Stealth ac/dc200 HF failure

[Morris]

I have had my Stealth ac/dc 200 for seven years now and it has done all I wanted.
Today the HF stopped working. It has been a bit erratic lately but I put it down to anything but imminent failure. I have removed the cover and blown out any dust, although there was very little.
I could always hear the HF "sizzling" on start but now nothing. It is not a spark gap, it's a small coil on a board. Connections checked and had a look for burning etc, nothing.
Any thoughts before I send it for repair and if I have too where would people recommend? Any where in Northamptonshire?
Couple of pics showing the parts.

The transformery bit, the thin white wires come from the HF module.

The HF module with what looks like a small ignition coil (which I suppose it is). Nothing looks amiss.

Thanks.

 

[voipio]

There are a couple of "dribbles" of something on the bottom of the case. Any clues to where those came from? Also some on the bolted assembly in the second image, below the ignition coil.

 

[Morris]

They are some sort of mounting/potting compound, there from day one.

 

[Anguz]

Have just sent you the number of a guy who fixed my hobart

 

[Morris]

Thanks Angus. I don't suppose you know where he is based.

 

[Anguz]

Northampton

 

[Morris]

Cracking!
Thanks.

 

[Luggsey]

Capacitors drying out are a favourite on any high power pcbs.

 

[Morris]

It's now gone back to SWP, we'll see what they have to say and how much it will cost.
Guy in Northampton didn't want the work.

 

[Morris]

SWP are sending my Stealth back unrepaired as they do not have replacement HF units. They are not charging.
I spoke at length with Jim Davey this morning (top bloke) who gave me several pointers for when it gets back. I'm hoping that one of his universal HF boards can be cajoled to fit. If not he has recommended Tec Arc in York.
I'll update as things progress.

 

[MetalMonkey]

Hmmm. Doesn't bode well for something that has been advertised as having the U.K. back-up of SWP as one of the key features for buying it....

 

[Morris]

Hmmm. Doesn't bode well for something that has been advertised as having the U.K. back-up of SWP as one of the key features for buying it....

It's 7 years old and this model was superceded fairly quickly. I'm guessing that the Chines manufacturer couldn't be bothered to support them with spares. The newer ones have a 5 year warranty if I recall correctly.
Still a bit disappointing but I'm not quitting yet.

 

[blobby1]

Hi. On some of their machines they used a blue disc sealed spark gap, if it is you can try removing it and put an open spark gap in.

 

[Morris]

Good information thanks. Varistors and capacitors can be blue discs as well so hopefully I can identify the components if I need to.

 

[Morris]

Welder came back on Thursday but I had something I wanted to weld up first so scratch start it was.
Today I have started to investigate a little. The board is fed from the main control board and in addition has the HF coil connections out. that's it.
The feed from the control board appears to give 180Vac when the torch button is operated so it looks ok there. There appears to be nothing blown or burnt out on the board.
The board is marked FR200H3. I tried a few varied searches in the hope that it might be a generic board but no joy.
Here's some pics to keep you all amused while I dig deeper.

 

[blobby1]

Hi. see the white thing with green writing in front of the 4 blue varistors, it's a lightning arrestor used as a spark gap and over time they get coked up, try repalcing it another spark gap. If that doesn't work it might be the transformer.

 

[Morris]

I had thought that's what it was. Do they come with varying gaps or ratings?

 

[Morris]

Now back from Technical Arc after board level repairs. It was away for three weeks and cost was just over£200 including VAT and shipping.
It now starts better than when it was new, well pleased with it.