225LX and 250EX questions.

I am wondering what the construction of these units is like. One area in particular is circuit boards. I have done quite a bit of electronics troubleshooting/repairs on amatuer radio equipment and power supplies and various other equipment. Are schematics and parts lists available for these units? What type of component construction is used on these units? Surface mount or thru hole or combinations of both? I am considering the analog 225LX and 250EX tig machines. I recently worked on a Miller 625 plasma torch and found pretty much a one circuit board unit. No schematic was found [or offered] after quite a long search. The cheapest circuit board price was 900.00 on that one. You would be surprised at how cheap some electronics can be repaired. Many that cannot be repaired are due to manufacter specific IC's that become obsolete almost immediatly. The Miller fiasco sort of generated my curiosity. No offense intended here. I just like to consider all options. I am what some would call a jack of all trades, master of none. I like to tackle just about anything that needs repair.

A few have asked about schematics or even basic block diagrams. None have been made available. So it looks like if you want that, you will have to reverse engineer them yourself. There have been a bunch of photos posted and it looks like mostly through hole type stuff. Also some of the high power parts are in module format. I did spot some SMD on the display board, when I took mine apart for some mods. On the plus side, most of it looks like basic commodity items and they don't try to obscure things by grinding off part numbers on chips and such.

I had some minor problems with my LX-225 that I took a crack at while waiting for a new board. The construction is (at least on my unit) through-hole on a double-sided PCB. The components all look common to me - CMOS logic (4000 series, and a fair number of analog multiplexers for signal routing), off the shelf op-amps, 78/79xx series regulators, relays to drive solenoids, diagnostic LEDs, etc, etc. Even a 555. The display driver is even one of those ancient Intersil A/Ds. Positively old-school, and to me it seems unnecessarily complex compared to how you might do it nowadays (throw a uC at it and be done with it!).

There's some conformal coating on the boards but it's the stuff you can solder right through.

PCB build quailty isn't exactly stellar, but my problems were unrelated to that. Also through holes seem to pull out a little too easily.

I can understand why they don't have schematics. Hardly anyone does anymore, and they say they change the design around from time to time so there is no one schematic. I do wish I could get some information on what some of the trim pots do, perhaps I should ask rather than just wish!

EDIT: I'm describing the control board mostly. Never had any trouble with the drive boards or HF (except where one of the HF points touched an adjacent cap). But nothing seemed too weird there.

Thanks Gents, Just the info I was looking for. Paul, Was your machine still under warranty and Were you successful with the troubleshooting on the board?

My machine was under warranty. I think at their discretion they'll let you do some work on the machine yourself if you have some electronics skills. This can work out great for both parties since you're not shipping a welder back and forth, and you're just waiting for a board to show up. Often times the welder will fail in a way that you can work around (loose the foot pedal for example) and so you can still use the machine while you're waiting.

I had two issues with my machine. First was a very common problem on the LX-225 where they had a bad batch of 4053 multiplexers. I just replaced the chip myself once support had diagnosed the problem since I had one anyway. The second problem was more mysterious. Something was shutting down the arc. I traced the problem to the "arc enable" (/SHUTDOWN pin on the SG3525 PLL controller which runs a driver which runs the power stages) which is controlled from various points on the control board (overheat, various timers and i/o, etc). I followed every wrong path on it until I isolated the around transistor V71, which I never really figured out what it did (the new board showed up). This seems to be controlled by some opto-isolated circuit (op amp, zeners, etc in the area). Frankly I was down to just a few components. In retrospect I should have isolated the "arc enable" wire at various places to more quickly diagnose what was shutting it down.

Ever since the board swap it's been working just fine.

The 210EXT appears to have surface mount components, according to pictures people have posted of the insides. It does come from a different factory than most of the other Everlast machines. Likely other machines made by that same factory would also use surface mount components.

Most of the other Everlast machines (including the older IGBT machines like the 250EX, 225LX, 200DX, and the older no longer available Mosfet machines like my Super200P) use through-mount components, which are definitely serviceable (if you have enough comfort with electronics to be able to diagnose the problem.)

FWIW, I've been pleasantly surprised at how available replacement circuit boards are for my old Super200P. Everlast supports their machines very well. I suspect replacement boards will probably be available for the the newer machines at a reasonable price. Everlast support is helpful in diagnosing problems and helping obtain replacement parts as needed, although schematics aren't generally available.