Automotive style smoke machine to detect leaks runs on a 12 V system one of the techs used battery charger to run it which burnt it up causing the red light to flash which according to the manufacture is an open circuit, I opened up the system checked the resistance on the existing wire found it was burnt replaced the wire with Nichrome 60 wire, 20 AWG, 0.6592 Ohms/ft, I used 4 ft. at about 2.1k but the red light consistently flashes, checked the diodes, caps, fets and resistors the only thing I did not check was the OP777 op amp and the PIC12F675 Flash 8-Pin 1kb 20MHz Microcontroller . If I turn on the switch and then touch the wire it heats up fine but if the wire is connected and then turn it on, it fails. With 12v supply I get 4.4v at P1, and after turning it on I get 12V. Any help would be appreciated. Also can’t find much info on Q2 (1AL markings)
Attachments
-
1.6 MB Views: 11