How do you get diodes loose

[Guest]

How do you remove the diodes from the PCB without burning it up. I have been fooling around with this igniter box I have that didn't work. I heated the tip of the wires from the plug and got them loose from the PCB. But when I tried the diodes I had to hold the soldering iron on so long it started to burn the PCB. So I tried the butane torch, thought the high heat might melt the solder real fast and I could pop the diodes right off. THIS WAS A VERY BAD IDEA. PCB caught fire. Lucky I had a beer close at hand to put it out. Hate to wast beer, I thought I would just ask if anybody else has replaced diodes and stuff on a PCB from an igniter.

 

[tkent02]

Try a solder sucker.

 

[posplayr]

Try a solder sucker.

sound more like he should put the butane tourch down and slowly step away from the work bench. Stop wasting the beer.:-\\\

 

[koolaid_kid]

Mike, you probably need to make a choice: work on PCB or drink beer. Doing both may lead to less than perfect decisions.

Thanks for the chuckle, it made my morning brighter.
And I agree with tkent02, try a solder sucker next time. I use a solder wick, which does pretty much the same thing.
You may find that the legs are bent just a bit which may explain why it was difficult to remove the diodes.

 

[Guest]

solder sucker?

solder sucker?

I have never heard of a solder sucker. So what I did next, is opened my vice wide enough I could lay the PCB on there and have room to reach under with my tiny needle nose pliers. Took hold of the wire on the diode pulled down, but not real hard. Carefully touched the tip of the Hot iron to the diode wire sticking through the solder. Even with the wire bent it slipped right out leaving a small clean hole. I think I,m going to sharpen one of my soldering iron tips to a nice small point just for this kind of job. I only had to touch the Iron to the diode wire for a second and it popped loose no burning. Had to be careful not to spread the solder around on the PCB.
FOOTNOTE: DO NOT USE CARB CLEANER TO TRY AND TAKE THE PLASTIC COATING OFF THE PCB. It just makes it a sticky mess. It don't need to come off.

 

[Steve]

Welcome to SOLDERING 102.


Too bad you skipped SOLDERING 101.


As you have noticed, it does not take much, when done correctly,
but it's real easy to make a mess of it if you just charge in blindly. :-\\\

.

 

[Dogma]

Solder sucker.

Lousy picture at Radio Shack's site. It's basically a syringe spring-loaded to suck (just like Congress). Quality on this one is a bit variable. Worse than most stuff at HF. Check for smooth, fast action before leaving the store. The squeeze-bulb version is impossibly awkward to actually use. Avoid.

George, I tried the wick, years ago. (Hacking a 1541 floppy drive, I think it was.) I didn't like it. It does work, but it's slow. I think it would be very useful for removing excess solder (bridges, etc.), but not so much for component removal. (Like a 40-pin DIP socket, what a job!)

+1 on the bent legs. Make sure the solder is melted, then hold the heat on the joint while pulling, twisting, whatever, with pliers. Cut 'em off first if you have to. But be sure the solder is liquid when you pull. You don't want to accidentally lift the trace off the board.

 

[Guest]

No problem

No problem

I already destroyed the trace with the butane torch. At least now if the one on my bike go's bad I can work on it without the damage. I want to make one out of the HEI Modules from a car. For a spare. Do you really need a sucker? Once I got the hang of it, they came out pretty clean.

 

[Dogma]

I already destroyed the trace with the butane torch. At least now if the one on my bike go's bad I can work on it without the damage. I want to make one out of the HEI Modules from a car. For a spare. Do you really need a sucker? Once I got the hang of it, they came out pretty clean.

If you can get the component out one lead at a time, you can get by without solder removal, as you found. You may find that you want to get the solder out of the hole before trying to install the new component though. If you bend the leads around too much, they break, or worse, fatigue and break later. As usual, the thing can be done, just easier and more reliable with the tools.

 

[posplayr]

There was probably nothing wrong with the diode in the first place, most all failures of older electrics with large through hole parts is PCB trace fatigue.

Normally re flowing all of the solder traces and solder joints brings back 75-85% of old PCB's assuming you also replace all Electrolytic capacitors.

If you succeeded in lighting the board on fire, I would now suspect any of the trace bonds in that area and would carefully inspect and run stranded jumper wires (point to point) if there is any doubt in the traces adhering to a charred fiberglass.

A smaller soldering iron will help alot in trying to do this. You have to be careful about putting too much heat into both the board and the components. So a smaller guage (e.g. 18-20 ga) is all you typically would need.