My soldering skills have been confined to splicing wires and replacing a diode. After reviewing Youtube tutorials, I've decided to attempt to replace a burnt out lcd on the climate control unit of my car. I purchased a cheap variable temp soldering station from Fry's and am now struggling to practice desoldering on a old mother board. The iron has a real fine pencil tip tinned with .032 rosin core solder. Initially, I was able to desolder a few joints but now am unable to. I'll clean and tin the tip and try again and again. One tutorial suggested adding fresh solder to a troublesome joint but I can't get it to melt. Supposedly, the station is a 70w unit with a 392f-897f range. I focused a infrared thermometer on the tip and for some reason it registered cold. I tested the iron against some wire and registered in the 140f range with the station turned up to the max..Tested a 25w pencil iron with roughly the same results. I don't know if I have a equipment or technique issue.
Thanks for any constructive suggestions.

 

I think your soldering iron has burned out. Take/send it back to Fry's.

 

If you press the bare solder end to the iron tip and it does not melt your iron is either set too low or has a problem.

See if you can exchange it.

 

I can tin the tip without issue but the moment I apply the tip to a soldered joint, nothing happens, it won't melt and neither will new solder dabbed on the joint.

 

I can tin the tip without issue but the moment I apply the tip to a soldered joint, nothing happens, it won't melt and neither will new solder dabbed on the joint.

Intermittent contact in the heater circuit. Return for exchange.

 

Motherboards are particularly difficult to solder and desolder because they have multiple layers that sink away the heat from your iron tip quickly. It's often necessary to use a preheater under the board. Your iron may not be working correctly but you chose a challenging practice medium.

 

Thank you KJ for your reply. I just picked up a 60w digital station from RadioShack and am still having no success no matter how high I set the temp. It is gratifying to know that the problem is probably my source of material rather than technique. Will a board out of a tv be easier to work with?

 

Probably. It depends on the construction and layout. By the way, an infrared thermometer will read very low when aimed at a reflective target so unless you can figure out a way to make flat black solder, it won't be useful there.

 

Probably. It depends on the construction and layout. By the way, an infrared thermometer will read very low when aimed at a reflective target so unless you can figure out a way to make flat black solder, it won't be useful there.

Or you adjust its emissivity value.. Most IR's have that setting for anything other than a perfect black body..

 

It is gratifying to know that the problem is probably my source of material rather than technique.

Its still a skill/technique that you just haven't acquired yet

 

Make sure you have a large enough tip and a good amount of solder to act as a thermal bridge to the lead/pad junction you're trying to heat.