reverse engineering help

[atntias]

Hi,
I have a circuit meant to control AC solenoids, and using TRIACS to do so, and I'm trying to externally control it.
Its seemed fairly simple so I started measure voltage and make sens of the board, and as soon as i connected a scope the whole thing blew up , So...I got a replacement board and made a full schematics of it.

It uses an atmega8, I might be able to reprogram it to my purpose or replace it with an arduino chip, either way the impotent part is to understand how the triacs control the coils, and how not to blow the board agian.

the board takes a 220V input, and controls 4 coils, the board allows intensity and rhythm control, my guess so far is that an pulse at the base of the 2222a somehow determines the amplitude of the ac voltage and 0 is off... not sure..
but before i try to poke the board again id appreciate any advice, and some DO's And DONT's for the board.

here is a the eagle schematic View attachment MAESTRO.zip all the values and part numbers are accurate. U3 is just a low voltage detector, TH1 looks lke a cap but behaves like a short, not sure what it is.., R999 is a fix to the board that looks like it was done manually after manfuactering, feel free to ak any question, verfy anything, request tests or mesures...

attached some pics








thanks! atntias

 

[ZASto]

Your "whole thing blew up" because you have no isolation from mains.
Use a 1:1 transformer or for your scope or for "the thing that blew up".

 

[wizpic]

My guess would be if the circuit blew up then the scope may have been damaged see here
https://www.eevblog.com/2012/05/18/eevblog-279-how-not-to-blow-up-your-oscilloscope/

 

[Venkadesh_M]

I think isolation is the issue where did you gave the neutral??