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DC Smoke Generator

teebee111

Aug 30, 2020
7
Joined
Aug 30, 2020
Messages
7
Automotive 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)


https://imgur.com/Zx3c6KH
 

Bluejets

Oct 5, 2014
5,994
Joined
Oct 5, 2014
Messages
5,994
Place your images here....link does not work (at least for me).
Many will not follow links to strange dodgy sites......
 

teebee111

Aug 30, 2020
7
Joined
Aug 30, 2020
Messages
7
Zx3c6KH.jpeg
 

Bluejets

Oct 5, 2014
5,994
Joined
Oct 5, 2014
Messages
5,994
Not much one can do with an apparent error signal from the uC especially without any circuit details and one could be almost 100% certain that none would be available.
Looks like a bin job if the obvious control devices are intact.
Don't know how you managed to check the electros in place but there ya go.
 

teebee111

Aug 30, 2020
7
Joined
Aug 30, 2020
Messages
7
No i removed them from the board here is a link to the data
smoke-data-pic.jpg
 
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