Check diode mode to ground on T2 lines going to audio connector.
Compare with good board.
Compare with good board.
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820-01958-A No Power 5V and 0.10a current draw
- Thread starter CRC2018
- Start date
Think I might be getting somewhere with this one, comparing with another board I found PP1V8_G3S is showing a 40ohm resistance to ground so not fully shorted but certainly abnormal. The problem is however even if I inject the full 1.8v into PP1V8_G3S I get no current draw and nothing visibly heating under thermal cam. I've spent some time probing around the IC's which are connected to PP1V8_G3S to try and ascertain whether one of them is causing this but have come up blank. Are there any common IC's that would cause a short/problem on PP1V8_G3S before I start pulling all of them off to try and clear this issue?
Audio amplifier, U6400 in this case.
Well Audio Amp out U6400 - no change. Basically then went through the process of removing and reinstalling every other part on PP1V8_G3S until I got to the Wifi IC, After removing this the low ohms reading on PP1V8_G3s is gone and it's now reading 3Kohm.
Unfortunately this hasn't changed the behaviour of the board - it continues to stick at 5v and 0.10a current draw and is also not visible in DFU Mode.
Would it start up without the Wifi IC or is that now the reason it's not starting? Can I just swap the IC off a donor board or is something else needed?
Unfortunately this hasn't changed the behaviour of the board - it continues to stick at 5v and 0.10a current draw and is also not visible in DFU Mode.
Would it start up without the Wifi IC or is that now the reason it's not starting? Can I just swap the IC off a donor board or is something else needed?
The board can start without Wifi chip.
Do you get 1V8_G3S now?
Do you get 1V8_G3S now?
The other G3S voltages present?
No the other G3s voltages are still not present - PP5v_G3s is reading a tiny amount around 0.03V and its enable signal P5G3S_EN is still missing. I did try it once more with the charger and thermal camera and i'm seeing a tiny amount of heat from U4850 - we're talking board is 16C and this IC is 19C.
Also might be nothing but missing P3V3MAIN_PGOOD - although R7601 measures good at 100k and there is 3.3v on one side of it!
P3V_G3H is present and correct at 3V.
Also might be nothing but missing P3V3MAIN_PGOOD - although R7601 measures good at 100k and there is 3.3v on one side of it!
P3V_G3H is present and correct at 3V.
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Isolate pin 20/U7650 and check if signal goes high.
You can try changing it.
If 3V3_G3H has correct voltage (+/-10%), then U7650 should release PGOOD2 signal.
If 3V3_G3H has correct voltage (+/-10%), then U7650 should release PGOOD2 signal.