Parweld XTT 202P TIG welder.


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Hi,

Having reached our 43rd wedding anniversary and with my birthday imminent Bron kindly asked what I would like as a prezzie; I opted for a Parweld XTT 202P Tig welder. I had seen one on Gumtree where a guy had bought the welder brand new but never used it having it stored under his bench for a year so I ended up with a brand new welder at a nice price including delivery.

Once the welder arrived I unboxed it but couldn't try it out because it needed Argon gas as I intended to weld aluminium; eventually I bought the gas and having the welder loose with it's assorted hoses and gas cylinder for safety I made a welding trolley but used my oil filled arc welder to weld the trolley. I bought Tungstens; collets and collet holders for the torch; aluminium welding filler rods were bought as was a gas flow meter; then I bought two large sheets of aluminium; yes TIG welding doesn't come cheap and the cheap TIG welders don't weld aluminium these being DC machines only; the more expensive machines have both AC and DC; AC is needed for aluminium.

Whilst gathering all the kit I was working in the gardens but at last I finally tried TIG welding for the first time with terrible results; I couldn't see the weld puddle so quit to do a bit of research. Whilst browsing for TIG welding helmets on eBay I noticed helmets of the type I already have that I paid £35 for a few years ago; I've seldom used the helmet and only on arc welding where it was fine but I was taught to use a hand shield. What I hadn't realized was that the helmet I already have has adjustable lens and of course with my bad luck it was set at darkest #13 DOOOOOOOOOH.

I'm a member of a MIG welding forum and a member on the forum was stating how brilliant his new welding helmet was; this helmet at around £400 each through eBay is an Oprel Crystal 2.0

https://www.optrel.com/en/eye_protection_helmets/products/show/crystal20/

I collected my new helmet a few days ago but with working in the gardens couldn't play straight away with the welder. At last I had a clear day so I was keen to get into the workshop and have a proper go at TIG welding; WOW what a startling revelation this new helmet proved to be; I can use it for all my welding in future and it's absolutely brilliant. Now I could see the welding puddle but being a novice TIG welder was blowing holes in the aluminium; as I settled more I kept adjusting the welder controls and was finally making positive progress when there was an explosion followed by a dense cloud of smoke. My new welder had blown up big style. I quickly switched everything off and opened the workshop door to let the smoke disperse which was still billowing from the welder; satisfied the welder was now safe and not about to burst into flames it was mug of tea time and a think.

First job check the warranty; typical of my bad luck the warranty isn't transferable which doesn't surprise me at all so now I had expensive scrap and dashed hopes of TIG welding. I'm very used to restoring machinery before I use it but this is a first for me in restoring a brand new machine but as it wasn't covered by warranty out came the tools.

Blown welder_0006.JPG


I stripped the welder of its covers and above shows what confronted me; two blown electrolytic capacitors 1200uF 200V.

Blown welder_0007.JPG


The small circuit board had to be removed in order to gain access to a mounting screw for the larger board.

Blown welder_0008.JPG


The welder as it currently is sitting on the bench; new capacitors are ordered from RS and should arrive within the next few days; as I say nothing but bad luck; it's a bank holiday meaning a delay in receiving the capacitors.

Circuit board_0002.JPG


The underside of the circuit board; the two large square items to the left are full wave bridge rectifiers; not wanting to install two new capacitors with risk of blowing them again I've tested the rectifiers and they are in good working order giving readings each of .556V Had I not tested the rectifiers with my luck I'm sure they would have been faulty; when the capacitors arrive I'll install them then put the machine fully back together.

A WORD OF CAUTION: ELECTROLYTIC CAPACITORS ARE DANGEROUS COMPONENTS: THEY ARE PRONE TO BEING FULLY ELECTRICALLY CHARGED EVEN WITH POWER OFF AND ISOLATED FROM THE MAINS SUPPLY ALSO IF DYNAMICALLY TESTING THEY SHOULD NEVER EVER BE VIEWED END ON BECAUSE THEY CAN BLIND IF THEY EXPLODE.

I'm not in the least worried about the welder expiring just putting it down to my continuing bad luck. At first I thought due to my inexperience at TIG welding I had done something wrong to cause the problem but members on the welding forum assure me this is highly unlikely much to my relief.

Welders can be repaired professionally but possibly at high cost; I don't encourage anyone without electrical knowledge to even remove the covers of a machine of this kind; not only can electrolytic capacitors give a nasty shock just by handling a circuit board can cause lots of collateral damage to static sensitive electronic components.

Petrol tank_0002.JPG


I'm dreaming of TIG welding this new aluminium petrol mower tank I've made; I've seen similar on YouTube but I like to do things the hard way so decided domed ends would look better so I metal spun both domed ends on my Graduate woodturning lathe.

Petrol tank_0001.JPG


Above is the metal spinning wooden former being turned from hardwood; this is rough turning; it was finished to close tolerance allowing the domed ends to be a tight friction fit. The aluminium round tube I bought as a long length through eBay it's 4" diameter.

I'm only adding this thread for interest because it's unusual and the sort of thing I get up to whilst in my workshop.

Kind regards, Colin.
 
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Ian

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Good detective work!

I wonder why those capacitors blew - did the welding forum have any thoughts as to why it happened? Are you getting the same ones, or ones rated at higher than 200V?
 
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Hi,

Thanks Ian. The welder had been bought new then stored under a bench for over a year before Bron bought it for me so in effect it was still a new welder. Unfortunately electrolytic capacitors have a shelf life and the ones installed are only rated shelf life 1000H so standing for a year plus however long it was before they were manufactured I think this to be the main reason they exploded. I'll not repeat myself because for anyone interested the story is on the welding forum;

https://www.mig-welding.co.uk/forum/threads/blown-my-welder-up.94007/

With my bad luck if anything can go wrong it will and if it can't go wrong it will. I've fully restored lots of things over the years but this is the first time I've had to restore a new machine. I'm still awaiting the new capacitors.

I'm using original spec caps Ian; it's tempting to upgrade to a higher voltage but I'm unfamiliar with the electronic circuits on this welder and charging higher voltage caps up might have a knock on effect destroying other components; I know you're very aware that just touching by fingers can destroy static sensitive components so I'm being careful.

Kind regards, Colin.
 
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Hi,

I decided to upgrade the caps on the welder; not to increase uF value or voltage but to vastly increase quality at a high cost. The board has six identical caps installed and given that two of the original caps exploded the cheapest option would be to simply replace these two but I never ever bodge or take the easy way out. With all six caps identical I feel had I replaced just the two and reassembled the machine I'd never trust it expecting the next explosion at any time; the original caps from brand new only had a shelf life of 1000H which is ridiculous considering the caps could be in store for over this period before even being installed.

I've decided to upgrade from these cheap original caps to Kemet caps of the same value and voltage but they are slightly bigger and a great deal more expensive but with a shelf life of 3 years;

https://uk.farnell.com/kemet/alc80a122dd200/cap-1200uf-200v-alu-elec-qc-snap/dp/2950791

I have two Kemet caps which this morning I tried for fit and then installed them; I've now got four more of these on order for early delivery next week; the board is already prepared so once the Kemet caps arrive I can solder them straight in and reassemble the machine; I hope the exploding caps didn't cause collateral damage to other components but I'll know pretty soon; one thing is certain; with these new caps installed the board will be vastly superior to the spec when it was new.

Kind regards, Colin.

Capacitors_0003.JPG


The original caps removed and holes ready drilled to accept new caps.

Capacitors_0004.JPG


Two new Kemet caps soldered in four yet to do when they arrive.


Capacitors_0005.JPG


The original six caps these very poor quality indeed.
 
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Very nice Colin. I’m relatively sure that thousand hour rating must be for when the welder is actually being used. Still, that’s only half a year at 40 hours per week.:oops: Be sure to update us after you get it repaired.
 
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Hi,

Many thanks Doug. :) I believe shelf life starts immediately after production as is the case with capacitors; however the length of life of electrolytic capacitors can be significantly increased by reforming?

https://www.dfrsolutions.com/hubfs/Resources/services/Long-Term-Storage-of-Al-E-Capacitors.pdf

There is lots of information on the web regarding electrolytic capacitors with just an example above; I appear to have bought industrial rated capacitors in these Kemet's hence the much higher price I paid for them meaning if the welder runs after the repair I can relax not wondering when the next explosion would occur had I left the undamaged remaining four capacitors in place.

https://dictionary.cambridge.org/dictionary/english/shelf-life

I've just had a quick look for shelf life and above is an example. Food stuffs are generally sold with a "use before date".

I'd be interested if data were available as to how many of these circuit boards have failed in service.

I've restored vintage radios and having restored them ignored them for a long period of time only then when I switch on to be greeted with a loud bang as an electrolytic capacitor expired however things like TV's seldom suffer this due to the TV being in regular use; electrolytic capacitors don't like being unused and stored for a long period of time; at the moment I'm still unsure what actually caused the capacitors to explode on this welder but shelf life is my main suspect?

All I wanted to do was to have a go at TIG welding and Bron generously bought me the welder whilst since I've spent even more money on consumables and the new expensive welding helmet; I've actually had a go and it lasted less than ten minutes so far it's been hugely expensive for a ten minute hobby?

Kind regards, Colin.
 
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I feel confident you will not only figure it out but will become extremely proficient at tig welding. Admit it - if everything had gone perfectly and there was nothing to repair, you would have felt let down. ;)
 
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Hi,

You certainly know me Doug; I'd have passed out with shock had everything or indeed anything had gone to plan; thanks for your confidence I hope I can live up to it. :)

As usual not just one problem but problem one after another and this time the cooker oven couldn't wait to pack in; after checking part numbers etc I've just ordered and paid for a new oven element; genuine part of course it being a Stoves and costing £40 including next day delivery; a non genuine part could have been bought for half this but I think it false economy especially since it would most likely cost the £40 just for a service engineer call out?

I did a resistance test on the element just in case the fault lay elsewhere after all I've lived with bad luck for so long had I bought the element without checking the fault would most likely be the switch.

I had been working on the computer when the power went off and tripped one of the main RCD's so I knew it must be something major or just the mcb would have tripped; the RCD reset without problem and although I checked everything I couldn't find what caused the trip? The oven was still hot and the fan running so I discounted this until Bron said the dinner seems to be taking a long time to cook; so the welder is down and now the oven is down bring on the third because whatever it is I'll sort it out. o_O Twice I had to visit the workshop and twice my pet cloud Blackie was waiting for me; now I'm indoors the sun is shining.

Yes I think I'd be bored if things went to plan.

Kind regards, Colin.
 
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Hi,

An update. I replaced all six caps and was pleased when I fired the welder up intending to let it run for an hour before attempting to use it; the welder sounded fine and the panel was lit up for a few minutes until there was a loud click as the mcb tripped again?

Now I had serious problems because I didn't have a circuit schematic to work from. I emailed Parweld asking if they could please supply a schematic and also what a new power circuit board would cost this was yesterday.

I also emailed Wakefield Welding Centre asking for a rough quote regarding repairs?

Early this morning I received a welcome reply from Jim in Wakefield asking me to please leave it with him and he would get back to me tomorrow.

Also early this morning I received a reply from Parweld kindly sending me the schematic and also asking for more information regarding the board identification. I went down to the workshop and noted all the details on the board then returned to my computer but I then noticed a second email from Jim asking me to please phone him which I immediately did.

It's a good job I was sitting down because I filled up with emotion as Jim explained he had been in touch with Parweld upon my behalf who in turn had agreed with jim to repair my welder under warranty which I'm truly thankful for. I've already met Jim as I took my welder over to him and a bonus is I now know where to buy welding consumables in future. I'm just amazed.

TOP MARKS WAKEFIELD WELDING CENTER AND ALSO HOPEFULLY WHEN THE WELDER IS RETURNED IN FULL WORKING ORDER TOP MARkS TOO TO PARWELD: I'M DELIGHTED AND CAN NOW GET ON WITH MY LIFE. :)

The oven element also arrived from espares this morning and within five minutes we had a fully working oven again. What a good day for a change and at last my continuing bad luck is changing for the better.

Kind regards, Colin.
 
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Hi,

You might want to check - Blackie might be gone too. :)
Many thanks Doug. Miracles don't happen; puddles again this morning before the day gets under way and it's dark. Unfortunately Blackie has taken a lifelong shine to me for some reason; his sister Gale has also been here over the last few days too but then this is normal. :(

Hopefully the four roller blinds will arrive today then I can trim them to size and install them ticking another job off; I still dream of getting into the workshop without jobs hanging over me all the time but I can dream on. I wonder if the family of badgers have been digging in the garden again leaving a big deep hole; it never lets up here doing what I have to do rather than what I'd like to do; I'm not bored.

Kind regards, Colin.
 

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