Millermatic 200 CR1 chattering

[JakeLB]

Hello have a millermatic 200 SN# JE777868. I replaced the CR1 relay because it wasn't pulling by itself all the way to push the contact points over. Now with the new ice cube style if you hold it for more then 2 seconds the points start chattering and it shoots small sparks between points. Seems like its getting too much power or else not enough power from transformer.

The drive motor does spin though, contactor W pulls in and gas solenoid opens but everything just chatters and bounces (HORRIBLE RACKET). Any ideas what may be wrong or how to go about finding issue?

How would I go about testing for 24V coming out of transformer wire # 32?

Any help is much apprecited. Thank you!

[MAC702]

My first guess is that you just got a bad part. It happens. When I come across a chattering contactor or relay, I replace it.

I also don't buy OEM parts, which are usually too highly marked up on price, and may be why you are hesitant to do the repair twice. Generic contactors are cheap, and you probably have the same odds on failure rates.

[JakeLB]

Well I just bought a generic part $20 so not bad. Agreed OEM is rip off miller wanted $175. I'll see if maybe I can exchange since it came from Amazon.

The only reason I think its transformer not sending a full 24v to coil is because on the old open style it would only pull halfway as if it didn't have enough magnetic power in coil to pull it fully.

[MAC702]

Ah, well, that's something. On the contactors I see everyday, the coil connections have plenty of bare spots to stick my voltmeter probes and get a reading while in use, but I fix air conditioners and not welding machines, so am not familiar with your parts.

[Aeronca41]

Did you see this welder working before and it just developed a problem, or is this a machine you just acquired? Are you running on 220/230 volts or do you have three-phase power and feeding it with 208v ? It does sound like you aren't getting full voltage to the relay coil. You should be able to see the coil connections on the relay-you must have hooked them up when you installed the ice cube relay in place of the old open-frame one. They are wires #16 and 32. You can check the transformer voltage by measuring between wire # 30 (attached to the diode bridge) and wire # 32, which is hooked to the relay coil.

Most obvious failure possibility is the circuit breaker CB1 is failing and not making good contact. You aren't showing any signs of an overcurrent condition, so my next step would be to get the relay chattering and then bypass CB1 with a piece of wire to see if the chattering stops. It is mounted on the center panel, near the wire feed motor. There are also a number of connector pins that could have bad connections, or your trigger switch on the gun could be making poor contact.

[JakeLB]

OK thank you Aeronca41. that is really helpful, I'll try both those when I get home.

Note: I am very much a beginner on figuring out electronics!!!!! LOL

I am running it 220/230 volts.

So when I bought it the old open style CR1 relay pulled but not wire fed or contactor pulled or gas valve opened. So my friend tells me "spray it down with WD-40 mine worked great after I sprayed mine down" So I did and after that the CR1 wouldn't pull fully open anymore. After trial and error and mainly error I realized the 5amp fuse on front panel was missing....(weeper right?)

So I bypassed the fuse. CR1 still wouldn't pull by itself, so I manually switched the CR1 relay and BAM the contactor pulled, wire fed and gas valve opened but everything chattered really bad. So I unplugged the contactor and gas valve to try and diagnose which was chattering, and CR1 was still bouncing so my guess was it was making everything else bounce and chatter

I will try bypassing CB1.

it is flippin dirty inside which is why I am wondering if the connector pins are really dirty and need to be cleaned and maybe spraying wd-40 have created a layer of non conductive film in between connector pins?

[Aeronca41]

MM200 is without a doubt the nicest MIG machine I've ever used. It obviously doesn't have all the modern bells and whistles, but for just burning wire, it is fantastic.

CR1 would definitely make everything else flop around if it's chattering, so you are on the right track. Do be careful in there--one hand in your pocket all the time when working on hot circuits--use clip leads. Never two hands inside the machine at a time. Here's the manual if you don't have one.

https://www.millerwelds.com/files/owners-manuals/O1303J_MIL.pdf

If you look at the schematic diagram on page 28 at the top left, you will see CR1 in the circle. Notice the jumper connections at the very top of the diagram. There is a jumper wire between pins 5 and 6 of PLG 1; could be dirty or corroded. I'm pretty sure the pins to right of that (RC1, pins 1 and 2) are the pins on the front panel connector where the small wire from the trigger switch in the MIG gun plugs in. Assuming you have found the transformer is putting out 24 volts, and jumpering the circuit breaker didn't help, here's another thing to try. Once again, get the relay chattering and try bypassing all of those jumpers and connections by connecting a jumper wire from wire #30 on the diode bridge to wire # 16 going to the relay coil. Be sure to find a way to connect to those wires safely. That will take all the connections, including the gun trigger, out of the circuit. If any of those connections or the trigger are bad, you should see it stop chattering immediately.

[JakeLB]

Alright so i checked volts at wire #30 on bridge and #32 on CR1 i only get about 13 volts. So i jumpered wires #30 and #31 on CB1 breaker and i get 24 volts and no chatter on CR1!!!!!

now when you say bypass CB1 completely do you mean hook all the wires into one clump or connect #31 and #32 as one and then #21 and #3 as another?

one thing to note i do get a small spark on Cr1 relay when it first hits and when i release not sure of thats normal or not.

Thank you!!!

[G-ManBart]

one thing to note i do get a small spark on Cr1 relay when it first hits and when i release not sure of thats normal or not.

Thank you!!!

Going off memory, that's normal...

[walker]

Since it is a new to you machine, have you checked the jumper position?

[Aeronca41]

Great! You found it.

I agree with Bart--some sparks at the contacts when the relay opens and closes are not out of the ordinary.

You need to find a replacement CB--I would not keep on welding with no overload protection in that circuit--if one of the bridge diodes shorts or something else goes south, you don't want to toast your machine. The parts list in the manual says it's a 0.7 amp manual reset circuit breaker, which you might be able to get by taking the old one to your local electrical supply place. There is probably a manufacturer name and part number on the old one, and you should be able find it or a substitute. You may have to tweak with how it's mounted, but any .7 amp breaker will work. I'm sure you can find something at Mouser, Digikey, Allied, etc. on line.

I am a bit confused by the wire numbers you mention. Looking at the diagram, I don't see those numbers hooked to the breaker. But, just install the new breaker with the wires connected as the old one and you should be good to go.

[JakeLB]

This is the wires #21 and #3 which im talking about. I think anyway cant actually read a schematic if my life depended on it lol!!

dude your the best shoulda come on this forum months ago!!! Ok I will find me a new CB1 and hook it up.

Thanks for your help all!!

[Aeronca41]

This is getting more interesting--I only saw the portion of the breaker in the schematic I posted. That must be a two-pole breaker--are there four terminals on it? Might be a little harder to find.

[JakeLB]

Yes it is a 4 pole breaker see attached picture.

so what i was wondering before is i jumpered 32 and 30 wires to get cr1 working, but can i jumper 3 and 21 as well to get wire feeding? Would i jump 3 and 21 as a seperate circuit or jumper all 30, 32, 3 and 21 together as one? Im guessing my first thought of doing them seperate is correct but dont wanna overload something!!

[JakeLB]

Sorry 2 pole not 4 pole....has 4 connector terminals