Acer aspire D270 no power

[sasser]

hye all i details here my problem

form schematic diagram please see pages 30 from 42. 3cv and 5V system
i measure

PU3 pin 19 3v
Pin 23 no 3v
Pin 21 no 5v

PQ14
pin 4 no v
pin 1,2,3 no volt
pin 5,6,7,8 19v

PQ21 pin 5 no volt , pin 4 no volt

PD3 pin 1,2,3 no volt
PL3 no volt.

what problem here? im tired to settle this are PQ14 is culprit because no volt on pin 4 where it shouldbe 5v or PU3 itself problem

[meritosari]

Re: Acer aspire D270 no power

how about connection between pin4 pq 14 and pin 21 pu3, how many ohms when measured resistance

[whaldsz]

Re: Acer aspire D270 no power

Check the voltage of PU3:
1 -
3 -
6 -
8 -
13 -
17 -
18 -

[sasser]

Re: Acer aspire D270 no power

i will post later. before this i hear buzz sound. but i dont know from where. i tough PL3 coil then i replace from another working board still nothing. i also lifted the pu3 and put back. now no sound i hear and reading current from my PSU lab is 0.0030 means still not normal.

i will post here whaldsz the result and thanks to meritosari

[sasser]

Re: Acer aspire D270 no power

Check the voltage of PU3:
1 - 0.96v
3 - 1.98v
6 - 0.48v
8 - 3.3v
13 - 6.32v
17 - 4.98v
18 - 3.3v

continuity test pin4 pq 14 and pin 21 pu3 is ok 0.0002ohm

[whaldsz]

Re: Acer aspire D270 no power

there is a problem with your +5VPCU.

1. Check the resistance to ground of PQ35 pin 1. There could be a short.
2. Remove U25 and U23.

[sasser]

Re: Acer aspire D270 no power

hye whaldsz resistance checked on pin1 PQ35 to ground i. igot 1.86ohm without u23 and u25

shouldbe pin3 got +5VPCU right. but no volt on pin3

[sasser]

Re: Acer aspire D270 no power

on PU3 VOUT pin24 should 5v give to PL3 but no 5v here

[ktmmotocross]

Re: Acer aspire D270 no power

give it 2A 3.3V and see where is burning :-)

[meritosari]

Re: Acer aspire D270 no power

check voltage pin 21, 19 on PU3

[meritosari]

Re: Acer aspire D270 no power

boardview:

always add dash key (-) and number between 1-2 if looking a part

ex: pu3-1

[sasser]

Re: Acer aspire D270 no power

PU3 pin 19 3v
Pin 23 no 3v
Pin 21 no 5v


now buzz sound i dont know from where

[sasser]

Re: Acer aspire D270 no power

Thanks meritosari . its help me to find the component. how u get .brd format diagram?

PQ21 short on ground. pin 1,2,3 has continuity with pin 4,5,6,7,8. with on component damage? already replace PQ21 seem like short on ground and beep sound here from there

[meritosari]

Re: Acer aspire D270 no power

from china forum

I had thought the pin 19 is a little high, it should be around 1v, I have lost a record for pu3

cmiiw

[meritosari]

Re: Acer aspire D270 no power

good news

[sasser]

Re: Acer aspire D270 no power

pin 19 of pu3 below 1v is that 0.48

check PL3 to ground short both side also PC46also short on ground

[whaldsz]

Re: Acer aspire D270 no power

Lift one side of PL3, then measure resistance on both sides of PL3 with respect to ground. This will help you identify which side is causing the short - the load side or (PQ21 or PU3).

You better use bench power supply as suggested in post #9.

If you don't have bench PS and you found the problem to be located in the load side, try to remove PQ35, PC46 and PC113 and test again.

[sasser]

Re: Acer aspire D270 no power

im sorry whaldsz i dont know the technic suggested in post #9. i have PSU lab. but dont know to inject power

[sasser]

Re: Acer aspire D270 no power

Lift one side of PL3, then measure resistance on both sides of PL3 with respect to ground. This will help you identify which side is causing the short - the load side or (PQ21 or PU3).

You better use bench power supply as suggested in post #9.

If you don't have bench PS and you found the problem to be located in the load side, try to remove PQ35, PC46 and PC113 and test again.

already check resitance with lift one side PL3. left side beep on ground but one side is not

[whaldsz]

Re: Acer aspire D270 no power

which side is it? PC46? Then remove these 3 components - PQ35, PC46 and PC113 and test again for short. It could be one of them.