Componant Replacement Technique

[W9ZSL]

Yo!  I have a very early Hallicrafters S-40.  No doubt because it has an 80 rectifier and does not have a PM speaker.  It belongs to a friend of mine and I rebuilt an old TRF Zenith for him a few years ago but replacing componants was easy.  There weren't many to begin with so this is going to be my first real challenge.  Desoldering everything is out of the question me thinks so I'm guessing old caps and resistors should simply be clipped out and leave just enough of the old leads behind so a new componant can be "grafted" in it's place or am I wrong?  What technique is best?  Once I'm finished with this radio I plan on restoration of a Gonset G-33 which was my first receiver back in the stone age.  Just buzz me at W9ZSL@yahoo.com and may tubes rule forever!!!! .

[AF9J]

That's what I do.  I did it with my Viking II, the HP-23A power supply I used with my old Heathkit Cheyenne, and the Yaesu FTdx-401B (which is kind of an oddball rig, since it uses 6KD6 sweeptubes, and has AM capability [about 35 or 40 watts of carrier], along with SSB & CW capability), I'm restoring at the present time.  Unless it's a PC board mounted part, or you want to make it look pretty, it's just easier to clip and leave enough lead behind, to solder the new component to, than trying to desolder stuff from turrets, that has twisted together wires, and tons of solder.  Besides, with all of the heat you'd subject the other components (that you don't want to replace) to. just to get rid of enough solder, to remove the component you want to replace, IMO, you run the risk of heat damage to other components at the joint you're de-soldering.

[Opcom]

Unless the customer wanted otherwise, I usually clipped off the leads an formed 3-4 turns on the new part's lead, slipped io over the old lead and crimped, soldered. That was much faster and less costly to the customer than painstakingly cleaning off the lugs removing all traces of the old parts, and doing it the perfect way. For all but the most sensitive circuits there's nothing wrong with that.

[aa5wg]

I disagree.  Make a clean look rather than the clip, snip and solder look.
Chuck

[KC4VWU]

I will have to say both ways have their good points.

I once recapped a HQ-129X and found that the original cap leads were not unmercifully wrapped and twisted half a dozen times around the terminals they were soldered to, so I removed each one and soldered the new ones in. The sets that you do find such practice in are probably best done the other way. Just make sure you clean the remaining lead with a little scotchbrite or sandpaper before soldering the new part to it.

The reason for using the pigtail technique is to keep from breaking a fragile, or worse yet, unobtanium part. Either way, it's a major PITA to have to repair something that didn't need it in the first place. Been there, done that. It also usually ends up with muttering the phrase '" Aw D@mn, that was STUPID! Why did I do that?"

Good luck and mainly, have fun doing it! If it's NOT fun, it's WORK!

73, Phil

[ke7trp]

Clip off the old part flush at the terminal.  Take new part and grip the lead with needle nose pliers so an inch is sticking out past the plier.  Heat the terminal and wiggle the new parts lead through, wrap new lead around tight, Then solder.

Even very "busy" terminals still have room for one more lead to go through.  I like a good Mechanical connection BEFORE solder.



C

[k4kyv]

 I like a good Mechanical connection BEFORE solder.

It depends on how the connection is made.  You only need a good enough mechanical connection to positively hold the wire(s) into place while the joint is being manipulated before solder is applied. You don't want to make such a firm mechanical connection that it will be impossible to unsolder any of the wires without overheating components, burning insulation off adjacent wiring or breaking the lug. I don't know how many times I have CURSED the person who assembled a piece of equipment because they insisted on wrapping the wire through the hole and tying it in a knot through the lug, making it totally impossible to de-solder without major damage.

I usually just make a hook at the end of the wire, poke it through the hole, and crimp the bend with needle nose pliers.  That is enough to make it stay in place while other wires are inserted into the same hole and the wire is moved around if necessary.  If solder is properly applied and everything is clean enough to fully take solder, the soldered connection will outlast the wire even if the wire is yanked, pulled or bent back and forth many times.  If it is necessary to unsolder, apply a  little heat, jiggle the wire, and it should unhook and pull right out before anything is damaged.

The worst has to be WW2 command sets and some Collins equipment.  I have seen instances where they literally passed the wire through the hole, out, around the lug and back through the hole again and again and again, until several turns of wire are literally wrapped round the lug and through the hole. To remove a wire from the lug entirely, you have to literally carve it out in pieces. Arrrgh!!

[K5WLF]

 I like a good Mechanical connection BEFORE solder.

I have seen instances where they literally passed the wire through the hole, out, around the lug and back through the hole again and again and again, until several turns of wire are literally wrapped round the lug and through the hole. To remove a wire from the lug entirely, you have to literally carve it out in pieces. Arrrgh!!

I've run across that a few times. Worst I found was in a Berlant-Concertone tape unit. Some previous owner had outboarded the power supplies for the channel R/P amps (fairly nicely done actually) and I needed to re-build them into the amps to make room for a mixer in the 19" road case. The connections back into the amps were of the Gordian Knot variety and nearly banjaxxed the terminal strips a few times. Royal PITA.

Like Don says, bend them around and crimp to hold until the solder gets there and you're good. They'll live forever. No need to overdo it.

ldb

[ke7trp]

Yes. I put the lead through. Bend it around, Reach in with my small snips, Snip the lead off short and solder it.  I like to have at least a hook and wrap like Don is talking about before solder.

I found the SX42 was "braided" in and out of the terminals.  I guess that Gal was board in 1952.

C

[N8ETQ]

 Yo'

     Lot's of good points and technique brought up in this thread.

       Quite often both methods may be used in the same rig. Depends
on the original joint. My usual approach is to remove the original component
(This is our Goal) by clipping the leads close to the body of the component.
This leaves a "workable" lead length to accomidate either scenerio and
provides a visual confirmation of where it came from. One component at
a time. I try to get as much solder off the lug as I can with Solder Wik
and before it really cools if you wiggle the lead enough as it cools you can
often just push it through enough to, as  Don says "carve it out in pieces".
Cold solder joints just peel off with needle nose pliers. Double wrapped
Mil Spec stuff is differnt but were talking about an S40 now. I think you'll
find it easy to get the old lead out completly.  If it wont "Give" just "Squeg"
the new component on the long lead you left. Either way it ends up, you
have a good replacement that will stand up to the rigors and G-forces
antique Ham equipment is subjected to now adays!

      I just did an S40-B for Bill DBN type, and it came out nice. I was
impressed with it's prefomance after and the 12ma drop in HV current
draw don't hurt.  See pix.  Slap a 3 wire cord on that thing and Enjoy!

     Just like anything in life, You can make it as hard to acomplish as you
want.  We are talking about re-capping an S40 right?

73 es GL

/Dan

[KA0HCP]

I mostly use the Squeg technique.   It's fast, neat, mechanically strong, and as compact as the original.  Plus I haven't damaged any adjacent components or solder points!!!   I use a pin vise for wrapping the leads.

[KC4VWU]

Small needle nose pliers and the smallest of those little "precision screwdrivers" that can be found everywhere works pretty well too. Once you form the coiled end on the replacement part and slide it over the pigtail lead, you give it a squeeze with the needle nose pliers for a good mechanical bond; then solder.

If it were more toward a higher end receiver, it would be a totally remove and replace only procedure. Maybe even a re-stuff depending on what it was.

I do like the way the yellow poly and 'chicklet' mylars un-clutter the chassis underside though.

73, Phil

[WQ9E]

If the lead will come out easily and cleanly I will remove it, otherwise I clip and replace.  If it isn't obvious visually it will be obvious once you try to remove the first part whether the leads will be difficult to remove.  It is way too easy to damage another component with too much force and heat and sometimes damage isn't obvious until later (like a broken connection inside an IF transformer after too much heat/force is exerted on the terminal).

Radio and TV News had an excerpt from an Air Force "white paper" about soldering in one of the early 50s issues.  The AF conclusion was that, except in rare cases, there was no need to make a connection mechanically solid before soldering and unless necessary it shouldn't be done because of potential damage when future repairs were needed.  The authors concluded that modern solder did not require a mechanically secure connection and such connections could also mask a cold solder joint.  The exception was for heavy components and transmitter output tank components were cited as an example of the class of part that needed to be mechanically solid before mounting.

[Rob K2CU]

It really depends on what kind of repair work you are doing. If it is a single component in non sensitive section, then the best bet is the snip the lead at the body of the old part and use the grafting technique. The old lead will provide a good thermal isolation from the rest of the components. AS stated above, sometimes it is best to just cut off the lead close to the lug and heat the lug just enough to poke in the new part's lead into the solder. This is tricky and can leave you with a cold solder joint if the part moves even a little bit during cooling. and there is a lot of solder to cool with jittery hands holding the lead.

When doing a major restoration, as in replacing a slew of carbon comps and oil/paper leaded caps, you might consider this for removing the leads from a lug on either a tube socket, switch wafer contact, or twist  lock cap. OF course, if replacing/rebuilding the twist lock cap, then just snip and remove the twist lock cap, etc.  The switch wafer contacts are not only easy to damage, but replacing a single contact itself becomes a major project. I save all old wafer sections I can find just form this eventuality, or for adding contacts when doing a modification.  Old tube sockets with missing or broken pins are another source of replacement pins if you damage one in you project radio.

Anyway, I use a Radio Shack desoldering tool along with a Weller soldering gun. The Radio Shack tool consists of a modified pencil iron of fairly low wattage, perhaps 40W. It has a special hollow point tip with a long metal tube that has a rubber squeeze ball attached. Normally, say on a PCB, you heat up the tool Squeeze the bulb, and then place the hollow tip over the PCB lead to be unsoldered. When the solder liquifies, you release the bulb and the solder is sucked into the head of the tip.  Then the toll is placed over a safe surface and the bulb squeezed repeatedly to expell the collected solder. The tool works well, is cheap, and has replaceable tips. You have to be careful not to burn the tips by having it lie around while plugged in. Anyway, for chassis solder lug applications, this iron does not get hot enough to quickly desolder a large solder filled lug. So I use the Weller to heat and melt the solder with the RS solder sucker at the ready to suck out the solder when it gets liquified. You can usually do this quickly enough to not damage other components. The, I use small sharp diagonal cutters to cut the component lead loops where they wrap around the lug.  You can use this for just one lead if need be. BY cutting the wrap loop it becomes a snap to get the rest of the component lead out of the lug. Other wise you may overstress the lug and possibly break it off while wiggling/pulling on the lead. Just be sure to remove the short wire lead debris first so it doesn't become FOD inside the radio. After the new component(s) is/are installed, just resolder with the gun.

I have also used solder wick, but it is costly and there is a lot of solder to suck out of that lug. Solder wick is best for surface mount rework.

[w3jn]

The Quigg technique is by far the fastest, easiest, and does the least damage.  Some don't like the appearance of this, though (Hi, Carl!).

As some have noted trying to remove a component lead completely from a tube socket or terminal strip can be difficult indeed - and can often lead to damage to the terminal and/or other components.  Me -being lazy and not wanting to repair damage I use the quigg method, by just coiling 3-4 turns of the new component lead around a paperclip that's held in a pin vise.

[KM1H]

Yep, some of those methods are disgusting and remind me of the type of job the old Radio/TV shops used to turn out. The tech was a farmer before WW2 or Korea, carried a rifle for 4 years and then read a few library books to become an instant tech. If he got a ham license he was the model for Hammy Hambone

As mentioned its not hard to do it correct in most sets. Start off with cutting the leads with about 1/2" remaining. Use a mechanical solder sucker and/or Solder-Wik and remove as much of the solder as you can and exposing the wires. Jiggle the wire while the joint is molten and see if you can spot the end and then poke it free with a Solder Aide or even a sharp awl and pull out from whichever side is easier. If its buried then poke a hole thru the mess with the above tool. Put the new component in with a 90* bend to hold in place while soldering. Any more wrapping is a waste of time as a good solder joint wont even come loose in mobile service unless JN is driving thru an Athens riot

Since the S-40 series is one of the easiest to work on show a little pride in your workmanship, after the first few you will find it takes less time than Hammy methods.

I refuse to buy Hammy Hambone messes but got stuck with one from a guy on here and wound up redoing it all...it even had true Hammy mistakes and wrong components.

End of rant.

Carl
 

[The Slab Bacon]

I usually use a mixture of all of the above.

If you can easily unsolder and remove the component, I will.

If you can heat the tie point and poke a hole in the terminal with a soldering aid tool, I will.

If the tie point is chocked full of schtuff, I will nip off the old component lead and use the quigg method.

I am kind of anal about neat wiring and neat lead dress, so I add the extra blob of solder for the quigg type repairs as kind of the last resort.

A quick trick when unsoldering leads from terminals or tie points is to first nip the wire off close to the old component. Then heat the tie point and give the nipped wire gentle a wiggle with a pair of needle nosed pliers as it's cooling. this will form up a nasty looking cold solder joint at the tie point. Then look at it very closely, and take a pair of mini nippers and carefully trim off the pieces of the old wire that is wrapped around the tie point and wiggle them free. Eventually you will prune away all of the old component's lead and have room in the hole for the new one. Carefully wrap the new lead through the hole, then apply heat and some new solder. The heat and the resin from the new solder will flow the cold solder nicely and you're good to go. this may sound like a lot of work, but after a little practice you'll find that it only takes a few minutes per joint.

[k4kyv]

What exactly is the Squeg technique?

I think you may be talking about leaving a fraction of an inch of the old component lead in place as sort of an anchor post, then forming a spiral of wire with the new component lead by wrapping it round a small diameter rod like the blade of a tiny jeweller's screwdriver, then slipping the spiralled wire over the old wire, like a sleeve. Then you crimp the spiral (if the fit is not already tight) and apply solder.

I have used that technique many times.  It beats trying to completely unsolder a  cluttered terminal lug without damaging anything with heat or misdirected diagonal cutters. Done carefully, it looks neat and professional, and will hold up as well as the original.

[W1ATR]

Yeah you pretty much have it right Don. The original "Squig's" used to come from Sprague in a little blue box usually supplied with an order of caps. They were a small coil of pre-tinned wire and about a 1/2" in length with an I.D. approximate to the average component lead gauge. Cut out the bad part, slip a Squig on the remaining lead, slip the new parts lead into the other end of the squig, squeeze it up and put a little slobber on it and it was done.

Made for a quick in and out service call for the old TV repair guys.

Used to have a shoe box full of them I picked up from an old tv repair shop that closed.

[K9PNP]

I have done it both ways.  Also have messed up an unobtanium part or two.  Have found that a common round toothpick will work well for putting a hole in a solder lug, terminal strip, etc after you heat up the solder blob.  Nice thing is the solder won't stick to it when you leave it there until the solder cools.  Works for me, anyway.

[Ed/KB1HYS]

I swear by the squig (quig?) method.  At one time I even made tools to form the coils on components. A simple handle of wood, and two pieces of piano wire or wire nails.  A few turns around the wire and viola!   
I made them after attempting to repair some lab equipment where the wires where knotted through the terminal strips and I just couldn't get them out, and then had trouble getting another good solder joint. It was almost as if the old solder and the new were not compatible. 

Anyway, since I don't do museum restorations, I don't mind the looks, and frankly they're not that bad, besides mostly being hidden under a chassis anyway.  Gives a good mechanical and electrical joint.

[w5gw]

I'd prefer to desolder in 99% of the cases.  Why, because sometimes the component is not bad and might need to be reinstalled.  Also, it looks better.

One should invest in a desoldering gun that has a vacuum pump.  They are life savers.  Also a good selection of desoldering wick sizes.  Finally, a good magnifying light.
 
In 1% of the cases I'll opt to graft to bad component leads, but only when I suspect I'll incur damage to the tube socket lug or other components by trying to remove it at the soldered junction.

[Opcom]

The reason for using the pigtail technique is to keep from breaking a fragile, or worse yet, unobtanium part.

73, Phil

I respect Chuck's disagreement, but the above has generally been the reason for my preference. Some of the entertainment and general coverage receivers as opposed to communications equipment do not have the benefit of the best technology tube sockets and terminal strips.

[WQ9E]

Keep in mind that it is generally pretty easy to replace an individual tube socket contact rather than the entire tube socket.  In receivers with a large number of tubes you can often find an unused socket pin to steal from elsewhere in the receiver.   

I have been helping an old timer repair a DX-40 over the phone and after he described spending a couple of hours replacing a socket because of a broken contact I almost hated to tell him how easy it is to replace a single contact but I thought he should know for future reference.  Loctal sockets seem to have the most fragile contacts.

Switch contacts are a place where I very rarely de-solder a component unless it clearly will come out quickly and easily.  Switches are fragile and although it is possible to replace individual contacts it isn't easy like tube sockets.  Too much heat will also cause problems with contact tension leading to future intermittent problems and if you really overdo it with heat you can carbonize dust/debris on the wafer leading to fun with voltage breakdown between contacts.

[N8ETQ]

   You Bet!  This "Damage something Else" thing is kind of
overblown IMHO. Leaving leaky coupling/bypass caps in is
going to eventually Bite you. There are so many options
between "Elmers conductive Glue" and the "600W American
Beauty" Iron. Just gotta think outside the box.

    Thats the cool thing about this list. All options are
viable and could/should be used. There is no "One size fits
All" approach. Desired v. Practical technique depends on the
joint in question.

/Dan 

Keep in mind that it is generally pretty easy to replace an individual tube socket contact rather than the entire tube socket.  In receivers with a large number of tubes you can often find an unused socket pin to steal from elsewhere in the receiver.   

I have been helping an old timer repair a DX-40 over the phone and after he described spending a couple of hours replacing a socket because of a broken contact I almost hated to tell him how easy it is to replace a single contact but I thought he should know for future reference.  Loctal sockets seem to have the most fragile contacts.

Switch contacts are a place where I very rarely de-solder a component unless it clearly will come out quickly and easily.  Switches are fragile and although it is possible to replace individual contacts it isn't easy like tube sockets.  Too much heat will also cause problems with contact tension leading to future intermittent problems and if you really overdo it with heat you can carbonize dust/debris on the wafer leading to fun with voltage breakdown between contacts.