Tenma soldering station not heating...

[shardian]

I got a Tenma 21-7935 soldering station off of ebay for cheap "as-is" hoping to save some cash. Well I set it up to test just now, and it won't heat. The machine lights up, the controls work, the led readout works, and the "read temp" is showing 77 degrees, so it appears to be working. Can anyone who has troubleshooted a soldering station point me in the right direction where to start? Am I just screwed/ heating element dead and unrepairable?

[shardian]

I disassembled the iron to see if anything jumped out at me. Are the iron heating elements prone to failure? The iron has probably seen better days, but I would prefer to know if the base unit is working before I order a new iron. Nothing really jumped out at me as being amiss inside the soldering iron. I supposed one of the insulated connectors could be broken. A new iron is only ~$10, so I guess I'll be out that either way huh?

So at this point, I'll let this thread simmer for a day or two to see if anyone recommends a decent test for the iron and the base unit.

[ChadTower]

Depends on the unit, really, but the heating element on a lot of them is a consumable part.  I'd contact the manufacturer or try to find a support forum for Tenma to be sure.

[shardian]

I sent an email to tenma Customer support.

[Ken Layton]

Tenma is a trademark for MCM Electronics' line of test equipment and tools.

I'd get a multimeter and set it to measure resistance. Unplug the iron from the base. Now connect the meter across the power cord of the iron and read the resistance. If no continuity then the cord or element are bad.

The heating element on my old Radio Shack/Ungar iron is 30 watts and the resistance reads about 300 ohms with my meter (which is correct for this brand/model of iron).

Heating elements do wear out or burn out as do the tips.

[shardian]

Tenma is a trademark for MCM Electronics' line of test equipment and tools.

I'd get a multimeter and set it to measure resistance. Unplug the iron from the base. Now connect the meter across the power cord of the iron and read the resistance. If no continuity then the cord or element are bad.

The heating element on my old Radio Shack/Ungar iron is 30 watts and the resistance reads about 300 ohms with my meter (which is correct for this brand/model of iron).

Heating elements do wear out or burn out as do the tips.

Cool. I'll take my DMM to work tommorrow and test it out. I'll have to figure out which pins are power and ground though, because this unit has several wires that go to the iron. some for power, ad some for the thermocouple leads. Shouldn't be too hard to figure out.

[shardian]

Well I didn't see any continuity between any set of wires in the iron. Doesn't really matter though because that thing wasn't going back together anyways once I was done with it.
I'll go ahead and order another one.

BTW, Tenma never returned my email.

[ChadTower]

Email customer service is always the slowest method... especially when your issue is "I bought a used X off ebay...".  You may as well tell them you found it in a dumpster.   

mcminone usually has strong deals on soldering equipment.

[Ken Layton]

MCM Electronics makes Tenma equipment.

[shardian]

MCM Electronics makes Tenma equipment.

I understand that.

Here is the link:
http://www.mcmconnect.com/tenma/product/21-7935/

The customer support linked on that page has not responded. Is that a little more clear?

[Ken Layton]

I have found as with most tech support problems it's best to telephone them rather than email.

[shardian]

They emailed back and said that almost every time it is the iron. I'll be ordering today.

[ChadTower]

That probably means your iron does not have a replaceable heating element.  Lower end ones are like that.

[wjgarner]

The tenma model 21-7935 soldering station problem mentioned has a fix. First unscrew item 7, then remove the tip (7), then slide off the metal split slleve on 6. Notice the barrel of 6 is black. Take a file and file off this black coating and steel wool it shiny. Repalce all parts, turn on the iron, and the temperature will go to where you set it and not stay at 77 degrees

Bill Garner