Circuit board help

I was given a broken hot plate, after verifying that the the cord worked, I pulled the board out of it, is there a way I can troubleshoot it and figure out what my problem is? It has less that are supposed to come on when it is turned on, they do not work.

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Well I think the Triac (black 3 wire box with the heat sink mount. Bottom right lower image bottom left top image. The conductors look oxidized, and the solder joints look bad. That device powers the heating coils and is adjusted in power by the circuit. The 4 black things near the transformer are diodes in the power supply. Teat there on 200vac setting (to be careful) if no voltage there, the transformer is bad. The transformer probably is not replaceable the Triac probably is if you can get a number. That is all I can give you from here! Jim
 

First of all, be VERY careful working with this as parts of the circuit bard are at wall socket voltage.

"Back in the day" we used "isolation transformers" when working on TV's or radios with a "hot chassis".

As to basic troubleshooting, is the fuse "good"?

Is there 120 VAC to the transformer primary?

If so, is there lesser Volts AC at the transformer's secondary terminals? (If there is I'd think an indicator light might be on?)

If 120 VAC in and nothing out, likely a "thermal fuse" tucked into the transformer windings has blow n for safety reasons pretty much rendering the unit high-tech scrap.

If you are comfortable you can do those basic checks safely post back and let us know what you find out.
 
It is working now! I resolved around the triac and it started working. I think it should be useful for some things in the shop.
 
Resolved?? Or did you resolder?? If you had the wiring diagram for it and trouble shooting for it that would be a big help. Been decades since I left such stuff behind and went to what I have always liked doing. 6 year Navy E.T. computer
 
Resoldered, stupid autocorrect keeps trying to change it to resolve. I thought where that was soldered looked suspect but it has been several years since I have tried to do anything with circuit boards. I'm not complaining though, I have an hour tops in my time and now I have a decent laboratory grade hot plate.
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If I remember right your still a kid as in under 21 right?? Back when I was your age I did a lo of repair to old TVs etc. That was before I joined the U.S. Navy in 1974 and became a Navy E.T. and repaired computers. I almost became an Ham radio operator but having to do code at 13 words a minute was not what I wanted to learn. But I still know SOS
 
I thought I had your age right/close. Back when I was your age I messed with radios and TVs a whole lot and fix them and sold them to make extra $$. But now days most things are made to be thrown away not fixed. Years ago I was given a TV that would work til it got warm then it would stop working till you hit it a few times. Got to the point hitting it did not work so I opened it up and used a solder sucker and remove all the solder from all the solder joints then solder them all back up and it works for years. Over the years I learn to hate electronics and working on things. But then again that was when we still could work on thing and I learned about and gates and Nor gates Nand gates etc. Shoot the sub I was on could have put an end to the world 2 times over
 
I've always enjoyed taking things apart, I think that is partly what led me to be interested in old farm equipment, you can put it back together without 10 grand in computers to tell you what wire goes where. I can kind of follow basic wiring diagrams, small electronics is not something I am good at.
 
I'm a whole lot older then you back back when I was your age I would take things apart and put them back together. Not always right but I would try. Back when I was about your age I picked up 2 Honda 50 motorcycles one had the automatic clutch and the other a hand clutch. I built a good running one out of the 2 but ended up with a transmission that had 1st, 2nd and 4th due to using the automatic clutch but the 4 speed clutch type transmission. I also built an electric go cart. My problem with the go cart was I didn't have an extension cord long enough to get it up to top speed. It always unplugged it self before top speed. By the way by your age I was legal to drive on the road for 2 years and was legal at the age of 14
 
I had my school permit at 14 and had learned to drive a manual before I got my permit. I never seem to find motorcycles that I can afford, earlier this year I got a cheap Chinese one out of my neighbors junk pile, got it running, had some fun then sold it and bought some tractor parts. I pay for all of my parts/tractors, except the ones I am offered for free. My first engine was a 1 cylinder Italian diesel I got when I was 7, I didn't get it back together successfully though.
 

The one cylinder diesel wasn't a Lombardini was it :)
If it was then it's no wonder you didn't get it going , I had a Silla dumper that was powered by one , seemed as if I spent more time fixing it than running it .
 
Good job! As you've discovered, many problems with electronic devices can be found just by inspection. Discolored devices, broken circuit traces and blown-up capacitors are just a few examples.

I find it interesting that your simple hot plate has a computer brain. That big IC is an MC68HC705, which is a microcontroller based on the Motorola 6800 8-bit microprocessor. A pretty simple computer, but a computer nonetheless.
 
(quoted from post at 07:15:00 01/15/21)
I find it interesting that your simple hot plate has a computer brain. That big IC is an MC68HC705, which is a microcontroller based on the Motorola 6800 8-bit microprocessor. A pretty simple computer, but a computer nonetheless.

It is a lot simpler (and probably cheaper) to design the board that way, rather than trying to implement a PID controller in hardware.
 
I was on the SSBN633 did 3 tours on it then went to the JFK. If your in Macks Creek your about 20 miles from me. I live south of Camdenton out close to the air port
 
I think it was an acme, it was on a bcs
tiller. The end of that project came when
I dumped oil all over the concrete barn
floor.
 
TractorTucker, You have an interest and the desire to learn. You are heading down the right road. And hanging out hear will help you a lot as well. Good Job!
 
My first motorcycle cost me $110.00 and it was a Honda 50 scrambler which meant it was a on/off road bike. It was also the first thing I had a license to drive. In TN at the time you could get your license at 14 if you had a motorcycle of 5 brake HP or less
 

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