Need a little electromics help

I'm not seeing much in the way of "smarts" on that board. Looking at the component side, the 3-terminal package just below the two caps on the upper right side of the board is a +12V voltage regulator (center pin is ground, bottom pin is the output). The larger rectangle halfway down on the left side of the board looks like a relay. I see what's probably a triac on the lower right side, and (perhaps) another relay near the bottom-center of the board.

I don't see anything that looks like a micro-controller. Maybe you're missing a board?
 
Hellow , very helpful :)

green = -ve low voltage
yellow = +ve low voltage
orange = PWM input
Red = Relay input (connect to +ve low voltage to engage, interlock conection I think)
Brown = Not conected ? I cant see a trace on the picture.


I did a little sketch , I might have traced something incorrectly if anyone sees an error, (I missed some of the details off, its a bit simplified)

circuitSketch-basic-1.jpg


Stu


You aren't kidding!

The red wire from the connector looks like it controls the relay. The tan wire looks like it has no connection, but that white paint makes it impossible see for sure.

This may help, I mirrored the image of the bottom of the board and placed it next to the top. Maybe a fresh set of eyes can spot something else:


View attachment 304360
 
Ive traced the 5 pin connevtor to the major components
Brown is unused

Green goes to + of both large caps and the left leg of the voltage regulator.

Yellow goes to - of both large caps and the middle leg of the voltage regulator.

Red goes to the relay and is connected to the right leg of the voltage regulator via a resistor.

So am i correct in assuming green and yellow fed power to another board that selected stitch styles etc and returned a PWM signal via the orange wire?
 
Ive traced the 5 pin connevtor to the major components
Brown is unused

Green goes to + of both large caps and the left leg of the voltage regulator.

Yellow goes to - of both large caps and the middle leg of the voltage regulator.

Red goes to the relay and is connected to the right leg of the voltage regulator via a resistor.

So am i correct in assuming green and yellow fed power to another board that selected stitch styles etc and returned a PWM signal via the orange wire?

The PWM exactly as you say , the relay should connect directly to the supply (mostly) their should be a voltage rating on the relay itself , (sorry for polarity mix up ;) )

You could use a simple Arduino example program to drive pwm from a variable resistor and as you say wire the relay to engage it.

Stu
 
Thanks Stu
So i can do away with the low power section of the board, replace the relay with a switch and feed PWM to the opto isolator? Starting to sound doable for my limited electronics knowledge.
 
Thanks Stu
So i can do away with the low power section of the board, replace the relay with a switch and feed PWM to the opto isolator? Starting to sound doable for my limited electronics knowledge.


Yeah just wire to the jumpers on the low voltage side with a new pwm system , a switch on the relay might enable you to keep the pwm program very simple.

one question i see is where is the red and brown wire going ? they look to be in the circuit that powers the relay , is their another switch they run to ?

Stu
 
That board looks like it has a lot of smoke built up inside of it, be careful not to let it out ;)
 
Just be careful while putting your system together! There's 120VDC present, with not much to prevent substantial current flow through various body parts.
 
It looks to me that the brown and red wires are connected together. 2 different switches that either one can turn on the relay.
 
I've heard of design by committee, but so far not debug by committee. This is a personal first.
 
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