TIG Welder Overheating - Page 1
Forum section: electronics / beginners

author: masterkorp
author_rank: Contributor
timestamp: April 06, 2015, 09:28:38 pm
content: Hello everyone,Soyesterday my TIG Welder decided to stop working.The welder only welds for 2-3 seconds and the it just stops welding. The overheating light just comes on. But I am pretty sure it ain't overheating.So I opened the welder and I think I found the temperature sensor.I've tried the following:- Disconnecting the possible sensor makes the same result, which either means I am totally wrong or the sensor is totally dead and the circuit has a failsafe when no connectivity at is given- Shorting the pins together makes the overheating light immediately come on. (Without start welding) which kinda enforces I am on the right track- The pin has 24v when machine is connected- I could not read any resistance values from the possible temperature sensor.I think what I will try next is buying a 10k, 1k and 100 ohms resistance and connected them to the pin and check if I see any change in the behaviour.Any ideas are welcome! I really need this machine to work.

author: jlmoon
author_rank: Unknown
timestamp: April 06, 2015, 09:57:36 pm
content: Some documentation and more data would best to determine your problem.It is highly recommended not attempting any unknown resistor shunts or bridges unless you know what you're bypassing or shunting.Schematics or service documents are your top priority.

author: tautech
author_rank: Super Contributor
timestamp: April 06, 2015, 10:15:13 pm
content: In an inverter style welder the are 2 possible locations for the sensor, in the transformer and on the switching device heatsink. Maybe both.Which is yours?Can you remove the sensor and post a photo?

author: masterkorp
author_rank: Contributor
timestamp: April 07, 2015, 10:37:05 am
content: Quote from: jlmoon on April 06, 2015, 09:57:36 pmI could not find any schematics of this china welder. Please if someone could get me anything I would be thankful.Quote from: tautech on April 06, 2015, 10:15:13 pmMine is an inverter style welder. I do think I am correct with the sensor location (last attached picture)

author: jlmoon
author_rank: Unknown
timestamp: April 07, 2015, 01:58:40 pm
content: Can you post the Manufacturer & Model Number ?

author: Seekonk
author_rank: Super Contributor
timestamp: April 07, 2015, 06:39:02 pm
content: Even though it says over temp light, these often serve multiple functions. Unplugging the sensor and having the light come on immediately makes me believe the fault is not overtemp at all.

author: masterkorp
author_rank: Contributor
timestamp: April 08, 2015, 09:34:40 pm
content: So I yesterday night I've made a tool to extract the temperature sensor.And as it turns out itsa fuse not a sensorThe fuse is BR-B2D at 95C apparently its the 24vdc version since the voltage coming of the pins is 24vCurrent conclusions are:This is why disconnecting the sensor/fuse had the exact same effect has with it on.Also explains why the light comes one immediately after shorting the pins together, no matter what resistor I put in thereThe problem may be elsewhere, which means I am fuckedI really need and try to find the schematicsQuote from: jlmoon on April 07, 2015, 01:58:40 pmI wish I knew this, but it seems that the manufacturer and model is not mentioned anywhere on the machine. No documentation came with it.The best I can do I topost a link to a very similar machine from the exactly the same seller I bought.I have a friend that has that exact model and its working fine so far. I've compared pictures from both machines and they look exactly the same.Also i've tried that email, and I get no answers.Any input would be very welcome at this point! As I am really out of budget for a new proper machine, and I really need this working,

author: masterkorp
author_rank: Contributor
timestamp: April 08, 2015, 09:58:26 pm
content: Another link of thesame welder I have

author: Psi
author_rank: Super Contributor
timestamp: April 09, 2015, 06:16:29 am
content: I think a lot of these welders are copy's or rebrands of jasic weldersThe same temp led may get tripped from overcurrent which could happen if one of the power FETs/igbts is a bit faulty but not totally dead.If it was me I would be checking all the power FETs/igbt's first because a fault there won't trip a fault condition forever. Repeated attempts to start it with a partial short will damage it more until Bang! And then you'd need to replace all the FETs and maybe more.Just my thoughts on it

author: masterkorp
author_rank: Contributor
timestamp: April 09, 2015, 10:11:22 pm
content: Quote from: Psi on April 09, 2015, 06:16:29 amThanks for the info.QuoteOk, how do I do that ?

author: masterkorp
author_rank: Contributor
timestamp: April 09, 2015, 10:18:52 pm
content: I followed the circuit and it seems to be like this:D6 (the red led) ->R30 -> R29 -> R28 -> (to the PCB that is vertical) -> R22 -> R21 -> C12 -> Q4 -> Q3 -> R15 and the goes to the most upper left pin of that mosfet/whatever.It was that number BCPB-K01-D which agoogling gives me nothing.So I've tried to remove that sticker and check if there is anything under it.And it seems to be this number VA28A 3525A which then again google gives me nothing.Some new questions:How the heck can I find information about these numbers ?Can I debug this with just a multimeter ?

author: mentaldemise
author_rank: Regular Contributor
timestamp: April 10, 2015, 02:32:54 am
content: Might it be one of these:https://www.fairchildsemi.com/datasheets/KA/KA3525A.pdf

author: masterkorp
author_rank: Contributor
timestamp: April 10, 2015, 02:31:47 pm
content: Quote from: mentaldemise on April 10, 2015, 02:32:54 amThanks, how can I test if it working correctly ?

author: masterkorp
author_rank: Contributor
timestamp: April 12, 2015, 01:30:44 pm
content: Hello everyone.So I completely disassembled the whole welder and inspected all the board and such, and found this:And found what seems to be a "nose monkey" shorting those 2 pins together, also completely sprayed all the PCBs with electrical cleaner spray and the welder works again!I had almost a week of downtime on this machine. I have a lot of work to repay for.This being said. I plan to get a proper machine long term (I always wanted but no budget for it yet).Thanks to everyone that helped one way or another !

author: Tallie
author_rank: Regular Contributor
timestamp: April 12, 2015, 03:25:22 pm
content: Glad you got it fixed! My guess would've been the spark gap(assuming it has one).

author: masterkorp
author_rank: Contributor
timestamp: April 12, 2015, 05:11:23 pm
content: Quote from: Tallie on April 12, 2015, 03:25:22 pmWhat is the "spark gap" ?

author: Tallie
author_rank: Regular Contributor
timestamp: April 12, 2015, 06:54:17 pm
content: Quote from: masterkorp on April 12, 2015, 05:11:23 pmWorks the same way as on a Tesla coil... basically. It allows the circuit capacitance to charge and discharge.

author: tautech
author_rank: Super Contributor
timestamp: April 12, 2015, 07:39:04 pm
content: Quote from: Tallie on April 12, 2015, 06:54:17 pmYep, it's part of the HF circuit for easier arc establishment at start of welding.Older welders would whistle when HF was engaged.Pretty much outlawed now because of the horrible EMI interference it creates.I'd expect in this one if it has an HF mode it done electronically.@masterkorpYou can put off that eye test for a bit now.Good find, well done.

author: masterkorp
author_rank: Contributor
timestamp: April 13, 2015, 10:55:16 am
content: Quote from: tautech on April 12, 2015, 07:39:04 pm

author: G7PSK
author_rank: Super Contributor
timestamp: April 14, 2015, 07:44:09 am
content: All the modern TIG units that I have had use an HF block that cannot be serviced as not only are the electronics encapsulated the whole thing is moulded into a plastic case, on the other hand the best TIG unit I ever had was an ESAB unit made in the late 50's or early 60's and the HF unit consisted of a Bosch spark plug and ignition coil and some very high voltage silver mica capacitors, it was built like a tank weighed 280 KG including the transformer which was in over 100 litres of oil and would run 400 amps all day no modern unit would touch it. And the idiot that I am traded it for a modern light weight unit just for one job where I neede to get it up some stairs.

author: Kuria
author_rank: Newbie
timestamp: November 27, 2017, 06:13:40 pm
content: I Know this an old post but I have a similar problem. My welder OC light is always on and while the machine switches on and the knobs and display seem to functionIt's doing nothing it's blocked. I wrote a lengthy post on it ..... Any advice?