dialarc 250 hf intermittent high freq operation

[Greg T]

Hello, I am having Intermittent problems with the high freq on start mode,
the high freq works properly in the continuous mode. according to the
wiring schematic the CR1 relay should energize to start the high freq, I
have opened the machine and checked the voltage at the relay coil when I hit
the torch trigger and have 37 volts DC at the coil. Does anyone know what
the coil voltage should be ? could the problem be the variable resistor R3.
Any help will be greatly appreciated

[cope]

Greg, I see you got here. I just posted a reply at Google. I guarantee quicker response than over there.

[matt]

Hi Greg
The relay should be a 12 volt d/c and you are correct the R-3 controls that set voltage. Do you have the serial number of the machine in question. Can you tell if the relay is coming in? The contacts on the relay could be defective. If you have the serial and a fax number I will get you a cir. dia..
Thank you
Matt

[Greg T]

Matt, thanks for the reply, the S/N is "HH083168" the fax is 602 229 5830. I have checked the circuit again and the CR1 coil is definitley receiving 37V DC. the relay does not energise and the contact arm moves freely. I can manualy push in the relay and the high freq starts. I have yet to isotate the coil and ohm it out, the 37 volts has me a bit puzzled because i have not touched the variable resistor.

Thank you

Greg T

[Al T.]

At times I have worked with circuits that apply +voltage to the relay coil and the switching circuit applies ground to the other side. You can tell if the relay is energized if there is a higher voltage on one side and a low on the other. Also the coil would be magnetised when on.

I hope this info helps you.

[matt]

Hi Greg
I did fax the cir dia with voltage checks on it. If you didn't get it let me know.
matt

[Greg T]

Matt, I have the fax. thankyou very much I will continue troubleshooting tonight and update this post with my results.

Again

Thanks

Greg T

[Greg T]

Matt, well the high freq on start is up and running, the Cr1 relay
coil was open. soldered in a new relay saturday and everything is great.

Cope, Thank You for bringing me to this site

Matt, the information you provided me was invaluable, Thanks so very much.

Al, Thanks for the info!

This is a great site, Thanks Hobart

[cope]

Greg, you are welcome. I think this is the best welding forum on the net, bar none. Google has some good people but the delay to read your post and answers is intolerable to me.