NConstantinou
Badcaps Veteran
Last Activity: 04-22-2025, 01:11 AM
Joined: 05-27-2017
Location: Nicosia
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can someone help! -
IMAC A1311 820-2784 BOARD NO DISPLAY
DEAR ALL
i have the above board,, when i power on led604 does not come on. i do have PP3V3_S0, which goes across resistor R604.here i have again 3.3v,then does to led604. The lead of the LED that is connected to Q602 D-S i get 1.9v is that correct!
on Gate which is MXM_GOOD i get 0v which is connected to PCH ic.
is my problem the PCH IC!
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ultrastudio 4k Blackmagicdesign no display
i have the above device which had a problem with power supply and was fixed.
Because i do not have thunderbolt device i connected HDMI out to the system and turn on. the display has light, buttons seems to be functional, but i do not have output.
all voltages designated on board appear except VCC3V3_LC, PM_DPO_EN, VCC3V3_DPO,VCC1V2_DPO.
when i connected hdmi to monitor and i boot system it send signal to monitor and then sleep node.
can someone help!
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Unfortunately there are no PJP junctions on board as described on schematics that is why is more difficult to find out the problem.Leave a comment:
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By removing the +3VPCU and connect power supply to short side in only apply 1v 0.65A.
if i apply higher A the short on power supply disappears.
i can only apply 1v 0.65 Ampere. if i apply more amps the short dissapears.
with this setup nothing gets worm.Leave a comment:
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i did one test. i took 9v battery and i connected black lead to - on battery and + from battery to Anode of schottky and i measured cathode.
the voltage was fluctuating a little as it was on board.
that means is defective!
ThanksLeave a comment:
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Now i got the board not clicking but 5v is fluctuating a little.
i remove the Schottky. diode STPS30L60CT and between anode and cathode i get 0.121v. is this reading too low!
thanksLeave a comment:
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Changing the top258eg ic the ps is clicking and output voltages fluctuate.
on the ps there are 5 optocouplers and one is connected to ground with main capacitors. I am assuming that is the one for feedback.
I have checked all mosfet and capacitors non of them seem to be short.
can someone help!...Leave a comment:
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HP PROBBOK 450 G4 +3VPCU SHORT
HI ALL.
I HAVE M/B DA0X83MB8H0 REV:H WHICH HAS SHORT THE +3VPCU RAIL.
WHICH POINT CAN I INJECT VOLTAGE IN ORDER TO FIND WHERE IS SHORT AND AT WHAT AMPS!
I GOT A LOT OF CAPS SHOWNING SHORT.
THANKS -
Can i substitute TOP258EG with 258YN IC!
Pls advice!
ThanksLeave a comment:
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HP Z840 workstation power supply clicking noise
No power
i have the above ps which i change the TOP258eg ic.
Now i have power but is clicking and voltages are flutuating. I change all capacitors, i test all mosfets and all are ok.
i am wondering what is the value of R901! I am getting 0.5Ohms. Is that correct!
the colours look like R,R,W or silver,G Bl.
Thanks... -
you are right. very good point my apology....Leave a comment:
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No i do not have that type but this battery works on another Lenovo.
i am sending you pictures of original and compatible...Leave a comment:
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According to the diagram there is a capacitor PC331 100p_50v that is connected to the gate of PQ303.
On board there is no such a capacitor. i found one and i solder it but resistance still low onPQ303 S to G at 0.2M with the capacitor installLeave a comment:
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I REPLACED AON7408L WITH 7408 BUT STILL GET 0.2M RESISTANCE.
GROUND TO GATE IS THE SAME RESISTANCELast edited by NConstantinou; 12-17-2024, 12:05 AM.Leave a comment:
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Thanks MON2
it seems that my multimeter was defective and i notice it too late after spending a lot of time to realize it.
getting a new multimeter the resistance is as follow
PQ 305 D to S 2.4M, S to G 1.5M, D to G 8M
PQ 303 D to S 1.7M, S to G 0.2M, D to G 1.9M
PQ 304 D to S 9M, S to G 2M, D to G 7M
when i was testing PQ305 D to S the multimeter reading was increasing more rapidly than the other readings if that is telling you something.
PQ305 is 5W3502 and is before PR302.
the EC_SMS da&cl are not short. their resistance...Last edited by NConstantinou; 12-16-2024, 08:16 AM.Leave a comment:
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is it possible the charger ic maybe defective!
After studying BQ25710 i connected only battery on motherboard and i notice that the problem is on EC_SMB_CK1 and EC_EMB_DA1.
those 2 pins are connected to RPE3 pins 1 & 1 3v is fluctuating BUT pins 3&4 i get stable 3.3v.
Those EC_SMB_CK1 & EC_SMB_DA1 are the outputs of BQ25710 charger ic​Leave a comment:
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still the same problem
voltage is flutuating.
could that be the charger ic!Leave a comment:
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CAN I SUBSTITUTE AON7380 WITH AON7516!
TO ORDER AON 7380 WILL TAKE AT LEAST 2 WEEKS TO ARRIVE.
THANKSLeave a comment:
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ok i will do that but what should be the readingsLeave a comment:
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