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820-3437 no chime no video

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Ryanlen2

Member
Computer came in after red wine was spilled on it the night before. Inspected the board and replaced all corroded components. Then applied power and got a spinning fan without chime or video. Fan went high and stayed high. Then after cleaning a bit I noticed that traces from R5177/78 to SMC were shot. I repaired the traces here and still had the same issue. Figured if the traces to SMC were that badly burnt that the SMC was most likely fucked as well. I then replaced the SMC and the board booted normally with chime and video but no backlight. Upon troubleshooting that backlight circuit I noticed a small white dot in F7700. Tested for continuity and found the fuse was dead, as this was one of the areas hit with liquid so it wasn't a surprise. After replacing the fuse and checking for short I applied power I got very faint backlight for a split second then it went off. This caused F7700 to go dead again or maybe the fuse was bad, Im not sure. Replaced F7700 again and I now have 8.56V on both sides. Only problem is now I am back to no chime and no video.

PPBUS -8.58V
PP3V42 -3.42V
PPBUS_S5_HS_COMPUTING_ISNS - 8.58V
PPDCIN_G3H - 16.5V
PPVRTC_G3H - 3.34V
All_SYS_PWRGD - 3.3V
SMC_RESET_L - 3.34V
SMC_Wake_L - 3.3V
CPUVCORE - 1.6V
USB Mouse lights up.
Was able to PRAM with external KB before but now I cant really tell.
Is not doing 1,2,3 fan spin at the moment.

Damaged areas were U3210 area, Bottom of SMC, Q3025 area, U7090 & Q7010 area, Q7155 area and F7700 area.
Confused because everything was working before I replaced the fuse and I have a really hard time with "No video, no chime. Coincidence?

Thanks in advance. Have a good one.
 
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Ryanlen2

Member
Hi Duke.
Traces/Resistors look good although on U6100, pins 5&6 are stuck at 3.3V. Shouldn't the fluctuate, then land at 0? J6100 itself didnt have any corrosion but probe points under Q5830 were red so I replaced it as well as C5830.

U1900
pin 1 - 3.3
pin 2 - 3.3
pin 3 - .931 ( I checked with known good working and got 0.20- 0.45.
pin 4 - 0.8 - 1.1
pin 5 - 3.3V
pin 6 - 1.184
pin 7 - GND
pin 8 - .564
pin 9 - 0
pin 10 - GND
pin 11 - GND
pin 12 - .438
pin 13 - 3.44
pin 14 - 3.3
pin 15 - 1.66
pin 16 - GND

Traces to XTAL from u1900? I dont see, please advise.

Thanks Duke.
 
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Ryanlen2

Member
Sooooooooo. I think I know what the issue is but, unfortunately I dont think its a repairable one. LOL.

After not really getting anywhere with this board (mainly because I suck when it comes to anything to do with clock/bios) I decided to put it in the cleaner to get a better look at it. Well that did help because I found a tiny hole I didnt see before in (TP) PCH_CLK32K_RTCX1. I checked for continuity back to U1900 but there isn't any. The TP is too frail and I cant seem to get a wire on it. So I think Im Fucked seeing that this is the only way to access this line. Thanks anyway for your help Duke. Have a good one.
 
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dukefawks

Administrator
Dont solder a wire. Expose the via copper "dot" and put a 0.3mm solder ball on it and try if it wants to flow onto it. Then put another ball there to create some more "flesh" and flow a really fine wire into it.
 
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