TB 302 (dc only unit) Help!!

[K&D welding]

Hello all,
I just got my used TB 302 DC only unit. It welds great, on the run idle setting it will "idle up" when I strike the ark and will hold the idle up for a few seconds after I am done welding...... NOw If I plug something into the generator side and the unit is in the idle run setting, it will not kick up and produces low power, but if I manually turn it to the run setting it idles up and I have all the power I need, Any suggestions on where to look for what part is in need of repair

Thanks
D

[cruizer]

Idle pickup toroid has failed and needs to be replaced

[M J Mauer]

Welcome to the forum K&D welding.

[K&D welding]

Thanks Cruz,
I will looking in to it,

[K&D welding]

Cruz is that the same as a current transducer? Sorry for the slew of questions I am new to fixing. Also finding part numbers seems a bit of a pain, I think the PN is #168829
thanks again

[cruizer]

Yes, CT1

[duaneb55]

I suggest you check it before just replacing it. CTs can but rarely fail.

You haven't offered a unit SN but you should have 0VAC at CT1 leads (PC2 RC11 pins 1 & 3) with no auxiliary load and around 3.6VAC with a 100W light bulb load.

If CT1 checks out then you've got a PC2 board problem.

[K&D welding]

sorry the SN is LH300258Q, I hope its a quick fix, I am ok with just turning it to run and than back to idle run when I don't need full power but I really want the machine to be 100% functional.
thank again

[duaneb55]

Use the values I posted previously to check CT1.

Also check the harness connectors at PC1 (RC21) and PC2 (RC16) for poor/corroded connections.

[cruizer]

You should get 66 ohms on a resistance test

[duaneb55]

That too.

Thanks cruiser.

[K&D welding]

Ok, SO I had the cover off today, Turns out I don't have my muliti-meter. So I can not report on any of the checks that you told me to do ( hope to get one). But I did see that slip rings look like they could be dressed, The have dark streaks in them and I could only see about and 1/8 or so of carbon left on the brushes, The unit has 2600 hrs on it and it looks like it never really had any maintenance done to it. I didn't notice any power problems (other than not kicking up when in idle/run on the generator side). I was welding 1/4 jet rod with it a also plugged my 211 on the 220 side and welded all day.

Being that I just bought it, I just want a solid base line and 100% working machine
thanks
D

[Kpack]

I would sure use a stone on the slip rings and put new brushes on it.

[cruizer]

I would sure use a stone on the slip rings and put new brushes on it.

Actually if you use a fine grit emery, sprayed with brake clean, that's best. No reason to change out the brush cartridge. Might only show an 1/8", but they are spring loaded and thats all that shows out of the cartridge

[Kpack]

Cruzier I thought 2600 hrs was a lot on a set of brushes. So you like Emory cloth and brake cleaner better than a commutator stone ?