Paragon A-88B wiring challenges

[PotteryEnabler]

Hello,

We got an old A-88B kiln from a friend and after a bit of cleaning, it fired right up. On the first try, we ran a bisque firing to cone 05 and a glaze firing to cone 6 successfully! An element broke sometime in the first firing so we replaced that. On our second bisque firing it seemed to be heating up alright (made it to about 350) but then sputtered out a couple of hours into the firing. It only functioned on High setting after that to any appreciable degree. Only the first and third elements out of four are turning red despite being on High.  All elements are intact. Full power coming through the two hot lines all the way to the control box. Neutral and ground intact.

Aha! A wiring problem, I thought. But after triple checking our wiring with the old diagram and even switching a few things around, we could not get more than two elements firing. Still seems like this is a series/parallel switching issue, right?

Aha! A switch problem, I thought. Maybe? After taking apart the 4 way rotary switch, it did seem to barely/not reliably making all the connection changes. The plastic hub inside was quite worn down with very little throw. I did a little dremel work to increase the high:low ratio on the hub and after some careful bending of arms, I have the switch reliably switching again (or at least repaired from any damage I may have caused!)

I thought before I wire up and screw everything together for the third time, I might check for additional sage wisdom on repairing these. I'm on a crunch to not dissappoint my son and wife who are hoping to fire in just a couple days to make a weekend opportunity for their first sales.

Any advice is much appreciated for on things to check, to recheck, and common mistakes that I probably made! Thank you

[Bill Kielb]

This kiln requires a traditional 4 wire 240v circuit so first question do you have: L1,L2, Nuetral, Ground wires? If you don’t, it will not work. (Drawing below)

An addition here would be elements wear together and get replaced together. Worn elements that burn open are usuallly extremely brittle so I would be curious what the remaining elements measure resistance wise.

Edited November 28, 2023 by Bill Kielb

[PeterH]

Something to keep at the back of your mind.

IF the 4-way switches need replacing

OR you don't have a 4-wire 240v circuit (L1,L2, Neutral, Ground wires)

... you can change to using infinite switches ( which also gives you finer temperature control)

As (in some cases) recommended by the experts, and apparently Paragon (who seem to no longer stock 4-way switches).

... and  Paragon don't seem to sell replacement 4-way switches anymore
https://paragonweb.com/product-category/parts/switches/

... remembering that a generic infinite switch from a high-volume supplier may be cheaper than one from Paragon.

Edited November 28, 2023 by PeterH

[PotteryEnabler]

Thanks for the replies! I recognize both your names from other posts with similar problems I've been scouring for the past day and owe credit to you both for some testing I've done so far.

Yes, I have a 4-wire 240v. It's wired up to a 4 prong twist-loc so I can use the same plug for welders, etc. I get full power all the way to the control box in the kiln.

Element wear and differences in resistance: they all measure around 9.4-9.8 Ohms, both new and old.   That seems close enough to not matter? Maybe the one that broke was the oldest of the old ones?

I looked into the infinite switch idea, as well, but if I can avoid dropping $100-150 to swap them, I will work hard to do it. Plus that's even more rewiring to test. I'm hoping the dremel facelift to the internal hub will fix that.

I have peered closely at that wiring diagram and wished for higher resolution a lot the past few days. I suspect the kiln was wired slightly differently than the diagram originally. I'm guessing that it was a difference in how they wired it to get a single element on the bottom rather than the middle to be On element during a Medium fire.  With the way the diagram is, I think the bottom elements ( 2& 4) are the ones firing with the medium switch, is that correct? That's also why it is so confusing that my elements 1 & 3 came on only when following that diagram.

 

[PeterH]

9 hours ago, PotteryEnabler said:

Only the first and third elements out of four are turning red despite being on High.  All elements are intact. Full power coming through the two hot lines all the way to the control box. Neutral and ground intact.

It looks to me like the top element (in the diagram, not necessarily in the kiln) is only fed by one of the 120v lines (the upper one in the stylised plug/socket). Although you say that both 120v lines are getting to the controller, is the upper one also getting to the switches and/or elements?

PS

>I have peered closely at that wiring diagram and wished for higher resolution a lot the past few days

For a different kiln, but probably/possibly the same circuit
https://content.invisioncic.com/r278179/monthly_2021_11/AFFD763E-B04E-4A36-A21B-049717307DB1.jpeg.d8d19f63656d62487cfde60f695535d2.jpeg

... asking for coloured felt-tips on the different styles of dashed lines

Edited November 28, 2023 by PeterH

[PotteryEnabler]

Thanks for that diagram, much easier to see!

Good question about power getting to both switches. Yes to the bottom one for sure, but I have the top one out and will re-assemble this afternoon after replacing some connectors. An arc flash from a bouncy stray lead would indicate power is good.

That's what is so frustrating about the process here, is that I see the diagram, understand the flow, it looks like it should work, tests out ok (in my limited ability to know how to test circuits)...but doesn't work. 

[Bill Kielb]

If this helps - The only situation where a single element of the pair runs on 120v appears to be the medium setting. Here is the location of the full diagram from the Paragon website. This kiln has a diagram for the quick connect switches as well. Quality still not the greatest.

https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/A82WD.pdf

[PeterH]

10 hours ago, PotteryEnabler said:

I suspect the kiln was wired slightly differently than the diagram originally. I'm guessing that it was a difference in how they wired it to get a single element on the bottom rather than the middle to be On element during a Medium fire.  With the way the diagram is, I think the bottom elements ( 2& 4) are the ones firing with the medium switch, is that correct? That's also why it is so confusing that my elements 1 & 3 came on only when following that diagram.

 

9 hours ago, PotteryEnabler said:

That's what is so frustrating about the process here, is that I see the diagram, understand the flow, it looks like it should work, tests out ok (in my limited ability to know how to test circuits)...but doesn't work. 

Idle thoughts ... sometimes you can error-guess, sometimes you need more data

What tests have you been doing, and are they on the powered or unpowered kiln? Do you have a multimeter?

Lets assume that the wiring corresponds to the diagram, and the components work.

With the kiln unplugged and the meter measuring resistance you should be able to test for continuity ("zero" resistance) between the L1,Ll2 or neutral at the plug and the ends of the elements. Repeat with the 4-way switches in each position.

So with one switch off there are  12 measurements for each position of the active switch.
(L1,L2, neutral)x(both ends of top element, both ends of bottom element) = 3x4 = 12
... if, as looks likely, the "middle" ends of pairs of elements are physically connected (e.g. go into the same switch connector) this reduces to 3x3 = 9.

Basically demonstrating the the connections shown in red are there, and no other connections  exist from an element end to the plug's L1, L2 & neutral.

If some connections aren't there, trace them from L1/L2/neutral through the wiring, and see where connectivity is lost.  

If spurious connections exist, think about it.

PS Two wiring diagrams for the A88B at https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/A82WD.pdf

One for push-on terminals and the other for screw-on terminals.

It also has a legend converting the b&w line-type to wire colour. I'd be inclined to colour-in a copy.

Edited November 29, 2023 by PeterH

[PotteryEnabler]

Well, I put it all back together carefully this afternoon. After attempting some of PeterH's solid multimeter testing advice but becoming more confused the more things beeped at me, I gave up and just fired it up.

It VERKS! It fired up and the correct elements turned on and got orange.  I actually have no idea what the magic sauce was in rewiring or grinding down that switch hub. We'll see if it lasts through a glaze firing tomorrow. I will admit the brand new element gets a little hotter faster, but they all got there. Resistance is close to the same on all of them, so I don't think I'll replace them all. 

Thank you all for your help and I'll wager that this is not my last time with a pottery related problem. My wife and son have taken up pottery as a hobby, and I have apparently taken up electrical engineering, induction motor repair, refractory masonry and material science along with various other brain growth activities to keep them at it.

As payment for your assistance, I colorized the wiring diagram for us all. 

[neilestrick]

24 minutes ago, PotteryEnabler said:

It VERKS!

Congrats! If one of the switches goes out again, replace them with 240V infinite switches with the element pairs wired in series. Better control, simpler wiring. Have fun!

[PeterH]

Congratulations. Fingers crossed.

Presumably you improved some connections and/or the last switch you examined?

But there are two pretty independent sets of (switch + element-pair), and some thing(s) have affected both of them.

Maybe where two wires shared the same switch terminal (presumably on the switch you have just re-connected)?

PS Reminds me of my software days.
Heisenbug https://en.wikipedia.org/wiki/Heisenbug
In computer programming jargon, a heisenbug is a software bug that seems to disappear or alter its behavior when one attempts to study it.

Edited November 29, 2023 by PeterH

[PotteryEnabler]

Fired up great and in record time to hit cone 6. 

Yes, clearly I flushed out the electronics gremlins and Heisenbugs. I'm going to say it was the switch, since that was my most clever, daring, and skilled work. That or my wife was correct and I just managed to "turn it off and on again" enough times.