820-00165 PPBUS_G3H : 0V

[VinceLx2]

Hi,

On this board, initially PP3V42_G3H and PP1V2_S5_SMC_VDDC were shorted (voltage was 2.6V then). I had to remove SMC to figure it out, which I soldered back, but still PP1V2_S5_SMC_VDDC was at 0V.

So I have now:
PP3V42_G3H : 3.4V
PPBUS_G3H : 0V
PP1V2_S5_SMC_VDDC : 0V

PP3V3_S5_SMC_VDDA : 3.4V
SMC_RESET_L : 3.4V

Should I replace the SMC, or are there other checks to be done before?

 

[2informaticos]

Check diode mode to ground at 1V2_S5_SMC.
Test with known good SMC.

 

[VinceLx2]

With old SMC on PP1V2_S5_SMC_VDDC in diode mode I have 0.52V; with brand new one I have 0.51V.
Otherwise still 0V under power

 

[2informaticos]

SMC must generate that voltage.
Check all voltages on U5000 (2 OF 2), page 37.

 

[VinceLx2]

Here they are:
SMC_RESET_L : 3.4V
SMC_WAKE_L : 3.1 V
SMC_CLK32K : 0V
SMC_EXTAL : 0V
SMC_XTAL : 0.4V
VBAT, VDD (L5001-1) : 3.4 V
PP1V2_S5_SMC_VDDC : 0V
VDDA (L5001-2) : 3.4 V
PP3V3_S5_AVREF_SMC : 3.3V
GND_SMC_AVSS : 0V
SMC_TCK : 3.4V
SMC_TMS : 3.4V
SMC_TDO : 3.4V
SMC_TDI : 3.4V

Seems OK?

 

[2informaticos]

Try another SMC.
Be sure to solder it properly...

 

[VinceLx2]

This is the photo where the SMC should stand. There were some liquid damage, so I cleaned it but now there are stained conductive traces quite close to the soldering balls. Do you think it is manually feasible to solder an SMC here? Or there are hidden shorts when the SMC is in place and it is the reason why I don't manage to have it working?

I tested all the voltages from the previous post directly on the balls and it is ok, the traces are fine

 

[2informaticos]

I can't imagine how did you scratch the board to let the traces uncovered in such way.
You should be able to solder another SMC using 0.3mm balls.

You can't get 1V2_SMC directly on the pads; this voltage is generated by SMC itself, for internal use.

 

[VinceLx2]

Yesterday I watched a video from Louis, "How not to replace an SMC". He mentioned that SMCs should be taken only from donor boards, because new chips were not programed. This was 7 years ago. I bought the new SMC I used for this board on Aliexpress last year. Is it still the case that new SMC chips are just sold "empty"? This may explain it does not work?

 

[2informaticos]

Ooops, didn't expect such error; you didn't specify have used new chip.
Get the SMC from donor 00165 board; is the better election.
Anyway, you can use one from other A1466 2013-2017, or A1502.
You can easily reflash it, once booted.

 

[VinceLx2]

Ok, learning every day!
Very good to know that I can use SMC from older boards at least for testing.
I have another question about this board. As I mentioned in the first post I have PP1V2_S5_SMC_VDDC : 0V but also PPBUS_G3H : 0V. Am I correct that PPBUS_G3H : 0V is another issue not linked with the SMC? My understanding is that SMC and ISL6259 should both start at the same time, with PPBUS_G3H reaching 8.2V, then when they communicate PPBUS_G3H : 8.6V, true? If so I have another problem with this board

 

[2informaticos]

SMC needs only 3V42_G3H to start.
PPBUS_G3H will be adjusted to correct value once SMC can talk with ISL6259.