance I found short to ground on pr121 current sensor. All three caps pc129 pc129 pc129 etc
When I test the battery pins on the board positive and negative terminals are shorted togather. Working on that path nowLeave a comment:
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Re: Working on a dell LA-9104P Motherboard
Appreciate the assistance. Just really started digging into board repair to try and learnLeave a comment:
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Re: Working on a dell LA-9104P Motherboard
Pin 22: 19.55volts
Pin 26: .177 volts
Pin 2: 2.62 volts
Pin 4: .140 volts
Pin 13: .004 volts
Pin 27: .106 volts
Pin 28: .106 volts
All other pins not mentioned were 0v
I measured voltage on the gates of pq114 and didnt have any voltage and when measuring resistance from pin 2 of p0100 to the gates of pq114 its OL. If I'm not mistaken I would of expected to see 200k ohms due to pr139.
Pr139 isnt marked on the board eitherLeave a comment:
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Re: Working on a dell LA-9104P Motherboard
Ok I'm measuring pu100 and on pin 26.. isnt the power input for the chip in order to work at all. Ac in is 2.62v.
ACOK is 0v and icout is .7v. Isnt icout also called vcc and is the power input for the chip to workLeave a comment:
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