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A1708 820-00840-A no image

H

hgoncalves

Active member
Hi,

I have an A1708 that only has image on external display.

Client said that it was listening music, and the display died.

Already tried 2 known good displays, with same result.

Not sure if the problem is backlight or image, but I can't see nothing on the display, even with a flashlight

PP5V_S0_BKLT_D = 5V
LCDBKLT_FET_DRV = 0V
ISNS_LCDBKLT_N = 13V
ISNS_LCDBKLT_P = 13V
BKLT_EN_R = 3.3V
PP5V_S0_BKLT_A = 5V
BKLT_SENSE_OUT = 0V
LCDBKLT_FB = 0V
PPVOUT_S0_LCDBKLT = 0V

PPVIN_S0SW_LCDBKLT starts at 0.150V and them drops to 0.050V.

Not sure if D8410 is good, because voltage is passing through both pins (I think that in diode reading it only should have voltage in one way, correct?)

Can you help?
 
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H

hgoncalves

Active member
Hi.

EDP_INT_AUX_N = OL
EDP_INT_AUX_P = OL
EDP_INT_ML_N<0> = OL
EDP_INT_ML_P<0> = OL
EDP_INT_ML_N<1> = OL
EDP_INT_ML_P<1> = OL
EDP_INT_ML_N<2> = OL
EDP_INT_ML_P<2> = OL
EDP_INT_ML_N<3> = OL
EDP_INT_ML_P<3> = OL

BUF_EDP_PANEL_PWR_EN = 0.718
EDP_BKLT_PWM = 0.786
 
2informaticos

2informaticos

Administrator
Staff member
I forgot this board has series capacitors for data lines.
You should check on the other side of the capacitors.

"Not sure if D8410 is good, because voltage is passing through both pins"
I'm not sure what this means...
 
H

hgoncalves

Active member
EDP_INT_AUX_N = 0.255
EDP_INT_AUX_P = 0.258
EDP_INT_ML_N<0> = 0.256
EDP_INT_ML_P<0> = 0.260
EDP_INT_ML_N<1> = 0.258
EDP_INT_ML_P<1> = 0.258
EDP_INT_ML_N<2> = 0.259
EDP_INT_ML_P<2> = 0.260
EDP_INT_ML_N<3> = 0.259
EDP_INT_ML_P<3> = 0.259
 
H

hgoncalves

Active member
Hi.

I'll try to explain what I mean:

When measuring the diodo D8410 with the multimeter, and placing the positive tip on one of the diode pads (pad1), and the negative tip on the other diode pad (pad2), I think that current should only pass from one side of the diode (value reading in diode).

If I invert the position of the multimeter tips (the positive one on pad 2 of the diode and the negative one on pad 1), the diode reading should be 0.

This is not happening. Even reversing the test tips, I always have diode readings above 0.

Did I you understod? Is this thought correct? How do I test schottky diodos in a proper way?
 
H

hgoncalves

Active member
OK. I've mesured it onboard. That explain the reading. Out of board, I get the right reading.

However, it seams that I have a problem on PPVOUT_S0_LCDBKLT, cause diodo reading is 0.105. I think it should be higher (dont have other board to compare it).
 
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