Need Electrical Engineering help
 

So I guess I celebrated a little too early having the silkscreen dryer hooked up. I hope someone here can help troubleshoot this enough to I know what to order/replace.

The dryer works with 3 unique heating elements suspended over the conveyor belt. After getting it working, I found:

1. one heater worked close to or at spec (13 ohms)
2. one heater worked half as well (26 ohms)
3. one heater did (no continuity)

I took the heater that did not work, opened up the sheetmetal, dug down through the clay wadding and found the 2 leads were rusted away. I welded new metal contacts to the coils (very difficult), took the heating element board, laid it on top of the another (sheetmetal box), hooked it up and it worked, and worked great! Put it back in its sheetmetal box and laid that box back in the frame, didn't bother to bolt it in.

I took the half-efficiency heater and pretty much did the same thing. Went back, wired it up, and...

NONE of them work.

here's where I am at.

All three have continuity at 13 ohms across the two contacts

All three have 120V going to each lead

All three are stone cold


What am I missing? How can they not heat up if each lead/contact has 120V going to it and each has good continuity?

There is a temp controller that could be bad, but I don't understand how e- can be going to the heaters but they don't heat up. Do the sheetmetal boxes need to be bolted to the frame essentially grounding them?

The wiring diagram is basic. 230 comes in and goes to a mercury contactor. Temp control (basic dial) goes to the mercury contactor. Leads go from the MC to the control strip which goes to the leads, which have current.

One thing has changed, one of the three heater lights is now lit. According to the manual, "When no voltage is goingthrough the heater panel, the heater circuit light is on, thus the teh heater circuits lights will be on when the dryer is off. The heater circuit indicator light goes off when voltage is going through the heater and heat is being supplied."



Wasted the entire day today working on this, and yesterday was a bust with the water pump going on the 4Runner, so any help will be much appreciated.

Shaun I am no electrical engineer, but did you disconnect the leads before you checked the resistance on the heating elements.

good question. yes, tried that

You have line voltage at the contact and wire feeding the elements, what do you have on the neutral side? Take your meter and check for voltage line to neutral and then to ground. Check then the neutral to ground.
If you find that you have power on the neutral side of the element to ground, then your problem is downstream of the elements.
Just re read your post.
Take your meter and read across the elements when they are powered, you should see the full voltage 230 vac.
Check your power supply and make sure that you have 230 vac.
I would suspect that there is a safety open keeping the elements from heating. (over temp or high limit) May be a fusible link.
Is there a wiring diagram?

Definitely not an EE question. Any good electrician can figure this out.

The heating elements should be connected in parallel to a voltage source. Therefore, whatever you did to the last element would have no influence on the other two.....probably. There may be some interlocks, but I seriously doubt it.

You say that the heaters each have 120 v going to them but no heat. You also say that 230v is going to the contactor and then to the heaters. So it sounds like the heating elements require 230 volts to work, correct? I also assume that there are two leads going to two connections on the heating element correct? If so, you need to measure the voltage across those two leads and not to ground. You should have 230 volts if I'm understanding your scenario.

The boxes should have nothing to do with the return path.

PROVISOS - THIS INFORMATION IS MEANT FOR INFORMATIONAL PURPOSES ONLY. I STRONGLY RECOMMEND THAT A LICENSED ELECTRICIAN PERFORM THIS WORK. I CAN NOT GUARANTEE THAT THE INFORMATION I HAVE GIVEN YOU IS ACCURATE FOR YOUR SPECIFIC APPLICATION, NOR DO I ACCEPT RESPONSIBILITY FOR FAILURE, CATASTROPHIC OR OTHERWISE.

This is a silly question, but are ALL THREE heaters supposed to have the same resistance? Or are they supposed to get colder the further down the line they are?

I did some more testing this morning and it may come down to a bad relay. there's a high capacity switching relay on the temperature controller board that, I believe, used to click (something did) when turning the temp higher. makes a lot of sense. When I pulled the relay, the base was wet and I'm guessing the capacitor gave up the ghost.

Before finding that, here's what I did.

There are three heating elements, I labeled I, II and II. The 2 leads going to each one were already labeled 1 and 2, 3 and 4, 5 and 6, respectively to I, II and III.

With the leads NOT CONNECTED, POWER ON:
I have continuity between the two terminals in each heater
For heater I, 120V connecting 1 and 2
N or G and 1: 46V
N or G and 2: 120V

For heater II, 75V connecting 3 and 4
N or G and 3: 10V
N or G and 4: 120V

For heater III, 79V connecting 5 and 6
N or G and 5: 13V
N or G and 6: 120V


With the leads CONNECTED, POWER ON:
For heater I, 0V connecting 1 and 2
G and 1: 120V
G and 2: 120V

For heater II, 0V connecting 3 and 4
G and 3: 120V
G and 4: 120V

For heater III, 0V connecting 5 and 6
G and 5: 120V
G and 6: 120V



Here's how the single phase install goes. There are 3 terminals and a ground

T1 is hot, T2 is neutral, T3 is hot, ground is ground.

T1-T2 and T2-T3 is 115V between each. T1-T3 is 230V.

The basic e- flow is:
T1 to a Mercury Contactor (each of the 3 black elements on the left of the control box)
Temperature controller to Mercury Contactor
MC to terminal strip
Terminal strip to heating element
T3 to terminal strip and then to heating element

Only wiring diagram I have
http://forums.pelicanparts.com/uploa...1231698877.jpg

macro view
http://forums.pelicanparts.com/uploa...1231698903.jpg

Terminals
http://forums.pelicanparts.com/uploa...1231698934.jpg

Controller face
http://forums.pelicanparts.com/uploa...1231699016.jpg

Controller wiring. note 1, 2 and 3 are mercury contactors. Circuit board closest to the center is the temp controller board. note that the black rectangle is the receptor for the relay.
http://forums.pelicanparts.com/uploa...1231699125.jpg

Board close-up. The 3 wires, red, green and black w/ spade connectors at the lower left go to the dial on the controller face. The braided wire goes to a probe that is inserted in heating element I.
http://forums.pelicanparts.com/uploa...1231699236.jpg

Wide angle of controller
http://forums.pelicanparts.com/uploa...1231699285.jpg

Shaun, have you tried to bypass heater control circuits to feed voltage direct to the heaters to make sure they are working?

I would Pål, but something tells me sparks will fly! I wanted to take an extension cord, cut it up, splice to one of the heaters and then plug it in to a 110V outlet to see what it does.


What is so discouraging about this was that I made real progress in getting this thing to work, then it dies with no signs why...nothing burned up on a board, smoke, etc.

Maybe I'm missing this, but you need to have everything together, turn it on, and check one heater, in this case term inals 5 & 6 -

http://img230.imageshack.us/img230/2...1698934fy8.jpg

Put the VOM (but really a "wiggy" would be my choice) across the leads 5 and 6 only, not at all to ground. Any reading other than 230v (approx) means the circuit is not being completed. This is the 1st place to start. I can walk you through the rest after you do this and tell me how much, if any, voltage you have.

PROVISOS - THIS INFORMATION IS MEANT FOR INFORMATIONAL PURPOSES ONLY. I STRONGLY RECOMMEND THAT A LICENSED ELECTRICIAN PERFORM THIS WORK. I CAN NOT GUARANTEE THAT THE INFORMATION I HAVE GIVEN YOU IS ACCURATE FOR YOUR SPECIFIC APPLICATION, NOR DO I ACCEPT RESPONSIBILITY FOR FAILURE, CATASTROPHIC OR OTHERWISE.

I am under the impression the elements operate at 230 v. Am I missing some information?

PROVISOS - THIS INFORMATION IS MEANT FOR INFORMATIONAL PURPOSES ONLY. I STRONGLY RECOMMEND THAT A LICENSED ELECTRICIAN PERFORM THIS WORK. I CAN NOT GUARANTEE THAT THE INFORMATION I HAVE GIVEN YOU IS ACCURATE FOR YOUR SPECIFIC APPLICATION, NOR DO I ACCEPT RESPONSIBILITY FOR FAILURE, CATASTROPHIC OR OTHERWISE.

OK, I get .01V on I, .003V on II and .000V on III (5 and 6)

Yet I get continuity between those two terminals with the leads disconnected.

Historically, III worked the best and I haven't touched it. I didn't work at all and welded the terminal back to the coils inside. II worked weakly and I did the same. After I fixed I, I connected it up (the raw element), laid it on II and I and III worked beautifully.

After working on II, nothing works.

Quick update. I get those same values when the relay is unplugged, so at a minimum, I have a bad relay on the temperature board. I think that's the culprit but I would love to SAFELY short the circuit without the temp board just to see if the heaters work at all.

OK, on the M, each has 4 contacts.
T1 goes to the top
Just below that, there's a blue wire that connects in series to the temp controller
Just below that is a white wire that connects in series to the temp controller
Bottom is black and goes to strip.

I would like to take a wire and bypass the top and bottom of the M's.

here is some additional testing.

Top wire on M (T1) to:
T1: 0V
T2: 120
T3: 210 all of these are what you would expect

Blue wire to:
T1: 120V
T2: 0
T3: 120

White wire to:
T1: 120V
T2: 0
T3: 120

Bottom Black wire to:
T1: 210V
T2: 120
T3: 0

I'm testing simply by poking the spear leads of volt meter to each lead. When test 5 and 6, I can either poke the screws on the strip or the leads at the heating element.


Here's an interesting test. voltmeter leads at top and bottom of M's reads 210V.

no gloves or safety glasses. I'm hoping to fry completely actually and just be done with all of this.

UPDATE

With a crude bridge between T1 and the strip contact for M for heater III, I donned the welding mask, rubber chem gloves and flipped the breaker.

III heated right up with 210 across 5 and 6.

So, do I have bad M's or I think more likely, bad temp controller, probably that relay was was wet at the base.

Thoughts?

Edit: I and II also work. can't tell you how happy I am about that! welding those coils together was something else.

Sounds like your temp controller is not sending the signal to close the contactors. If you feel compelled to test the heater elements, just disconnect the leads, tie to pigtail of a power cord and plug them into a 110 outlet. That should make the element hot.

I have no idea what voltage the contactors use. Could be 24VAC as it looks like there's a transformer on the temperature controller.

OK, your elements are fine. I would not blame the contactor (M), yet. You need to figure out how to get power to the contactors.

Shaun, without that relay in the temp controller, I doubt you'll get power to the contactors (blue and white wires).

When you're testing the contactors, put probes on the blue and white wires. If you get voltage there, you will know your temp controller is trying to close the relays.

I also think it's the temp controller or relay on temp controller, because it would be odd for all three contactors/M to go bad simultaneously.

nothing in between the blue and white, either across the Ms or at the temp controller board.

this may be good time to upgrade to a digital temp display versus a 1991 rotary dial to control temp.

Think this might work?

http://www.grainger.com/Grainger/items/6XR91

OK, so we are on the same page:
1) relay in the socket on the temp controller
2) temperature dial set to heat
3) no voltage across blue or white, correct?

That temp controller might work, but you gotta figure out what voltage is needed to close the contactors. Some temp controllers will output 24VAC, some DC, and others, full line voltage (110-230VAC). If you're not in a rush, you can find really good buys on digital controllers from eBay.

Does the relay have any markings like voltage? What about the transformer on the temp controller board? Any markings about voltage? Does the manual mention anything about controller voltage?

Also, you could bypass almost everything there with a temperature controller and 3 solid state relays (one per heater element) (about $100 total from eBay). I'd hate for you to spend that money, though, when it could be something really simple.

Just pulled it again. More weeping at the base even though it is vertically mounted.

Relay is an Aromat (now Panasonic) HL1-DC24V-H22

i found it here: http://www.onlinecomponents.net/search-results.cfm?searchtype=cont&startrow=51&prevstype= pnStart&SITE=&MFFILTER=&INSTOCKFILTER=0&SEARCHTEXT =HL&DOALL=1&MFLIST=

It's not in stock, no data sheet, but the it you go here to a similar one (not the same) it describes the relay. http://www.onlinecomponents.net/buy/PANASONIC-EW-AROMAT/HL1-H-DC24V/

this one as best I can read (white text on clear body)

15A 1/3 HP 125,250V AC
10A 30V DC
max 10 amp when used in a socket

I'm going to call the dryer mfg. tomorrow and see if they have one in stock. if not, I may have to create my own temp control (as you suggest) because these guys are very expensive in terms of replacement parts.

Each of the heating elements is $600. Elsewhere, $400, so a temp control from them may be cost prohibitive.

major issue right now is I'm getting behind in production (was supposed to have finished 250 handmade shirts this weekend...didn't even get to set up the infrastructure instead), so my hope is to get this thing working quickly and cheaply, then go back and make it better. It's an extremely simple machine, but my 1991 dryer that I paid about $1K for in a package deal goes for about $8K today, with the only difference being the controller interface, and no rust! :)

BTW, max temp will most likely be 400F or so. I'm tempted to steal the controller out of our heat press.

OK, so it is 24VAC for the contactors... still doesn't do you much good.

Can you get a hair dryer in relay socket to dry it out totally? Shame that a $8 part may be setting you back so many hours. You can definitely update that machine with a temp controller, 24V transformer, and 1 solid state relay.

Next time, I advise that you not shower with your equipment, k?

it looks to be that the relay itself is weeping, have no idea why or how. I dream of the day I have a shower again.

hi Guys,

Talked with the dryer mfg. no go on a new relay, and since they seem to be unobtainium, they recommended a digital controller. Basically, I'd plug the white and blue wires, as well as the probe, into the digital controller, cut an opening in the face of the box, install and be done.

Problem is it's $475.

Is there another relatively plug and play solution that is less expensive?

Plug-n-play and under $475? That's a tough one. You can certainly save money buying separate bits, but you'll be trading time for dollars. I'm thinking <$200 for separate temperature PID and relays, but it's not plug-n-play.

You could replace your contactors with eBay ID: 250355943670, but there are so many others that'll work just as well. Add some heatsinks to those relays.

Then, you'd need a temp controller, $30-150 (used-new), and you'd be ready to go with some wiring and testing.

A local electrical supply house recommended one of these. $282 delivered.

http://www.littletravelerusa.com/LDS765.pdf

Will it work?

I think that'll do the trick. Still not quite plug-n-play. Ask the supply house if the controller will work with contactors (3 in series) that require 24V. That is the only question for me. Don't forget you also need a thermocouple.
jurgen

Thank you Jurgen! I sent them the interior pic of the box as well as the wiring diagram I posted there to confirm that it will work. I've got the probe thermocouple, is that what you mean? Would rather go for the $475 component that is a guarantee, but for $200, I'll spend a little time on this as long as it CAN work.

Yep, that's what you need.

Too bad you couldn't get that system hobbling along for a while, so I could put together a small package to replace those guts. I think you're moving in the right direction, though.

good luck, jurgen

Thanks Jurgen and Bob, let me know if you guys have kids or grandkids and their sizes. Controller should be coming in on Thursday.

I wanted to get this up and running today and here's where I am at:

new controller
http://forums.pelicanparts.com/uploa...1232212795.jpg


old controller
http://forums.pelicanparts.com/uploa...1232212844.jpg


The thermocouple is obvious.

Blue wire went to N.O. on old board, so went to N.O on new RELAY 1.

Black wire went to L1 on the old board which is one terminal on the transformer, and this was bridged to C, as you can see in the pic. So I plugged this into COM on RELAY 1.

White wire went to L2, the other terminal on the transformer on the old board.


Big question: Where would the white wire go?

Second question: should I run power lines from the strip to the new controller? I would just bridge the conveyor belt motor strip terminals to the power connection on the controller.

Thoughts? Really don't want to melt $280.

Just checked the schematic. It's not polarity sensitive for AC or Dc. The label is just a "suggestion".

I'm not sure I understand your 2nd question. Do you just want to get power to the unit?

Did you get a new thermocouple with this?

PROVISOS - THIS INFORMATION IS MEANT FOR INFORMATIONAL PURPOSES ONLY. I STRONGLY RECOMMEND THAT A LICENSED ELECTRICIAN PERFORM THIS WORK. I CAN NOT GUARANTEE THAT THE INFORMATION I HAVE GIVEN YOU IS ACCURATE FOR YOUR SPECIFIC APPLICATION, NOR DO I ACCEPT RESPONSIBILITY FOR FAILURE, CATASTROPHIC OR OTHERWISE.

Thanks Bob,

They said my existing thermocouple probe will work fine with this. Just need to plug it into the 2 farthest right hand slots in the SIGNAL area.

On getting power to it, I believe it will either run with the power when the white and black wires are connected. if not, I can just run power leads from the strip to it.

It's the white wire that I don't know what to do with.

I guess I'm unclear as to what white wire you are wondering about.

PROVISOS - THIS INFORMATION IS MEANT FOR INFORMATIONAL PURPOSES ONLY. I STRONGLY RECOMMEND THAT A LICENSED ELECTRICIAN PERFORM THIS WORK. I CAN NOT GUARANTEE THAT THE INFORMATION I HAVE GIVEN YOU IS ACCURATE FOR YOUR SPECIFIC APPLICATION, NOR DO I ACCEPT RESPONSIBILITY FOR FAILURE, CATASTROPHIC OR OTHERWISE.

I'm sorry Bob. OK, on the original controller, there is a white wire, black wire and blue wire. The wires go from the original temp controller to the mercury contactors.

Based on markings on the old board and new board, I am fairly confident that I have connected the blue and black wires properly.

On the old board, the white wire is connected to the L2 terminal, one of the terminals on the transformer.

Problem is there is no corresponding L2 terminal on the new controller.


BTW, white is Neutral in the circuit.