820-2850 short PPBUS_G3H

Bohmmen

New member
This board has green light

0 volt on fuse F7040
Diode mode on fuse 0.083

When I Remove F7040 I get PPBUS_G3H at pin 1 of F7040 so short is after fuse

What should I try first?
 

dukefawks

Administrator
Check for a short from PPBUS to any of the coils to rule out a shorted high side FET. After that you can inject a few volt to see what heats up.
 

Bohmmen

New member
I'm not really sure what coils I should check. Is it F7415 and F7425? And how to check short.
I tried to remove F7025, diode mode on fuse changed from 0,083 to 0,144
 

larossmann

Administrator
Staff member
Other coils means the coil at the end of PP5V_S3, PP3V3_S5, etc. Other power lines that are derived from PPBUS_G3H. In terms of how to check a short, multimeter, continuity mode.
 

Bohmmen

New member
I wrote wrong letters in previous post

When I remove L7025 diode mode on fuse F7040 changed from 0,083 to 0,144


Resistance to groud
L7630 21 ohm (PPCPUVTT_S0_REG_R)
L7330 3.5 K (PPDDR_S3_REG_R
L7530 79 ohm (PPVCORE_S0_GFX_REG_R)
L8920 7 ohm (PPVCORE_GPU_REG_R)
L7220 23 K (PP5V_S3)
L7260 5.7 K (PP3V3_S5)
L7425 57 ohm (PPVCORE_S0_CPU)
L7415 58 ohm (PPVCORE_S0_CPU)
 

larossmann

Administrator
Staff member
what duke was asking was resistance of PPBUS_G3H to those coils of those power supplies. If there is no low resistance from PPBUS_G3H to those coils, put 1 volt in with a DC power supply on PPBUS_G3H and slowly raise it until something gets warm.
 

Bohmmen

New member
Resistance to PPBUS_G3H

L7630 52 ohm (PPCPUVTT_S0_REG_R)
L7330 6 M (PPDDR_S3_REG_R
L7530 114 ohm (PPVCORE_S0_GFX_REG_R)
L8920 67 ohm (PPVCORE_GPU_REG_R)
L7220 4.6 K (PP5V_S3)
L7260 0.83 K (PP3V3_S5)
 

Bohmmen

New member
Ok. I don't have a lab power supply. Looked at the old video with Louis where he uses a atx power supply and the led strips in the window. Started with 5 v, nothing. Tried 12 volt and still nothing burning. Checked with my fingers and with alcohol. Am I doing something wrong?
 

Bohmmen

New member
Resistance to ground on ppbus is 67 ohm. I don't have F7040 soldered back yet so I'm messuring after the fuse.
I belive everything is ok before the fuse.
 

dukefawks

Administrator
67 is a bit high so there will not be a lot of heat generated. Make sure to use a power supply that doesn't shut down when connected. Use your lips to feel the board
 
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