PID wiring help

[VHoward]

I have an RCBS Promelt pot that works pretty good. I bought stuff off of evilbay to put together a pid temp control box. A Mypin TA04 PID, a 25A SSR and a K-type temp probe.

I followed the simplified schematic found in this thread : http://castboolits.gunloads.com/show...ol-temperature in post #10. The pot never turns on. The PID turns on, goes through it's start up procedure and then it reads the temp the pot it at. But never supplies power to the pot. I have been through the settings on the PID to make sure it was set for farenheit and that it was set to control a SSR.

Any ideas appreciated.

Thanks Vance

[VHoward]

Never mind. I figured it out. Had a wire going from the SSR to the pot hooked up wrong. It is working now.

[VHoward]

OK. A different problem now. The PID does not turn the pot off when the temperature is reached. I turned the auto-tune feature on so it would learn the pot, but it doesn't have any effect. My pot just goes all the way up to the pot maximum temp.
I wonder if I got a defective SSR or PID?

[Frozone]

Do you have a VOM (volt ohm Meter) handy?

Disconnect the PID from the SSR - does the pot still heat?
If so your SSR is bad.

BTW if you hook up a lamp to the thing instead of the pot for testing, it works pretty well.

OH and just which model TA4 did you get? ta4-srn?

[w0fms]

Second what Frozone said also. If the SSR "blew" it often will blow "on". I use a 40A SSR on mine, but it's overkill in many cases. When the MyPin TA04 (which oddly enough is the same e-bay "special") I have on my hotplate (I use a hotplate and a cheap "sauce pan" for my casting pot) is tuned you will get very short bursts of on/off. But the lamp is a great idea.. you can even temporarily attach the k-thermocouple to the surface of the lamp and have it use that as a heater.

I assume your k-thermocouple is reading the correct degrees F on the display as it is heating? I had to electrically isolate my thermocouple from my hotplate because of the grounding situation of the plate ... the thermocouple looked like it was reading backwards because of that...

[HATCH]

40 amp ssr is over kill.
My master cast automated with PID control pull 8.6 amps at 240 so that would be just 17 amps at 120

[VHoward]

Do you have a VOM (volt ohm Meter) handy?

Disconnect the PID from the SSR - does the pot still heat?
If so your SSR is bad.

BTW if you hook up a lamp to the thing instead of the pot for testing, it works pretty well.

OH and just which model TA4 did you get? ta4-srn?

From what you stated, it sounds like a bad ssr. The light on the front of the pid that indicates that the ssr has been turned on or off lights when the temp is too low and goes out when the temp is too high. The Pro Melt remains on when the pid turns off the ssr. I only saw TA04 on the front of the ssr. I will look on the diagram on the side of it to see if it elaborates which TA04 I have. I only paid like $10 for the ssr with a heat sink shipped from china. Won't be worth the shipping cost to send it back.

[VHoward]

Second what Frozone said also. If the SSR "blew" it often will blow "on". I use a 40A SSR on mine, but it's overkill in many cases. When the MyPin TA04 (which oddly enough is the same e-bay "special") I have on my hotplate (I use a hotplate and a cheap "sauce pan" for my casting pot) is tuned you will get very short bursts of on/off. But the lamp is a great idea.. you can even temporarily attach the k-thermocouple to the surface of the lamp and have it use that as a heater.

I assume your k-thermocouple is reading the correct degrees F on the display as it is heating? I had to electrically isolate my thermocouple from my hotplate because of the grounding situation of the plate ... the thermocouple looked like it was reading backwards because of that...

It reads very close to what the lead thermometer says that I have (a Lyman I believe).

[VHoward]

Well, it's not a problem with the ssr. I disconnected it from the pid and the pot will not come on. The pid is a TA4-snr.

[Frozone]

Well, that light is only half the equation.
That is simply a signal that the output Should be active, not that it is actually sending a signal.
Kinda like the fuel gauge saying you have gas in the tank, but the fuel pump not working.

The SSR output on the Mypin is 'unlimited'.
It will provide as much current as the power supply can deliver ~ 80mA @ 24 V.

On Some SSRs this is more than they can handle.
Most SSRs works fine with 15 - 20 mA as signal input.
It is a Good Idea to add a resistor of ~ 1.5K Ω in the SSR signal line.


<edit>

Sounds like you blew the output circuit on the TA4.


</edit>

From what you stated, it sounds like a bad ssr. The light on the front of the pid that indicates that the ssr has been turned on or off lights when the temp is too low and goes out when the temp is too high. The Pro Melt remains on when the pid turns off the ssr. I only saw TA04 on the front of the ssr. I will look on the diagram on the side of it to see if it elaborates which TA04 I have. I only paid like $10 for the ssr with a heat sink shipped from china. Won't be worth the shipping cost to send it back.

[VHoward]

Well, I shorted the input terminals on the ssr and the pot did not turn off. The ssr says it can handle 25 volts input.

[Frozone]

Well, I shorted the input terminals on the ssr and the pot did not turn off. The ssr says it can handle 25 volts input.

WAIT,


You shorted the 2 DC control inputs together on the SSR and the pot was ON? SSR is bad.

And when the PID is disconnected the pot is OFF????

This does not make sense.


Disconnect PID from SSR.
Set the temp low so the PID is constantly off.
Measure voltage across PID terminals 4 (+) and 3 (-) it should read 0 volts.
Now set the temp high PID should be ON constantly. Same test should show ~24 volts.

[VHoward]

That is what is happening.

[Frozone]

Lets be specific, What is happening.

[VHoward]

The pid has no control over the ssr. When it is all hooked up, the pot comes on and heats up. When the pot gets to and passes the set temperature, it does not turn off. I disconnected the pid from the ssr and the pot turns off. Hook the pid back up to the ssr. When I shorted the input terminals of the ssr, the pot does not turn off.

I have ordered another pid and ssr and will try again. I have contacted the vendor that I purchased the pid from on ebay to see if they will do anything.

[VHoward]

OK. I got out my volt/ohm meter and measured the volts being supplied to the ssr by the pid. It reads 24 volts while the led indicator on the front panel is on saying the ssr is activated. When the pot reaches the set temp, that led goes out, but the pot does not turn off and the volts being supplied to the ssr is still 24 volts. The vendor says it should be 1 volt or less when the pid deactivates the ssr.

[VHoward]

The ebay vendor is also sending me a replacement.

[VHoward]

The new pid and ssr from Amazon are working just fine. Got them today. Got the replacement pid from the ebay vendor yesterday. hopefully it is good as I might have a project for it later on.

[Frozone]

Glad you got it running.

Does it bother no one else that you blew the PID up yourself with your wiring mistake, then wanted a 'Free' one to make up for your mistake.

Now the seller is out 2 PIDs for the price of 1 - and I assure you he isn't making Much on each sale.
Even in Quantity the TA4 is around $20.

The worst part is, you seem proud of screwing him.

[VHoward]

There was no blown pid as a result of any wiring mistake that I made. The pid was defective as received. So it is OK for vendors to sell you something that does not work, but not OK to ask that they replace the defective item. This was not the first pid project I built. The first one worked first time. Apparently it is OK to call people a thief on this forum for asking vendors to replace defective items.