Help with dead inverter welders
Gary Slater
I have a few 240V - DC inverter welders which have I have salvaged from my
workshop.
I have:
Esab LHN 140
Esab LHO 150
Miller Goldseal 140
Each one of the above are dead machines which went "POP" and stopped working
(words of my faithful employees) while being run from a generator on site
jobs. I suspected the machines had problems with power spikes etc etc. ..
from running on a generator which doesn't have real smooth power control /
too small etc etc...
I have got some advice from an electrician mate who suggested running a
small inductance motor from the generator while using the welders to soak up
these irregular "spikes" which I have arranged, and am now using a new
machine (Gismi 140)on a generator with a small 240v brushless motor driving
an exhaust fan on the same circuit as the welder in the hope that this will
prevent the new machine from joining the other dead ones!
To have these repaired by the "authorised repairer" seems to cost about the
same as a new machine and the repairers all seem to have the same fix for
each machine which is: "Have to replace the whole circuit board mate and
thats why it's so expensive".........
Now I am no electronics expert but have a limited knowledge of basic
circuitry so I opened them up and had a look inside......
All these machines appear to have blown power transistors and rectifiers on
the PC boards
In every case there is a power transistor which has virtually exploded.. so
I thought.... maybe I could source the individual component.... desolder and
replace with a new component and see what happens... being a $10.00 part, if
I do it in my own time I could salvage one for my own use.....Maybe??
BUT.....
In every unit the identifying numbers on the parts has been covered over
with some type of varnish or silicone material which is slightly translucent
but not enough to read the values of the component and when I have tried to
remove this stuff.. the damn numbers are removed with the stuff!!
I contacted Esab asking for a circuit diagram showing component values etc.
but they declined with the usual...."contact an authorised repairer for
replacement PC board" which wasn't much help at all!
So what I would like to as here is:
Can anyone give me any ideas of where to find the values of these
components?
or.....
Is there a possibility that due to the failure of the power transistors and
rectifiers on the PC board, is there a chance that lots of other bits in the
machines could be also damaged making a repair more expensive than just
buying a new machine? and if so... is there anything I can do with these
machines?
Any thoughts would be appreciated!
Thanks in advance
Gary....................
Bob
Bob
"Gary Slater" <GKA@"NOSPAM."bigpond.com> wrote in message
news:gRAca.833$dE2....@newsfeeds.bigpond.com...
Gary Coffman
>I have a few 240V - DC inverter welders which have I have salvaged from my
>workshop.
>
>I have:
>Esab LHN 140
>Esab LHO 150
>Miller Goldseal 140
>
>Each one of the above are dead machines which went "POP" and stopped working
>(words of my faithful employees) while being run from a generator on site
>jobs. I suspected the machines had problems with power spikes etc etc. ..
>from running on a generator which doesn't have real smooth power control /
>too small etc etc...
>
>I have got some advice from an electrician mate who suggested running a
>small inductance motor from the generator while using the welders to soak up
>these irregular "spikes" which I have arranged, and am now using a new
>machine (Gismi 140)on a generator with a small 240v brushless motor driving
>an exhaust fan on the same circuit as the welder in the hope that this will
>prevent the new machine from joining the other dead ones!
I'm afraid that's bad advice. If the problem is spikes in the power, then
shunting inductance across the line will only make it worse. What that
does is produce a first order high pass filter, which is exactly opposite
what you want. (Spikes are effectively high frequency components
because of the rapid risetime.)
What you need is a low pass filter. The way that's done is with inductance
in series with the lines, and a capacitance in shunt across the line. That's
the way surge suppressors are built, usually with the addition of varistors
in shunt across the lines as well to clip the largest voltage excursions.
Your best bet, if the problem is surge and spikes on the generator output,
is to buy an industrial surge suppressor box. This is just a bigger version
of the power strips sold to protect computers.
But the problem may be due to brownout. That's when the voltage sags
too far under load. An inverter will try to compensate for that by drawing
more current, which can blow the power transistors. The only real solution
to that problem is a bigger generator (or arrange for shore power).
>To have these repaired by the "authorised repairer" seems to cost about the
>same as a new machine and the repairers all seem to have the same fix for
>each machine which is: "Have to replace the whole circuit board mate and
>thats why it's so expensive".........
>
>Now I am no electronics expert but have a limited knowledge of basic
>circuitry so I opened them up and had a look inside......
>
>All these machines appear to have blown power transistors and rectifiers on
>the PC boards
>
>In every case there is a power transistor which has virtually exploded.. so
>I thought.... maybe I could source the individual component.... desolder and
>replace with a new component and see what happens... being a $10.00 part, if
>I do it in my own time I could salvage one for my own use.....Maybe??
>
>BUT.....
>
>In every unit the identifying numbers on the parts has been covered over
>with some type of varnish or silicone material which is slightly translucent
>but not enough to read the values of the component and when I have tried to
>remove this stuff.. the damn numbers are removed with the stuff!!
The coating that they put on the boards is intended to keep chips and
conductive dust from shorting out the welder's circuitry, also keeps fungus
from growing on the boards in tropical climates. But it also effectively
makes troubleshooting very difficult. Not only are parts values hard to
read, it is also hard to probe the boards and take circuit readings while
troubleshooting. The coating makes it very hard to unsolder bad parts
and solder in replacements without damaging the board too.
>I contacted Esab asking for a circuit diagram showing component values etc.
>but they declined with the usual...."contact an authorised repairer for
>replacement PC board" which wasn't much help at all!
That is infuriating, but all the welder manufacturers seem to want to
keep their designs a big secret. Of course they can't do that if the
person wanting to know is a competitor, since reverse engineering
isn't *that* hard. But for the guy who just wants to fix a broken machine
it poses a real problem.
>So what I would like to as here is:
>
>Can anyone give me any ideas of where to find the values of these
>components?
>
>or.....
>
>Is there a possibility that due to the failure of the power transistors and
>rectifiers on the PC board, is there a chance that lots of other bits in the
>machines could be also damaged making a repair more expensive than just
>buying a new machine? and if so... is there anything I can do with these
>machines?
The latter is almost certainly the case. Whenever the big power components
explode so spectacularly, you can count on some of the smaller more delicate
control components being shot too.
>Any thoughts would be appreciated!
Switch to conventional transformer machines. They are much more robust
against spikes, surges, and brownout than are inverters. Of course your
men don't want to hear that. They probably really like the small size and
low weight of the inverters. But if you want to keep using inverter machines,
you're going to need to better condition the power that you feed them. That
means bigger generators, constant voltage transformers, surge suppressors,
etc.
Gary
Rick
My plasma cutter just died due to, it appears, a line voltage drop. I
dropped it off at my local welding shop so they could send it out to the
"authorized" service center.
The bad news was not long in coming. They declared the circuit board
dead and the cost to repair was $750. Strange, I had an inverter machine
fixed last year and it was also the circuit board and THAT one also cost
$750! I am sure it is just a coincidence. Fortunately the machine was
repaired under warranty so I dodged that bullet but this one is still
ricocheting around.
But I digress. I did not go along with the repair on the plasma cutter
and started looking around. I found this outfit on the web:
I have not used them yet but they say they will repair that $750 board
for $159. It will be in the mail Monday morning.
Check them out and see if they can do you any good. I could not find
anyplace else to supply a board or repair the machine. It seems the
manufacturers have pretty well locked out most other avenues for us end
users to repair our machines.
Rick
tmi...@mdems.umaryland.edu
: >"Any thoughts would be appreciated!"
: http://www.welderboards.com/
: Rick
Be real careful. You may have other parts that are not on the board that
are bad. When you replace the board, the other bad parts could cause the
new repaired board to fail.
Tom
--
___________________________________________________________________
** Tom Miller **
E-mail tmi...@umaryland.edu
Gary Slater
Thankyou for the advice from all of you!
I think these dead machines will end up in the dead pile in the back shed
along with other various machines, drills, grinders rotary hammers etc
etc...
I'll be in the market for another new machine in the coming weeks and as
suggested by Gary Coffman my guys wont like the idea of dragging around a
Transformer machine so it will be another inverter. I will also look into
buying a decent generator (The amount of cash I have spent hiring these
cheapo gene's and the costs of the inverter machines they have killed to
date leaves serious consideration!), maybe with surge protection or some
type of control circuitry to minimise the problems described.
I would appreciate any suggestions from the group on what to choose for a
new inverter and generator. The machine would be used for stick welding only
si I don't need anything fancy, just heaps of grunt with the most rugged
construction and smallest / lightest unit possible (Don't want much do I?)
I am in Australia, so advice about products available locally would be in my
best interest!
Thanks again to all replies!
Regards....
Gary.............
"Gary Slater" <GKA@"NOSPAM."bigpond.com> wrote in message
news:gRAca.833$dE2....@newsfeeds.bigpond.com...
Ernie Leimkuhler
the "To," "Cc," and "Newsgroups" headers for details. ]]
You should see if you can find a dealer for Arcon Inverters.
They are built like tanks and intended for use from really bad
generators.
The guy who designs them is the original inventor of Inverter welders.
He founded Powcon originally.
In article <0YWca.1409$dE2....@newsfeeds.bigpond.com>, Gary Slater
cope
> [[ This message was both posted and mailed: see
> the "To," "Cc," and "Newsgroups" headers for details. ]]
>
>
> You should see if you can find a dealer for Arcon Inverters.
> They are built like tanks and intended for use from really bad
> generators.
>
> http://www.arconweld.com/
>
>
> The guy who designs them is the original inventor of Inverter welders.
> He founded Powcon originally.
>
into the Arcon machines. The basic TIG/stick machine runs $2500 w/o
wire feed. This isn't cheap, but if it lasts its worth the money. Do
you know of anyone who has used one of their units?
Ernie Leimkuhler
<abc...@swbell.net> wrote:
> Ernie Leimkuhler <er...@stagesmith.com> wrote in message
> news:<160320030120420216%er...@stagesmith.com>...
> > [[ This message was both posted and mailed: see
> > the "To," "Cc," and "Newsgroups" headers for details. ]]
> >
> >
> > You should see if you can find a dealer for Arcon Inverters.
> > They are built like tanks and intended for use from really bad
> > generators.
> >
> > http://www.arconweld.com/
> >
> >
> > The guy who designs them is the original inventor of Inverter welders.
> > He founded Powcon originally.
> >
> Ernie, I have a 1986 vintage PowCon 200SM w/wire feeder. I looked
> into the Arcon machines. The basic TIG/stick machine runs $2500 w/o
> wire feed. This isn't cheap, but if it lasts its worth the money. Do
> you know of anyone who has used one of their units?
I have yet to get any field reports about them.
I can't think of anyone I would trust more to design a great inverter
machine.
Keith Bowers
You might want to pose your question to these folks:
http://www.currenttechnology.com/engr_support.htm
They probably make the best surge/transient suppressors around. I had some
of their big industrial stuff installed in a computer facility several
years ago. Absorbers located on input and output of UPS building ( 2 320KW
Exide units) and on the output of each power center in the computing
facility. One evening we took a lightning strike between the UPS building
and switchgear. It took the guards several hours to clean the brown off the
walls 8o), but NOTHING got through to the computers. I had a Dranetz
transient recorder running at the time and it didn't even know there had
been a storm. Their sutff in neither cheap nor inexpensive, but if properly
installed it does work. They do make power strip size equipment too.
--
Keith Bowers - Thomasville, NC
Manfred W.
> Hi All,
>
> Thankyou for the advice from all of you!
>
> I think these dead machines will end up in the dead pile in the back shed
> along with other various machines, drills, grinders rotary hammers etc
> etc...
>
> I'll be in the market for another new machine in the coming weeks and as
> suggested by Gary Coffman my guys wont like the idea of dragging around a
> Transformer machine so it will be another inverter. I will also look into
> buying a decent generator (The amount of cash I have spent hiring these
> cheapo gene's and the costs of the inverter machines they have killed to
> date leaves serious consideration!), maybe with surge protection or some
> type of control circuitry to minimise the problems described.
>
> I would appreciate any suggestions from the group on what to choose for a
> new inverter and generator. The machine would be used for stick welding only
> si I don't need anything fancy, just heaps of grunt with the most rugged
> construction and smallest / lightest unit possible (Don't want much do I?)
>
> I am in Australia, so advice about products available locally would be in my
> best interest!
>
http://www.fronius.com/welding.technology/products/mmaw/tp1500.htm
You can buy them at: http://www.paulengland.com.au/fronius.htm
I highly recommend using a proper circuit breaker with correct current
rating and rather low overcurrent rating (magnetic trip). In this case
it would be 16A, I think.
For testing purposes when buying a new generator, I would use a heater
with about 3,5kW, switch it on and off at once and measure the voltage
of the generator. The lower the voltage after switching off the
heater, the better.
HTH
Manfred W.
