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#1 |
New Member
Join Date: Jan 2016
City & State: Cork
My Country: Ireland
I'm a: Knowledge Seeker
Posts: 6
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![]() As this is my first Thread I would like to welcome everyone and apologize for my English.
I have my testing laptop Acer Aspire 5551 with motherboard NEW55 LA-5912P Rev: 1.0. Short story of this laptop. Laptop worked fine till I wanted add some ram and did not want to power up. After diagnosing I reprogrammed bios and found out that PQ31 had strange measurement outcome so I replaced and luckily laptop came back to life. There were still defects like there was no battery charging, U70 got very hot and laptop turned off after a while. To make things worse, by mistake I made short in the charger PU5. Now laptop does not give any sign of life. I made measurements on the B+ rail. Given voltage from power supply: VIN 19V Current uptake in ST-BY: 0V No volt. on main coils 3V\5V PL3 \ PL4. Resistance to ground: PL4( 50 i 30 KΩ i PL3 (1.6Ω) PL1- 19V PU1 (LM393): leg.1 – (PACIN) 1OUT, 3.13V leg.2—RTCVREF, IN-, 3.28V leg.3—VIN, IN+, 3.60V leg.4 - gnd leg.8- VS vcc, 18.30V PD1 Zener diode: K 3.13v, A 0V PD2: K 18.35V A 18.98V PQ1 : (TP0610K): D 18.32 V, S 17.80V, G 17.63V PU2: (GT920 T24): Vin 17.80V Vout 3.28V PU3: Vcc 0V , rez 53KΩ PQ3: Dren Line B+ 0V ,PR34 0V I will be very grateful for any suggestions on where to make measurement and what value I should expect to locate the culprit. |
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#2 |
New Member
Join Date: Jan 2016
City & State: Cork
My Country: Ireland
I'm a: Knowledge Seeker
Posts: 6
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![]() Anybody have any suggestions where to start ?
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#3 |
Badcaps Veteran
Join Date: Dec 2012
City & State: kuala lampur
My Country: pakistan
I'm a: Knowledge Seeker
Posts: 1,263
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![]() try check battery connector if got any voltage
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#4 |
Senior Member
Join Date: Oct 2010
City & State: Palangkaraya, Central Kalimantan
My Country: Indonesia
Line Voltage: 220VAC 50Hz
I'm a: Knowledge Seeker
Posts: 771
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#5 |
New Member
Join Date: Jan 2016
City & State: Cork
My Country: Ireland
I'm a: Knowledge Seeker
Posts: 6
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![]() Much appreciate your help! As soon I do as you suggested I come back with the outcome.
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#6 |
New Member
Join Date: Jan 2016
City & State: Cork
My Country: Ireland
I'm a: Knowledge Seeker
Posts: 6
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![]() Not good news
![]() Removed PJ1 and did short-test , KBC got hot in 2.2V. Also, by supplying vin 19V PQ31 got hot so I removed from the circuit. I have a feeling that it will be a big challenge to make this board working but at least I can learn a lot. |
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#7 |
New Member
Join Date: Jan 2016
City & State: Cork
My Country: Ireland
I'm a: Knowledge Seeker
Posts: 6
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![]() I found short on PL26 and PQ3 \ PQ17. After exchanging short gone in this branch.
Current values with supply 19v on PL26: Current intake: 0v PQ5 : 19V on Drain 1.10v PU4 l.8 VIN 0v PQ55 – shorts G to S. PL1 19V PL2 0V 1.6 M Ω Pd17 C 18.33v A 14.85v PD13 A19V C19V PD3 C17.82V A 0V PD1 C3.18V A0V PD2 C18.38V A19V PJ23 19V PL15 19V PQ31 – replaced. Values on +3VALW: Short on PJ1 in direction to EC ENE U26 (getting hot). Values on U26: VCC leg.9,22,33,96,111,126 -- 02.1 Ω AVCC leg.67 02.3 Ω ACIN leg,127 –55.2 Ω SPICS leg.128-- 08 Ω Coil L84 02.3 Ω Could anyone advice if U26 is definitely for exchange or it can be something on the way? Could anyone advice how to remove smd coils not damaging them as I did. |
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#8 |
Member
Join Date: May 2016
City & State: Athens
My Country: Greece
I'm a: Knowledge Seeker
Posts: 69
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![]() PQ14 (4407A) is your problem... Change it and it will power up just fine
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