Controller Troubleshooting

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Bobby_M

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Ok, my 25 year old electronics education is now failing me. Keep in mind that I was being a bit lazy in that I wired this thing as I went using what I can only figure was brazen overconfidence. After it didn't function the way I was expecting, I decided to trace everything and document what I did in this diagram. In order to not clutter the drawing, I left off the ground connections though everything is all bonded together correctly, just ignore that.

Intent... L14-30 coming in and also an L14-30R pass-through outlet. Since I often have to test other controllers, I wanted an accessible outlet since my actual outlet is a bit out of reach. That's just to explain why there would be an unswitched 4 wire outlet since it's not typical in any way.

There's also one switched 5-15R for the pump output and one that is always on for plugging my stir plate in as it will be closer to my brew station than any existing outlets.

I was trying to stay lean inside this box and therefore wanted to use the contactor as the element enable function and not use a second "main power" contactor. I used a NO key switch to interrupt the whole low current supply including power to the DSPR itself, the line side of both the pump switch and the element enable switch that finally feeds the contactor coil.

Now, on to the strange behavior. With the key switch off, pressing either the element enable or pump button will cause the DSPR to light up as well as the green "panel on" LED. Note that the contactor will not close with the key switch off.

With the key switch on and the pump switch off, I get 80 volts at the pump outlet. With the pump switch on I get 120v. The problem there is that the LED on that switch lights dim or bright, never off. Also since I'm using the Topsflo pump, the 120v to 24VDC pack puts out 24v in both states so I can't turn the pump off.

I was hoping I would immediately see the problem once I had it drawn out but I'm not seeing it. I need some fresh eyes on it please.

The contactor coil is rated at 120v. The blue and orange push button switches have NO contacts only and the built in LED is rated at 240v.

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RiverCityBrewer

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I assume your 80v measurement is between the hot and neutral, what does it read between hot and ground? I also don't understand the connections to your pushbutton switches, why are there two hot legs running to them? Maybe a link to the pushbutton switch would give me a better understanding of the terminals. I'm guessing its a 240v switch, so you may also be getting trickle through voltage from the pushbutton lights that show as voltage with a digital multimeter, but if you connect an analog meter to it, it will show 0v.
 
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doug293cz

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...

Now, on to the strange behavior. With the key switch off, pressing either the element enable or pump button will cause the DSPR to light up as well as the green "panel on" LED. Note that the contactor will not close with the key switch off.

...
If you unplug the pump 120VAC to 24VDC supply from the pump outlet, so the behavior above change so that the DSPR and green LED only come on when the when the element enable switch is turned on, but not when the pump switch is turned on?

Brew on :mug:
 

501irishred

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By disconnecting L2 from the pump push button, you could prove or rule out trickle voltage from the indicator light. If it corrects the problem (minus not having a pump on indicator), the easiest fix would be to change your push button with one that has a 120V indicator.
 

ITV

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I suspect that the problem is leakage current through the LED lights.
I am a bit rusty with LED lights but adding a series resisitor (2.5 - 5K ohm?) may correct the problem.

Link
 
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Bobby_M

Bobby_M

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I assume your 80v measurement is between the hot and neutral, what does it read between hot and ground? I also don't understand the connections to your pushbutton switches, why are there two hot legs running to them? Maybe a link to the pushbutton switch would give me a better understanding of the terminals. I'm guessing its a 240v switch, so you may also be getting trickle through voltage from the pushbutton lights that show as voltage with a digital multimeter, but if you connect an analog meter to it, it will show 0v.

They are pushbuttons with built in 240v LEDs. Those LEDs use that center colored block and are independent from the state of the NO contacts (which are on the sides of the LED block). That's why there's a L1 loop connecting the switched side of the NO into one of the LED contacts. L2 is connected on the other side so they light when the switch is on.
 
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Bobby_M

Bobby_M

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By disconnecting L2 from the pump push button, you could prove or rule out trickle voltage from the indicator light. If it corrects the problem (minus not having a pump on indicator), the easiest fix would be to change your push button with one that has a 120V indicator.

Yeah that sounds like a good first step. I'll try that tomorrow when I get back to the shop.
If you unplug the pump 120VAC to 24VDC supply from the pump outlet, so the behavior above change so that the DSPR and green LED only come on when the when the element enable switch is turned on, but not when the pump switch is turned on?

Brew on :mug:

I will try this. One thing I didn't explain clearly is that I have also hard wired the 24vdc power pack inside the enclosure so I have to unclip the fork terminals
 

doug293cz

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Yeah that sounds like a good first step. I'll try that tomorrow when I get back to the shop.


I will try this. One thing I didn't explain clearly is that I have also hard wired the 24vdc power pack inside the enclosure so I have to unclip the fork terminals
The reason I asked, is there is a path to neutral from the green light thru the element contactor when the contactor switch is closed, but that doesn't exist when only the pump switched is closed. Disconnecting the pump power supply would verify whether or not there is also a return current path thru the pump power supply.

I'll continue studying the drawing to see if I can explain any of the other odd behaviors you see.

One thing that would probably help is to use a double pole key switch that disconnects both hot lines when off.

Brew on :mug:
 
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Bobby_M

Bobby_M

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The reason I asked, is there is a path to neutral from the green light thru the element contactor when the contactor switch is closed, but that doesn't exist when only the pump switched is closed. Disconnecting the pump power supply would verify whether or not there is also a return current path thru the pump power supply.

I'll continue studying the drawing to see if I can explain any of the other odd behaviors you see.

One thing that would probably help is to use a double pole key switch that disconnects both hot lines when off.

Brew on :mug:

I'll also document various phenomena with various button presses and voltage measurements.

I'll try sequentially removing the LEDs one at a time to see if any one particular is the problem.
 

itsnotrequired

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I assume your 80v measurement is between the hot and neutral, what does it read between hot and ground?

this is the key question. if 80v between hot and neutral yet 120v between hot and ground, you have a loose/disconnected neutral. if 80v between hot and both neutral/ground, you got a hot conductor issue somewhere (or a bad source circuit breaker).
 

ITV

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They are pushbuttons with built in 240v LEDs. Those LEDs use that center colored block and are independent from the state of the NO contacts (which are on the sides of the LED block). That's why there's a L1 loop connecting the switched side of the NO into one of the LED contacts. L2 is connected on the other side so they light when the switch is on.
The 240V LED lights that I am familiar with are intended for the European market, they have 240V on one leg and a neutral on the second leg unlike the US where we have (2) separate 120V legs to get 220V. In your circuit there is no neutral for the LED lights.
 

doug293cz

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The 240V LED lights that I am familiar with are intended for the European market, they have 240V on one leg and a neutral on the second leg unlike the US where we have (2) separate 120V legs to get 220V. In your circuit there is no neutral for the LED lights.
As far as the LED is concerned, 240/neutral or +120/-120 matters not a whit. It's all about the voltage potential across the device terminals.

Brew on :mug:
 

ITV

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As far as the LED is concerned, 240/neutral or +120/-120 matters not a whit. It's all about the voltage potential across the device terminals.

Brew on :mug:
I agree as far as measuring voltages. I'm suggesting that with LED lights there could be leakage causing the 80V scenario.
 

RufusBrewer

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It is easy to get tricked by using a digital multimeter. Digital multimeter have a high input impedance. You can measure a high voltage but it at next to nothing current and is a voltage reading that could be a red hearing.

If you are measuring a voltage source that has passed through a solid state device, you might be measuring the leak voltage.

To be honest, I could not follow OP to be sure if this is a solution to your situation. But it is worth mentioning
 
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Bobby_M

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I spent some time with it and jotted down all kinds of notes that only 2 hours later I can't really make any sense of.

The first thing I tried is disconnecting all the indicator LEDs to see if anything functionally changed. I also removed the AC/DC powerpack off of the pump outlet.
Pump output voltage was zero with key and pump sw off. Pump voltage went up to 119v when key off but pump sw on. Voltage went to 124v when key and pump sw on.

I also tried removing the neutral wire from the 120v contactor coil also with the pump AC/DC pack removed (LED indicators all connected as shown). Everything seemed to work fine with the exception of the contactor not closing because the neutral is disconnected. I do not recall if I tested the pump outlet voltage in various states but nothing was lighting unexpectedly when any buttons were pressed.

Coil neutral still disconnected, pump 24vdc pack reconnected: Blue indicator always dimly on regardless of all switch positions. With key sw off, the pump outlet reads 19 to 39VAC. Pump switch on makes both the blue and green LED flash on and off. Voltage on pump output tracks with the flashes flopping between 60-70 VAC. WIth the key switch on and the pump switch on, it reads 124V.

I neglected to repeat these tests with an actual load on the element output to eliminate leakage current through the SSR but in past builds, this has only impacted the LED parallel to the element output. I also want to try it with the pump actually connected to the powerpack.
 

itsnotrequired

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the L2 running off the pass-through receptacle, over to the switches, any reason not to move that L2 to the neutral? i'm not seeing the advantage in having that hot. i guess with them being rated 240v the led may be dimmer.
 
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Bobby_M

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Following up with the results after sporadically troubleshooting. Ultimately I couldn't stop the 80 volts showing up on the pump outlet (with the key switch and pump switch off) and it was definitely leaking through the indicator LED on the pump switch. I tried putting a load on there like a 120v 75watt light bulb and all it did was light up the DSPR320 and "panel on" LED even with the key switch off.

The easiest solution I could come up with is to add a N.O. contact to the pump switch and I'm running the L2 through that contact before it hits the LED terminal. In other words, the LED has no connection to anything unless the button is pressed. Now everything works as designed.
 
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