Okay here:
U107 4-8 = 28,6VDC
4: -14,18 and 8: 14,26
I did some mistake earlier.
U108
7 - 14 = 0,00
Driver ic pin11 = 0,17VDC (black probe negative rail)
U107 4-8 = 28,6VDC
4: -14,18 and 8: 14,26
I did some mistake earlier.
U108
7 - 14 = 0,00
Driver ic pin11 = 0,17VDC (black probe negative rail)
Can you find what's supplying 12v (above the negative rail) to U108 and the driver IC?
Could it be Q12?
Have you replaced the burned resistor near Q12?
Could it be Q12?
Have you replaced the burned resistor near Q12?
Okay the original Q12 broke when I took it off the board. I don't have a new exact that kind of transistor so I replaced it with some other transistor wich had a collector current value high enough. I don't know if it works like it should but now there is only 2,1VDC between pins 7 and 14 on U108.
It seems like the Q12 is supplying 12V to U108 and driver IC, there is only 3kohm resistance between Q12 emitter and U108 pin 14.
Tested to take Q12 emitter leg out of board and there is 12,68VDC output. And if I solder it back to board the voltage drops to 2,1volts and is heating. The burned 10ohm resistor reads still 10ohms.
So into my eyes it seems like something after Q12 is drawing current and pulling voltage down. Also I may be all lost here too 😀
It seems like the Q12 is supplying 12V to U108 and driver IC, there is only 3kohm resistance between Q12 emitter and U108 pin 14.
Tested to take Q12 emitter leg out of board and there is 12,68VDC output. And if I solder it back to board the voltage drops to 2,1volts and is heating. The burned 10ohm resistor reads still 10ohms.
So into my eyes it seems like something after Q12 is drawing current and pulling voltage down. Also I may be all lost here too 😀
I wouldn't expect any significant resistance between the U108 p14 and its source of power. 3k is far too much.
Won't seem to find anywhere less than 2kohm resistance.
E: I've asked GZ for schematics so if I will get those maybe this will open up a bit.
E: I've asked GZ for schematics so if I will get those maybe this will open up a bit.
U2 is the one supplying U108, looks like it is voltage regulator 7805. Pins 2 and 3 measure short
I think not because it is on the other side of that 7805 but I'll measure when I get back home
E: 1,9Mohm
E: 1,9Mohm
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