Grant -- Lincoln TIG welder trouble -- no HF

As it turns out, the PC board that controls HF is fine. There is 115 volts coming into the inputs of the HF system. Then, per schematic, it
goes through a big resistor and feeds a high voltage transformer.
What I know is that 110v comes into the HF system, but nothing happens in the HF circuit after the transformer.
However, one more observation is that out of maybe 50 times I turned on the HF system, about two times there was arcing between output wires from the high voltage transformer, coming into chokes, and something near that area (it was a little hard to see). But during all other tries, there was no visible arcing.
i
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Ignoramus19289 wrote:

Sounds like you need to pull that HV/HF board for closer observation, stuff shouldn't be arcing on a PCB.
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It is not on a PCB, this is a high voltage assembly with what I think are chokes mounted on top of a HV capacitor.
i
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Ignoramus19289 wrote:

HV arcing on those leads would seem to mean one of two things - failing or damaged insulation, or the HV running excessively high due to a lack of a load to hold it down. Careful inspection of the wires, connections and components downstream are in order I think.
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I agree, especially with the second part of your sentence (high voltage due to lack of load).
i
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On Tue, 21 Jul 2009 20:59:38 -0500, Ignoramus19289

Your mantra for tomorrow: "Ohm... Ohm... Ohm's Law..." :-P
--<< Bruce >>--
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"Bruce L. Bergman" wrote:

Ohm, Ohm on the range
Where the Volts and Amps play...
--
You can't have a sense of humor, if you have no sense!

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Ignoramus19289 wrote:

Corona arcing. Gotta clean it up!
--Winston
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Winston wrote:

http://www.repairfaq.org/samnew/tvfaq/tvaffpv.htm
--Winston
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You might not have the voltage regulator - the arc points/metal bars that regulate the voltage to a distance voltage or breakdown voltage.
If a above it can break down insulation and it can feedback into the circuit that might shut down in protection of itself and the rest of the system.
Martin
Ignoramus19289 wrote:

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This is, indeed, the case.

I do not see any such protection.
What I observe is that whenever the control pedal is depressed, there is 110v as input to the HF circuit. 95% of time there is no output (no sparking in the spark gap, no HF) from the HF circuit, and 5% of time there are some arcs where output from the high voltage transformer goes into the chokes.
Any sort of protection would disable the observed 110v input.
i

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Model? JR Dweller in the cellar
On Tue, 21 Jul 2009 20:11:02 -0500, Ignoramus19289

-------------------------------------------------------------- Home Page: http://www.seanet.com/~jasonrnorth If you're not the lead dog, the view never changes Doubt yourself, and the real world will eat you alive The world doesn't revolve around you, it revolves around me No skeletons in the closet; just decomposing corpses -------------------------------------------------------------- Dependence is Vulnerability: -------------------------------------------------------------- "Open the Pod Bay Doors please, Hal" "I'm sorry, Dave, I'm afraid I can't do that.."
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On Jul 22, 11:11 am, Ignoramus19289 <ignoramus19...@NOSPAM. 19289.invalid> wrote:

Have you got a schematic, and can you post it to the dropbox? - Andrew VK3BFA.
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On Jul 22, 11:11 am, Ignoramus19289 <ignoramus19...@NOSPAM. 19289.invalid> wrote:

I answered my own question re the manual (yep, gee I am getting good) - and looking at the crappy schematic, it says there should be 204 volts going into the cold end of the HF transformer - you may be correct, as we don't have the changing line voltages routine here.
I would check the output voltages on the 2 zener diodes on the RHS of the arc control PCB - should be 24v and 10v, also C106 near them - its a pretty basic power supply, and its a good place to start.If they are not correct, or low, then check the connection of the auxiliary transformer. Fault finding is progressive elimination of possibilities, and rule no 1 is Check the power supply rule no 2 is See rule no 1.
Andrew VK3BFA.
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It is not 204 volts, it is wire numbered (labeled) 204.
The volts is about 115.
Schematic does, indeed, leave much to be desired.

Well, as far as Miller or Hobart welders go, their HF circuits get 115 volts as input, so I would suppose that the input voltage is what it should be.
i
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