820-00281-A Only 5v and 0.26amp not turning on

charger ordered. The older owner was using 100 watt charger but will resolder all of them together and in 2 3 days charger will arrive and re try with the charger and let you know the result
 

2informaticos

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Any charger, even 61W can help you to check power rails.
Board will not start, but main power rails must be present.
 
Unfortunately I have only 47watt charger of a lenovo. Charger will come tomorrow or after tomorrow so better to wait 2 more days and then will let you know
 
I have my 87watt charger now and was away for a while with the new and correct measurements these are the last situations. And all the components re soldered back.

F7000/1 diode mode is 0.445 and voltage is same around 0.003V
L6900 diode mode is both legs 0.355
 
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HPWR_EN* - 0.0V
MPM_PBUS - 1.06V
P_IN - 5.18V
AUX_DET - 1.28V
SMC_RST_IN - 0 .020V
VDDA - 5V
VDDP - 5V
EN_VR1 - 1.99V
SMC_RST - 0.0V
AUX_OK - 0.0V
AMON - 0.006V
BMON - 0.002V
 
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I dont understand why but when I tried to measure C6905 on diode mode it goes directly ( I have Sunshine DT-17N multimeter which is auotmatic) to read 85.9 ohm like it is a resistor but right before it gives me a short beep. Do I make a mistake at somewhere? when I measure the R6920 (when it is on board and soldered) I read the same value. Please show me a way without getting angry :) if I am doing wrong. Is it better to remove R6920 and check diode mode on C6905 one more time? I have only a 820-01237-A logic board with me that I can get some spare parts from. But I couldnt find the boardview and schematics for it.
 

2informaticos

Administrator
Staff member
I really expect to get low diode mode reading over C6905; which is not good, of course.
In such case (leaky capacitors), R6920 is probably burnt, or out of specs; it should give you 0.000-0.002 (when good) in diode mode (between its pins).

Remove C6905/6 (one by one) and check again diode mode between C6905 pads.
If still low, U6903 is bad.
 
I have removed C6905 first, and the result was same but when I removed C6906 and measured from C6905 on diode mode result is 0.575 and when I measured R6920 (soldered on logic board) it gives continues beep on resistor mode, and value is 0.3 ohm
 
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C6905 has 4.015V and the voltmeter which is located on the charging port show 5V and 0.002A but do you have a boardview and schematics for 820-01237-A imac logic board to get a new capacitor to replace C6906
 
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