MSI CX500 MS-1682 - brak V_CORE

Cześć!
MSI CX500
PCB: MS-1682
Płytę można włączyć ale nie wyłączy się już poprzez przytrzymanie włącznika. Pobór prądu około 300mA.
Brak zasilania CPU. 0V na V_CORE (PL7 i PL8). CPU podmienione.
3.3V i 5V obecne, na PL6 GPU_CORE jest 1V

PU3 ISL6262
n1 0V PGOOD
n20 19V VIN
n22 5V
n27 0V
n28 0V
n30 0V
n32 0V
n34 0V
n35 0V

Brać się za wymianę PU3 ISL6262? wolę dopytać bardziej doświadczonych czy na pewno uszkodzona przetwornica CPU. Czy na n1 PGOOD nie powinno być najpierw +3V aby przetwornica prawidłowo pracowała?

Hello!

Measure the resistance to ground on coil PL7 with and without CPU connected.

Measure the voltages to ground on pins 26, 31, 36, 44, 48 of chip PU3, when the machine is turned on.

franekx6 napisał(a):Czy na n1 PGOOD nie powinno być najpierw +3V aby przetwornica prawidłowo pracowała?

No, it shouldn't. The "PGOOD" pin should goes to the high logic level after the chip starts and the output voltages are within normal limits.

Hello matic

matic napisał(a):Measure the resistance to ground on coil PL7 with and without CPU connected.

PL7 with CPU 80Ω
PL7 without CPU 12kΩ


PU3
n26 4.8V
n31 5.1V
n36 4.8V
n44 3.3V
n48 3.3V

Check, if the voltage on coil PL7 appears only for a short time, when you turn on the machine.
Also check, if the voltage on coil PL7 is present when the machine is turned on without CPU connected.

matic napisał(a):Check, if the voltage on coil PL7 appears only for a short time, when you turn on the machine.

It is 0V all the time

matic napisał(a):Also check, if the voltage on coil PL7 is present when the machine is turned on without CPU connected.

Without CPU on coil PL7 when I turn on machine appears ~0.8V next slowly drop do 0.3V and disappear to 0V

Reflash the BIOS chip. Don't forget to save the old dump.
BIOS dump is available on the forum: www.elvikom.pl/post106050.html#p106050

matic napisał(a):Reflash the BIOS chip. Don't forget to save the old dump.

Still the same problem.

Measure the voltages to ground on all coils, when the machine is turned on.

PL6 0.97V
PL9 0V without battery
PL7 0V
PL8 0V
PL1 1.2V
PL10 1.8V
PL3 5V
PL2 3.3V

Try to diagnostically heat the ATI GPU as described here.

matic napisał(a):Try to diagnostically heat the ATI GPU as described

Still the same effect.

Measure the power consumption (in mA) of the board, when the machine is turned on with and without RAM memory connected. Battery should be disconnected during the measurements.

matic napisał(a):with RAM memory

277mA

matic napisał(a):without RAM memory connected

246mA

Set your multimeter to the diode test mode and measure the voltage drops to ground on pins 37, 38, 39, 40, 41, 42, 73, 44, 46, 47 of chip PU3 with the CPU connected.

Perform the following measurements in the listed cases:
- Measure the voltages to ground on pins 17, 20, 21, 22, 46, 106, 107, 108, 112, 137 of KBC chip.
- Measure the voltage to ground on pin 4 of chip PU7.
a) Before pressing to the power button (machine turned off).
b) After pressing to the power button (machine turned on.).

PU3

37 0.38V
38 0.38V
39 0.38V
40 0.38V
41 0.38V
42 0.38V
43 0.38V
44 0L
46 0.2V
47 0.99V

a) Before pressing to the power button (machine turned off).

KBC
17 waves 0-1.1V
20 0V
21 0V
22 0V
46 0V
106 0V
107 0V
108 0V
112 0V
137 waves 0-0.8V

PU7
4 0V


b) After pressing to the power button (machine turned on.).

KBC
17 3.3V
20 3.3V
21 3.3V
22 3.3V
46 3.3V
106 3.3V
107 3.3V
108 3.3V
112 3.3V
137 3.3V

PU7
4 0.9V

franekx6 napisał(a):PU3
...
44 0L

Is this measurement correct? If so, remeasure that voltage drop to ground with reversed polarity of test leads.

Also measure the resistance to ground on pin 46 of chip PU3.

matic napisał(a):Is this measurement correct?

Yes the multimeter shows 0L

matic napisał(a):If so, remeasure that voltage drop to ground with reversed polarity of test leads.

0.49V

matic napisał(a):Also measure the resistance to ground on pin 46 of chip PU3.

0.47kΩ

Replace the chip PU3 (ISL6262ACRZ).

matic napisał(a):Replace the chip PU3 (ISL6262ACRZ)

I did not find the ISL6262ACRZ, but I had the ISL6266AHRZ, I replaced the chip and everything works.
So I click helped. Tell me which measurement suggest You to to replace PU3?

franekx6 napisał(a):Tell me which measurement suggest You to to replace PU3

I concluded that on the basis of multiple measurements.
The enable signal on pin 44 of chip PU3 was present, but the chip PU3 didn't start despite present all power supplies on pins 20, 22, 31, 48. The chip PU3 may be blocked by other control signals on pins 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, but there was no low resistance (or low voltage drop) to ground on any of that pin, so it pointed the chip PU3 is most likely internally damaged.