Old L-Tec welder with a 60Hz hum while welding DC-

Date 01-19-2010 02:53

Check for any loose fastners inside, or rod stubs, etc. that may be vibrating along with the magnetic field. If You can't find anything wrong, don't worry about it.

By Lawrence (*****)

Date 01-19-2010 06:21

Not the High Freq running when it shouldn't??

Open the hood and take a look at the points while its welding.

By ssbn727 (*****)

Date 01-19-2010 09:44 Edited 01-19-2010 09:53

I would first rule out the possibility of phase imbalance if it's 3 phase machine... Then look into what Larry mentioned first by doing what he suggests, and check all of the connections and switches also, and then if the buzz sound is still there then...

Sounds like one of the SCR's on your main bridge rectifier circuit but, also check if there's a zener diode in the circuit or the varistor (and any other resistors in the circuit too) also to see if they're not up to snuff going on you too... Those older L Tech's used to make those sounds when I had to replace them soon enough... What's the model and year of this machine? What type of output current and voltage are you getting when the machine is on? are your reading coming pretty close to what they should be from how you're setting the parameters on your power source?

The only way to properly diagnose this type of equipment is to start from the primary input power source, then go follow the current & voltages as it goes through the changing circuitry via the power source schematic so that you don't overlook anything downstream

Respectfully,
Henry

By MMyers

Date 01-19-2010 14:05

Filter caps? If they're aluminum electrolytics, they probably need to be replaced if they're anything like the electrolytics found in consumer products.

By ssbn727 (*****)

Date 01-19-2010 17:34 Edited 01-19-2010 18:34

Hi Mike!

That is a possibility but, unless we're given more information on this power source like a schematic posted, model number and/or serial number of this specific power source as well as what type of power source Ray is even talking about, then we could all drive ourselves crazy guessing for naught!!! :) :) :)

Hey Ray? Could you please give us some more specifics on this old L-Tec power source and if possible, could you post up a schematic of the power source so we could troubleshoot which circuit would interact in such a manner to enable the AC balance control to influence the intensity of the hum...

By doing so, we could then see if there's a component that's normally closed to prevent that from occurring which obviously is now open so that one can effectively alter the intensity of the hum via either increasing or decreasing the resistance, or voltage, or current on that specific circuit which may be one of many, many circuits which make up the power source electronics.

So there's something that has obviously failed for this to occur... The only thing that's left is to isolate the component, or components that are malfunctioning which is the cause of the problem and replace it! Btw, Ray! You didn't answer my question regarding whether or not you're getting the output you should be getting with respect to the power source setting you have chosen to weld with... Could you tell us what your output current is while welding, and is it within reason what you set your power source to?

Respectfully,
Henry

By MMyers

Date 01-19-2010 17:41

I'm with ya Henry, schems are a necessary tool when diagnosing electrical problems, especially hum because there are about 8 bagazillion causes for it and usually only one or two solutions.

By Kix

Date 01-19-2010 15:39

See if this gives you guys anymore ideas? Again, while running DC- on stainless, I can change the HUM of the arc by adjusting the A/C balance. Keep the good info coming guys!

By Lawrence (*****)

Date 01-19-2010 16:50

You just went over my head with the latest description Ray.

I bet that clue means something to Henry...! He will Sherlock Holmes it if anybody can.

Good to see you around.. Been missing your inputs lately.

Lar

By ssbn727 (*****)

Date 01-19-2010 16:55

Again! what is the model number of this machine? Is it a CC power source? Is it a transformer/rectifier? An inverter type power source? Can you post up the schematic of this power source? I ask this because we can guess until we all turn blue, but don't you want to find out what's wrong with this power source, or are you doing this to us as a practical joke of some sort?

I'm almost sure that you want to find out the problem but, if you don't furnish more information on the specific power source, it just makes it almost impossible to figure out what could be the root cause of your problem.

Respectfully,
Henry

By fbrieden (***)

Date 01-19-2010 19:07

It hum's because it doesn't know the words!

By ssbn727 (*****)

Date 01-19-2010 20:51

What a "Hummer!!! :) :) :)" Hubba, hubba, hubba, hubba, hubba!!! :) :) :)

Respectfully,
Henry

By Kix

Date 01-20-2010 11:48

LMAO!!!

By Kix

Date 01-20-2010 11:54

It's an L-Tec 306 Heliarc. And yes, Heliarc is the model name. Yes, It's a CC power source. As for a transformer/rectifier, I'd have to say yes again. I really do want to find out if this is normal. The A/C balance knob tells you to put on max pen for DC-. This being said, I think this is just the nature of the beast and that it's a big POS. Here's a link to a picture of the POS. ;-) http://www.dmsf.ust.hk/emfmm/ltechtig.html

By rodofgod (**)

Date 01-20-2010 21:36

Hi All!

Kix,

http://www.esabna.com/literature/Archive/Manual/F14-001%20-%20F14-999/F14-447_Heliarc-350_AC-DC.pdf

This manual seems to be applicable for your machine if made before April 1995!

You could try getting it to sing a tune it knows, then it wouldn't have to hum!!

Regards