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Subject: Ungar 9900 Soldering Iron Base Station

Complaint: Dead

Diagnosis: Secondary on power transformer is open

Reason: Shit tier QA at factory didn't notice a wire strand bridged across the power transformer output.

Hard to believe they missed that, it's one of the strands from the power transformer's wire. I can't fix it as-is, it will need a replacement transformer or an external transformer. Can't use DC because this particular model uses a light dimmer-like circuit (Triac) to control the heater of the iron.

Subject: Ungar 9900 Soldering Iron Base Station Complaint: Dead Diagnosis: Secondary on power transformer is open Reason: Shit tier QA at factory didn't notice a wire strand bridged across the power transformer output. Hard to believe they missed that, it's one of the strands from the power transformer's wire. I can't fix it as-is, it will need a replacement transformer or an external transformer. Can't use DC because this particular model uses a light dimmer-like circuit (Triac) to control the heater of the iron.

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[–] • 2 pts (edited )

It's actually a customer unit, but it's mine now because they didn't want it.

As far as I know, this hasn't worked for years. I have no idea why the secondary burnt before this little piece of wire did, as it's a 2A transformer. Looks like an old oil burner power transformer, which is what it probably started life as, and was repurposed by Ungar. Could have been the transformer was defective from the start and this did it in. All I know is the secondary is now open and this piece of wire was there.

I'm planning on trying to find a transformer at the next show I go to, maybe I'll even get lucky and find an old lighting transformer that's high current AC. The tip is seized in the sleeve, but that should be just a matter of soaking it in some blaster and getting it free.

(I also don't know if there was more wire here at one point and it fell off as it burnt away. The joint isn't in the best of shape to start with.)

[–] • 2 pts

The tip is seized in the sleeve, but that should be just a matter of soaking it in some blaster and getting it free.

Word of caution on the tip removal (no jew joke intended). The tip has a "D" shaped shaft that goes down into the sleeve and makes contact with a fragile ceramic heating element. The element is about an inch long and just a couple of millimeters thick so it isn't very resilient. These heating elements are nearly impossible to get hold of these days, so treat it delicately if you remove it. Also might want to clean the PB Blaster off of it before heating it up should you get the unit running again.

[–] • 3 pts

(no jew joke intended)

And yet I laughed

[–] • 1 pt

The sleeve and the tip on this one come off as one piece from the heater assembly, that's what I'm going to soak. https://pic8.co/sh/XeWhia.jpg

[–] • 1 pt

Ah, I see. I think that uses the cylindrical heating element instead of the flat rectangular one in my UTC-290. You might have a better chance of finding that kind as a replacement since Weller continued on with that style after they bought Ungar. The flat ones are pretty much extinct now, unfortunately for me.

[–] [deleted] • 1 pt

Well you could always rewind the transformer. I've done that a few times for various tube amps. But those are generally pretty big transformers.

[–] • 1 pt

24VAC transformers should be easy to get, they're essentially furnace power transformers. I don't mind making a wall wart to run the thing.