Could My SSR Be Bad?

Hello all,
I recently posted a different thread that conviced me to buy a new PID. I picked a MyPIN TD4. Previous Thread

My current issue is that I am trying to tune the PID. After I hit the setpoint, the temperature just keeps rising. I am using a Fotek 40A SSR.

Is there some troubleshooting that I can be doing? I don't quite know why it would continue to heat even with the PID output off, SSR indicator light off. The schematic hasn't changed much with the exception of the PID model and I added some contactors to turn things off without arcing the electricity when I unplug it.

If both the PID and SSR indicator lights are off, but the SSR is still passing power... yup sure sounds like it's failed closed. Sadly too common of an occurrence with those Foteks.

Can you post a wiring diagram we can double check?

iijakii said:

If both the PID and SSR indicator lights are off, but the SSR is still passing power... yup sure sounds like it's failed closed. Sadly too common of an occurrence with those Foteks.

Can you post a wiring diagram we can double check?

Click to expand...

Previous Wiring Diagram. Note the changes in my OP on current thread.

This is a common failure mode for SSRs. They fail ON. Put a voltmeter across the output terminals. If the little light is out and there is only a fraction of a volt across those terminals (system energized) then it is still conducting even though it is not gated. Or use a clamp-on ammeter.

ajdelange said:

This is a common failure mode for SSRs. They fail ON. Put a voltmeter across the output terminals. If the little light is out and there is only a fraction of a volt across those terminals (system energized) then it is still conducting even though it is not gated. Or use a clamp-on ammeter.

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With the light on, I am reading 1.44v. With the light off I'm still reading 1.4v. Any recommendations on a higher quality SSR?

Auber has 'em in the US if you want something quick / tech support and what not. On eBay you can search for "Mager MGR-1 D4840" and it's the same item as they sell, cheaper but shipping time for China. Lots of other higher-end brands like Crydom etc if you want to spend some significant coin.

foy1der said:

With the light on, I am reading 1.44v. With the light off I'm still reading 1.4v. Any recommendations on a higher quality SSR?

Click to expand...

Yep, your SSR is toast. @iijakii gave you a good pointer for replacement.

Brew on

OK, I ordered the one from Auber. There is a small realization here though. If this is the "good" SSR, and the bad one is $5 less, who the hell would pay for the **** one? If I knew that high quality stuff could be had for that price, I would have gone that way first. But honestly, I'm an amazon junkie: "What do I need? Is it on Amazon? Yes? DONE" This might need to be shouted from the mountaintops.

Thanks for the advice.

foy1der said:

OK, I ordered the one from Auber. There is a small realization here though. If this is the "good" SSR, and the bad one is $5 less, who the hell would pay for the **** one? If I knew that high quality stuff could be had for that price, I would have gone that way first. But honestly, I'm an amazon junkie: "What do I need? Is it on Amazon? Yes? DONE" This might need to be shouted from the mountaintops.

Thanks for the advice.

Click to expand...

Yeah I didn't know about the Magers either when I ordered some Foteks. At the time it was twice the price for the Aubers vs them, so I risked it. Especially when you could find Mypin TD4/Fotek combos for even cheaper. Not worth going for the Foteks anymore in the slightest. Hope your issues are resolved with that.

I was wondering about your diagram though. It shows the PID feeding to a 24v power supply which was powering the SSR? Was that for your old PID? The new one you have sends a 24v signal, so you don't need that.

YES! I forgot to mention that I pulled the 24v psu when I got the new PID. Sorry about the confusion. It's a much more simple panel now.

If you are patient, you can buy quality SSRs (crydom, omega, etc) on ebay for nearly the same price as these cheap models. You would probably be better off buying a used crydom than a new fotec.