820-00292 - without 5v_s5 and 3v3_s5

[Palhano]

I've been struggling with this board for days.

I'm using the schematic: 820-00134

It arrived with a short in the 12v line, I discovered it was the CA706, I replaced it and the board turned on. But it lasted a few minutes and then died again.

The Q7610 shorted, I replaced it and it didn't have the 12v from the SSD. I replaced the Q8490 and now I have the 12v_S5_SSD. But the board still won't turn on.

PP5V_S5 and PP3V3_S5 - 0, so there's no LED01

On the Q8470
- FET_EN_P12V_S5_R - 9v
- PP12V_S5 - 12v
- PP12V_G3H - 12v

I've already replaced it twice. Using model C.
U7600
- PM_PGOOD_FET_P12V_S5_SSD_K - 3.2v
- REG_VIN_U7600 - 12v
- REG_P3V3S5_VOUT_R - 0
- PM_EN_REG_P5V_S4_R - 0
- REG_P5VS4_VOUT - 0

Any help?

 

[2informaticos]

If Q7610 was shorted, an overvoltage occured on 3V3_S5 power rail.
Did you check diode mode there?

Post U7600 basic volatges: 17, 18, 4, 5, 24, 12.
Be aware, ISL62383C is known as common failure on iMac boards.

 

[Palhano]

After replacing the Q7610, I checked the L7610 line in diode mode (0.450).
The PP3v3_S5 line shorted out in diode mode (0.002). It was normal at the beginning of the tests, could it have been the Q7610 that fried something? Can I inject voltage?

I am aware of the ISL62383C, that's why I replaced it several times.

U7600 (bad measurements, probably because of 3v3_s5, right)
- 17 - 12v
- 18 - 0
- 4 - 0
- 5 - 0
- 24 - 0
- 12 - 3.2v

 

[2informaticos]

You must find the shorted component on 3V3_S5 line.
Voltage injection is the fastest way.

 

[Palhano]

Something very strange!

I injected voltage into the line, but the only thing that heats up is the component I'm touching. I tested several components, always the same problem. The thermal camera doesn't find anything, only the component itself.

I'm putting in 1.5v.

 

[Palhano]

I discovered that the short comes from PCH! =/