Hobart 125 gas control issue

[Taylor43]

Alright as soon as i plug my welder in my gas valve opens. When the welder is on the gas is always on as well. It just started doing this one day when i plugged it in. If i disconnect the contacts to the gas valve it will close. I can remove and connect one of the contacts and it will stop and start gas flow so i don't think anything is wrong with my valve. As soon as i plug it in the connections from the circuit board to the gas valve constantly have 120V. Could my circuit board be fried? The gas valve isn't dirty and seams to be operating fine. I tested the trigger and i don't think it is the issue


Anyone have some experience with an issue like this? Thanks in advance guys.

picture for reference.

 

[shenion]

Sounds like a stuck relay on the control board.

 

[Taylor43]

Can i go about replacing a relay on the board or does the entire board have to be replaced?

 

[Taylor43]

picture for reference of what i need to repair

thanks in advance

 

[Jake SS]

PCB should have 2 relays, 1 feeds motor, other gas valve
Check relay CR2 if it is marked, should have NO contacts and NC contacts.
Once triggered both relays will close
Coils are on same circuit

 

[Taylor43]

alright would you guys suggest repairing this board if possible?
or getting a new one from hobart?

 

[shenion]

If you are comfortable repairing the board then do it. If not, have someone else repair it or just buy the board.

It it still under warranty?

 

[Taylor43]

I purchased the welder used and it was working fine for the past months then this occurred so i don't think i'm going to have any warranty being the second owner. I have all of the supplies to do this accept for the replacement relays on the board. i know i should be able to pick these up at a local industrial electronics store in town. Could you please help me identify specifically what relays on the board i should be replacing i can get high res shots of the board to help.

thanks for your help

 

[shenion]

You should be able to trace the wire from the solenoid, to the board and then to the relay that is used.

 

[Taylor43]

Alright guys i labeled all of my wires and removed them along with popping out my board from the welders case. It seams 6 and 8 lead from the gas valve to the board. I have identified relay cr1 and am going to take it in to get it replaced. If i can take any other pictures to aid everyone in helping me just let me know. i will let everyone know if this solves my issue. No one in town can get me a replacement relay and it looks like i am going to have to source one online. Anyone know a good place to order this relay?

the markings on the relay say

NT90RHCS24CD
NO:30A/240VAC/14VDC
NC:20A/240VAC/14VDC
DC24V

thanks to all!

 

[Jake SS]

C2 is a capacitor

CR2 is the box under RC5 RC6 terminals

You should be getting about 26VDC between RC4 and RC2-10 (common), coil of relay, if that is present then relay should operate, if not turn off machine and measure resistance of coil terminals of CR2, would be around 1.2Kohms give or take,
If all that checks out then contacts of relay must be faulty

There is a resistor R6 in series with the positive supply side of CR2 coil, check that

Also have a good look at all soldered joints for cracks or dry joints, use a magnifying glass, you may think your eyes are OK but believe me sometimes dodgy joints are not easy to detect with eyesight

Try this first

Cheers

 

[Taylor43]

i haven't had a chance to test the relay yet but if its toast and i need to get it replaced does anyone know where i could pick this part up online? the industrial electronics store in town couldn't source this relay for me.

the markings on the relay say

NT90RHCS24CD
NO:30A/240VAC/14VDC
NC:20A/240VAC/14VDC
DC24V

 

[R Kraft]

It looks like a T90 style relay, you might look at the r53-5d20-24 or something similar,though it is a bit short on amps.
These guys say they stock them :http://www.geirelays.com/html/overstocked.html
And these guys make them:http://www.forward-relays.com/product/product_images/p/en_p__106.pdf
Robert

 

[Taylor43]

I had the board professionally checked and they gas relay had failed and its been replaced and now in working order until my wire drive engine lost power