Syncwave 250 HF help

[turbo_b]

Guys,

I need some help with my Syncrowave 250. Its a 2000 model with low hours on it.

Earlier this week it was working fine. Tonight I went out to weld some aluminum, set the output to AC and the HF to continuous, stepped on the pedal and got nothing.

Switched over to DC and HF start, but HF start didn't work. It will hold an arc when scratch started.

Dressed the tungsten HF electrodes and reset the gap at 0.008in. Now I can get momentary HF but it won't stay on.

Exercised the HF strength knob a few times but didn't help so I pulled the covers and blew the machine out with compressed air.

If I wait 30 seconds the HF circuit will run for about 5 seconds and then dwindle out. Let the pedal up and wait 30 seconds and get 5 more seconds of HF.

Nothing inside the machine "looks" wrong, there was only minor dust build up in the machine, hardly enough to blow out.

Thoughts or suggestions on how to get the HF working again?

Thanks,
-Rob

[turbo_b]

Nobody has any suggestions?

I am questioning the HF capacitor. Anybody know how to test its function?

[MMW]

Have you checked the preflow setting? One time it got moved on mine & wouldn't start an arc until after the set time. Took awhile to realize it.

[MMW]

I assume you checked all the connections, especially the ground/work clamp?

[turbo_b]

Thank you for taking the time to reply. Unfortunately I don't even get HF at the HF points.

I have also checked that the breaker isn't tripped for the 110V circuit.

[cruizer]

And what would that serial # be.....

Jusr cause you say its a 2000 there is a problem with the 2001 units...

[turbo_b]

Thanks Cruizer,

This is a LA219533, there is a sticker on the back side of the front panel that reads "TESTED BY TIG #AUG 04 2000".

[turbo_b]

Tonight I checked for voltage input to the HF coil, I have 118v when stepping on the pedal and 5.x v when off the pedal. This seems to indicate that the control circuit isn't fried.

I have read that I can't check the output of the HF coil without a special meter so I didn't try.

I read a post on the interwebs by somebody who said they were a Miller tech, the post said that if you disconnected the HF capacitor you should get a 3000v spark but it wouldn't be enough to weld with. I tried that but still no HF at the points.

Any thoughts?

[cruizer]

Ocillator Capacitor or more likely secondary side of the HF transformer is pooched.

[turbo_b]

Followup post - Turns out that the fiberglass board that the tungsten points are screwed to inside the welder absorbed some moisture. the points were shorting into the fiberglass board!

My 1975 Miller Econotwin had a ceramic board that I swapped out for the Syncrowaves fiberglass- problem solved!