HP 250 G5 X0Q77ES#ABU uszkodzony RT8243AZ pomyłka w lutowaniu.

kamil1986 napisał(a): worries me a little bit the resistance at pin13 of NCP81206M is only 74Ω, is it correct resistance at this place?

Yes, this resistance seems too low.
Measure the resistances to ground on pins 1, 7, 8, 14 of chip Q21.

Measure the resistances to ground on pins 1, 7, 8, 14 of chip Q21

1. 36kΩ
7. 15kΩ
8. 4,5kΩ
13. 105Ω

Remeasured resistance to the ground on pin13 of NCP81206M now is 105Ω. I Have another same motherboard but with different CPU, there was also damaged NCP81206M resistance at pin 13 on NCP81206M is 136Ω both motherboards work ok.

What is the resistance to ground on pin 13 of chip Q21 with the reversed polarity of test leads?

What is the resistance to ground on pin 13 of chip Q21 with the reversed polarity of test leads?

Measurement with reversed leads also 105Ω

Do you have an oscilloscope?
If so, check if you have a switching signal on the transistors side of all coils.

Yes, I have an oscilloscope but the laptop stop working again. All voltages present on the motherboard after press the power button motherboards stuck at current 136mA, reflash bios did not help. +3VS is missing resistance in this line 4,2kΩ. Q21 seems to be damage. Signal SUSP# in pi5 at Q21 is in high state 3,3V no +3VS at pin 8 and 9.


Can I bypass Q21 and link +3VALW straight to +3VS, just for diagnostic purposes?

Please, specify the voltages to ground on pins 1, 3, 5, 7, 8, 10, 12, 14 of chip Q21, when the machine is turned on.

Please, specify the voltages to ground on pins 1, 3, 5, 7, 8, 10, 12, 14 of chip Q21, when the machine is turned on.

1. 5V
3. 3,3V
5. 3,3V
7. 3,3V
8. 490V
10. 490mV
12. 7,3V
14. 5V

kamil1986 napisał(a):8. 490V

Do you mean 490mV ?

Yeah mistake, should be 490mV

The chip Q21 (EM5209) seems damaged. Replace it.

I do not have this chip at the moment, can i bypass Q21 just for test and link +3VALW with +3VS.

kamil1986 napisał(a):I do not have this chip at the moment, can i bypass Q21 just for test and link +3VALW with +3VS.

Yes, you can.

Thanks, Matic. Could you explain to me one thing on the diagram signal SUSP# the (#) at the end of a signal name, that`s mean this signal is in a low state (logic 0) when is active, going this way +5VS and +3VS should present at the pins 13,14 and 8,9 when at the pin 3 and 5 are logic 0. That's confused me during diagnostic Q21 I thought KCB disabled +3VS power line because SUSP# is in the high state logic 1. Or maybe my interpretation of the diagram is wrong?

kamil1986 napisał(a):Could you explain to me one thing on the diagram signal SUSP# the (#) at the end of a signal name, that`s mean this signal is in a low state (logic 0) when is active

In some diagrams, the signal name has a "#" at the end although it is not negated (it is active at high state) and I don't know why.
In your case the signal "SUSP#" is active in high state.

Do you have an oscilloscope?
If so, check if you have a switching signal on the transistors side of all coils.

Yes, I have an oscilloscope, What exactly do you mean switching signal on the transistor side of all coils. The signal at transistors gates?

I found Q21 (EM5209) after replacing, the motherboard start working again. I do not know why but resistance at pin 13 of NCP81206M now is 156Ω before was 105Ω. Do you think this is still too low? What resistance should be in this place in kΩ?

kamil1986 napisał(a):What exactly do you mean switching signal on the transistor side of all coils. The signal at transistors gates?

No, not transistor gates. I mean the "switching node" of each DC/DC converter (picture below). No need to post all of the oscillograms, just check, if you have an AC pulses on switching sides of all coils.

kamil1986 napisał(a): I do not know why but resistance at pin 13 of NCP81206M now is 156Ω before was 105Ω. Do you think this is still too low? What resistance should be in this place in kΩ?

Yes, this resistance seems too low to me. Yes, I think it should be in kΩ range.

just check, if you have an AC pulse on switching sides of all coils.

Yes, I have pulses at all coil, was nothing at PL1203 but after boot windows and run 3d benchmark, pulses and +VCC_GT appear at PL1203. Still trying to find the source of low resistance at the +5VS line, any ideas on how to find shored element currently 156Ω is in this line.

kamil1986 napisał(a):Still trying to find the source of low resistance at the +5VS line, any ideas on how to find shored element currently 156Ω is in this line.

Have you measured this resistance with HDD, fan and keyboard disconnected from the motherboard?

If so, you can follow the schematic and remove the chips connected to this power rail one by one. The suspects are: U20, Q21, PU1101, PU1502, FG1, UA1.
Check the resistance to ground on power rail "+5VS" after each chip removal from the board (the board should cool down a bit before measure the resistance). I would start with the chip UA1.

Have you measured this resistance with HDD, fan and keyboard disconnected from the motherboard?

Yes, all measurement was taken at the motherboard only with everything disconnected.

I would start with the chip UA1.

Yes, it was this chip, after replacing resistance in +5VS was increased from 156Ω to 52kΩ. I think the repair is complete, Below is a small summary of what was broken

PU1101: NCP81206
PU2: BQ24725
UC6: TPS22961
Q21: EM5209
PR1118
UK1: KB9022QD
PQ8: AON7934
US1: SY6288D
UL1: RTL8111G

I Will test the laptop now, if everything will be ok I will close the thread. And of course, I will press the help button for Matic.