Desoldering Resistors

jheu02

AK Subscriber
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Are there any tricks I haven't tried?

I'm speaking of the ones with the leads bent towards themselves, almost like a staple looks. Though I use a desolder pump (handheld PE metal style) and desolder wick with extra flux, I'm still finding it difficult to remove the last bits of solder holding the bent leads to the pads, Thus, when I think I've done enough (trying to not overheat the pad and cause problems) there's still a tiny bit of solder holding the lead to it, and as I try to wiggle the component side lead (while heating) the pads are getting torn/lifted sometimes. It's only a couple it's happened to, but a couple more than I want to have happen to.

I've got scads of quality resistors I want to use during refurbs, but I've stopped as it's not worth the risk of lifting old pads.

I have no problems desoldering other components as long as the leads aren't tightly bent like the resistors seem to be.

Anything I'm not doing, or just give it more time and more wick?
 
A good desoldering pump and fresh solder will make all the difference. Heat and apply a tiny bit of fresh solder before you desolder- everytime. Make sure the pump is in the ideal position to really pull the solder away from the lead and 99% will go up the pump. The last part that can hold down that bent-over lead can be got by using very fine flush cutters between the bent-over lead and the land. Carefully just squeeze a little and the bent over lead will release and the land will never be damaged. You can also use the flush cutters to then straighten up the lead and then push it out.

If you are replacing them, why not just cut them on the component side first and then desolder and pull the short cut-off lead out?
 
If the component won't be reinstalled, it's often best to clip it away on top, then remove the leads from the bottom. Another trick is to heat the joint, then wiggle the part while it cools, so the lead doesn't reattach. Don't be afraid to apply flux- things go better with flux. FWIW, only the large size Soldapullt pump, DS017, (or a desoldering station) work well. The smaller size pumps just create problems.
 
here's my .02¢

Sometimes I can get under the bent lead with the chisel tip of the iron, using a slight rotating motion to straighten the lead while the solder is liquid. Or, alternatively (if the lead is tight to the pad), solder iron in one hand and a very small, flat blade screwdriver in the other hand, rotating the free end of the lead up from the pad. Once the lead is twisted away from the pad the last bit of solder is more easily accessible with wick.
 
Actually if you can afford it, get a microspade lug tip. then you put the sharp part of it under the wire and just pull it up. gotta know what your doing here and actually, believe it ro not, NOT remove all the solder you can. What is left conducts the heat.

Learning how to solder I got these words :

GET YOUR BRAIN IN TO THE CONDUCTION OF HEAT

And really, on alot of old boards you might be better off just using nodlenees pliers and pulling the lead out the top as you heat it on the bottom. If it leaves a hole you are lucky, if not use the solderwick. Get Chemwick, it is the best. Well it was. the NTE stuff i s giving me pretty good results these days because none of the suppliers we deal with have Chemwick.

Another thing I have to say - Don't use a vacuum desoldering station on a one sidedd board. It is worse than solderwick, almost anything. It will suck the foil right off of there if it is old and weak.

We don't want that.
 
JURB makes a very good point on single sided boards. A lot of old ARC stuff has no plated through holes, and the pads will come off if you so much as look at them sideways. A modern double sided board is pretty rugged by comparison.

At the risk of inciting laughter and derision, I'll tell you what one of the big test equipment makers said about repairs. Can't remember if it was HP, Fluke or somebody else- To avoid damage to the PCB, clip the leads close to the component body on top of the board and solder the new part to the old leads. Yep, on the highest grade of test equipment, that was an accepted procedure. My guess is they were also ones who bent the leads over, mil style.
 
Sometimes you have to add solder to the joint before desoldering, to get the solder to flow, especially if you are working on lead free soldered boards. If you apply leaded solder to the lead free solder, it will lower the melting point of the solder, allowing easier removal. I do not recommend using solder suckers on pc boards, you can damage the pads. It is safer and gentler to use only solder wick. A trick I use is to snag the end of the component lead in the solder wick and gently pull, while heating, to lift the end of the lead. The only safe solder sucker I have found is a $300 Hakko solder removal tool.
 
If the component won't be reinstalled, it's often best to clip it away on top, then remove the leads from the bottom. Another trick is to heat the joint, then wiggle the part while it cools, so the lead doesn't reattach.

Sometimes you have to add solder to the joint before desoldering, to get the solder to flow, especially if you are working on lead free soldered boards. If you apply leaded solder to the lead free solder, it will lower the melting point of the solder, allowing easier removal. I do not recommend using solder suckers on pc boards, you can damage the pads. It is safer and gentler to use only solder wick. A trick I use is to snag the end of the component lead in the solder wick and gently pull, while heating, to lift the end of the lead. The only safe solder sucker I have found is a $300 Hakko solder removal tool.

All good information.

I use solder wick for removing small quantities of solder, and a small spring loaded solder sucker for large amounts until it becomes manageable with wick. I have never had problems using the small solder sucker warned about by other posters here.

Adding just a very little solder to help it flow is very good advice. When you have nearly all the solder off, and the lead won't budge, try applying just enough heat to melt the solder and wiggle the lead. (as per Conrad again). This has the effect of cracking the joint, then you can clip off the lead and remove the component. For the toughest ones Conrad's suggestion of clipping off the leads on the top-side works well.

Whatever you do, apply the heat to the component lead not the pad - do not press the soldering iron onto the pad - guaranteed disaster. :yes:

I am definitely NOT a fan of using the soldering iron tip as a "hot screwdriver". :no:

Correctly executed soldering and de-soldering is a pet subject of mine :)
 
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Lots of good suggestions. I haven't tried the adding solder to desolder and hadn't thought about clipping from the top because i always throw them into a used parts bin for if I run across something i need it for. But this is what I'll try next. I'm just wanting to replace some of the carbon films with metal films in the audio path and then also use new when rebuilding the power supplies and other high heat areas. So, since it wasn't replacement of failed parts, I didn't want to proceed any further. The way Pioneer bent them tight to the board really makes it a pain to remove them.

Thanks all.
 
For parts that I just cant get the last bit of Solder I use the reverse of the de-soldering iron. I cover everything with a little masking tape but the part I'm removing. I put on the gloves and goggles. I get my can of air duster. Heat the solder till I can see it wants to move then blast it with the air while still holding the heat to it. 99.99% of the time all solder will be removed and the part is free to be lifted off.

It does make a mess with solder bits so you have to isolate the part well. I will use masking tape and sheets of paper to completely isolate the part. I have on occasion had to use a stronger aluminum tape because the parts are close together and the masking tape burns. When using the aluminum tape I am very carful when removing it.

2nd option I use is an inferred heat gun with concentrating tip. Heat just the part until solder is fluid and use tweezers to remove the part.

I either case you will need to then clean the board with flux and solder braid.
 
I use all desoldering ways mentioned above if it suits me......(edit....except Pcbmann his way, he was posting same time, I will have to try that one also! )

Some crocodile clips having good springs (like the stainless steel Hirschmann ones) can aggressively grab component leads if you can not reach a component using pliers.
This in case if you want to go the pull from top/heat on the bottom way as Jurb describes.
 
I too have tried all the above. I found rocking a component as the worst thing to cause a solder pad damage. For really "stapled" leads I'll use an exacto fine sharp tip and get under the leads and straighten them a tad.

For resistors I made a little pry bar out of a cheapie small paring knife that was easy to bend into shape if I can't get plyers on it. Also handy to test a resistor to lift a leg.
 
If the component won't be reinstalled, it's often best to clip it away on top, then remove the leads from the bottom. Another trick is to heat the joint, then wiggle the part while it cools, so the lead doesn't reattach. Don't be afraid to apply flux- things go better with flux. FWIW, only the large size Soldapullt pump, DS017, (or a desoldering station) work well. The smaller size pumps just create problems.

Yes, this is the best way.

Definitely the way to go. Clip out the lead, get in with flush cutting snips and cut as close to the board as you can get, un-solder and remove as much of the solder as you can with a good solder sucker (Rat Shack's aluminium one is actually pretty good for this) and then heat and remove it from the solder side of the board. Replacement resistors are typically dirt cheap.

Sometimes, if the bent in portion of the lead is long enough, after using the solder sucker you can snip the bent in portion flush (or nearly so) with good flush cutting snips to make removal from the component side easier.

Sometimes you can snip the leads near the component grab the remains with needle nose, heat the pad and maneuver the lead inward to allow the bent in portion to slide out.

They all work, sometimes.

Good Luck

Shelly_D
 
Lots of good suggestions. I haven't tried the adding solder to desolder and hadn't thought about clipping from the top because i always throw them into a used parts bin for if I run across something i need it for. But this is what I'll try next. I'm just wanting to replace some of the carbon films with metal films in the audio path and then also use new when rebuilding the power supplies and other high heat areas. So, since it wasn't replacement of failed parts, I didn't want to proceed any further. The way Pioneer bent them tight to the board really makes it a pain to remove them.

Thanks all.

The first rule of soldering is to have a good physical connection. I can see the benefit of replacing caps. Unless the resistors are used in high-current circuits, I doubt they change value that much.
 
I too have tried all the above. I found rocking a component as the worst thing to cause a solder pad damage. For really "stapled" leads I'll use an exacto fine sharp tip and get under the leads and straighten them a tad.

For resistors I made a little pry bar out of a cheapie small paring knife that was easy to bend into shape if I can't get plyers on it. Also handy to test a resistor to lift a leg.

You have to be sure the solder is melted, and stays that way while you are rocking the component, and be very gentle when you do this, otherwise as you say - a great way to lift tracks.
 
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The first rule of soldering is to have a good physical connection. I can see the benefit of replacing caps. Unless the resistors are used in high-current circuits, I doubt they change value that much.

Please let's not get off topic. This is a very good thread that is revealing some useful information seldom discussed at this type of depth.

Many people replace CF resistors with MF in some positions, not because of value drift, but because several other parameters of MF, (i.e. temperature coefficient) are significantly superior. Another topic for another thread :D
 
......

I am definitely NOT a fan of using the soldering iron tip as a "hot screwdriver". :no:

Correctly executed soldering and de-soldering is a pet subject of mine :)

Perhaps my previous explanation leaves something to be desired. :scratch2:

But I believe the method I attempted to describe is safe and, when done correctly, results in a minimum of heat stress to the PCB. It reduces the number of passes that may be needed with wick, or other methods, to get at the last bit of solder between a bent-over lead and the solder pad.

Straightening the lead a little can be quick and easy. When the solder is liquid, a twist of the wrist. A quick heat up while simultaneously applying a small mount of upward pressure to the lead.

If the lead is bent to a 45° angle, the chisel tip can do it. It is not necessary to press the tip into the pad. If the lead is bent further, or flush with the board, then the tip of a tiny screwdriver, or blade of an X-Acto knife can get under the lead when the solder is liquid.
 
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With solder sucker iron rest tip on the bend in the lead for a sec then squeeze bulb couple times. Making sure it's hot get the end wire into the sucker tip and carefully straighten it up and one last off center suck. maybe possibly.
 
Maybe drifting OT, but remember that soldering iron tips are usually complex multi-layered iron plated things, and should never be used to apply physical force if you want them to last. That said, when the going gets tough, just close your eyes and ignore the grunting and scraping noises coming from my bench. :yikes:
 
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