Newbie Question: Filing Down Component Leads

Good morning, all! While technically minded, I am brand new to repairing PC Bs. I'd therefore greatly appreciate relatively simple explanations and you r indulgence of my ignorance.

I recently obtained a Geiger counter which was in need of being rebuilt. Be cause it was manufactured in 1962, the components are large and provide me with plenty of working room. After desoldering all components, I took a loc ksmith's file (very small and fine) and took off just the immediate outer l ayer of the leads of the components. My intention was to remove existing so lder and any other "gunk". As soon as I began to see the copper color of th e lead showing through, I stopped and moved on to the next. After doing thi s for all components, I soldered them back in and everything is working per fectly...for now.

I ran across some information AFTER doing this that tells me that might hav e been a bad idea. Are component leads coated with something protective tha t I should have left on? Should I expect earlier-than-usual failure from an y of my components since I filed off this outer layer? Any insight is much appreciated.

Thanks a ton!

Kindly,

Matthew Connor

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Matthew Connor
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Most component leads are tinned. That is the copper wire is coated with a thin layer of solder. This makes it easier for soldering. Copper will oxidise very fast, so don't scrape the tinned wires to bare copper. It will not hirt anything,but just make soldering more difficult. When repairing circuits use some 60/40 solder with rosin core flux. That is unless you run across some of the newer lead free stuff. You might alos want to get a bottle of the liquid flux to use. Just make sure the flux is for electronic work. There is some acid flux that is made mainly for plumming. It will tend to draw moisture out of the air and corrode the copper in electronics.

If you think there is a lot of crud on the wires, use one of the Scotch Bright typw pads to just shine them up, but not enought to remove the old solder. It is often recommended to tin the bare copper wires before soldering them.

I doubt you will get any failure because you scraped off the coating.

Reply to
Ralph Mowery

You can get RA flux (rosin, activated) in solder or in a bottle. It cleans off oxidized leads very well. Kester 44 solder is RA, and you can get the same stuff as Kester 1544 (only in gallons or pails unfortunately). However, MG Chemicals 835 RA flux is available from Digikey or Amazon in much smaller quantities for about 10 bucks. I use a small bottle with a stainless steel needle.

When the needle clogs up (as it will), just touch it with the iron and it magically clears out.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
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Phil Hobbs

PCBs. I'd therefore greatly appreciate relatively simple explanations and y our indulgence of my ignorance.

Because it was manufactured in 1962, the components are large and provide m e with plenty of working room. After desoldering all components, I took a l ocksmith's file (very small and fine) and took off just the immediate outer layer of the leads of the components. My intention was to remove existing solder and any other "gunk". As soon as I began to see the copper color of the lead showing through, I stopped and moved on to the next. After doing t his for all components, I soldered them back in and everything is working p erfectly...for now.

ave been a bad idea. Are component leads coated with something protective t hat I should have left on? Should I expect earlier-than-usual failure from any of my components since I filed off this outer layer? Any insight is muc h appreciated.

A lot of work for probably no real reason. If the solder wetted properly o n the leads, then no further action is required. Occasionally you'll run i nto a component lead that defies soldering. Normally, cranking the heat on the soldering station and adding some flux will crack the oxidation and th e solder will flow out.

Reply to
John-Del

This is Usenet. There are no simple explanations.

Rebuilt? Mechanically, electronically, or both? Maker and model number? For 1962, my guess(tm) would be a bright yellow Lionel CD-V700m. You might also want to look into modifications:

If it's what I think it is, the PCB is made from phenolic (paper). Phenolic boards do NOT tolerate much heat, soldering, bending, etc. In other words, the traces fall off and the board delaminates or crumbles. Your desoldering may have trashed the PCB.

Some counters were coated with some kind of conformal coating in order to protect the high voltage that runs the GM tube. You should not have removed it and will probably need to reapply it to the high voltage components and PCB. Phenolic is hygroscopic (absorbs moisture) and will need to be heated for a while to evaporate moisture before it can be coated. Personally, I think you just ruined it. It might be easier to just make a replacement G10/FR4 PCB. You can also add your additional shock mounting more easily. There may also be a market for your unused boards. Check the Yahoo Geiger Counter groups (there are several) for advice on this:

The best of intentions will probably lead to a trashed counter. I suggest that you stop and thing this over before blundering forward.

Open the counter and just breath onto the PCB. That puts a thin layer of moisture on everything. If it continues to operate normally, you win. If it craps out and recovers when the moisture evaporates, you'll need to deal with replacing the coating that you removed.

We seem to do things in much the same way. I always read the instructions after I get into trouble. It's more fun that way, but does have the disadvantage of destroying things if I miss something.

Tinning, which prevent the underlying copper from oxidizing and turning into green crud. Also, the conformal coating to prevent condensation from shorting out the hi-v section.

No. They're fine. After all, the counter was probably designed to survive a nuclear attack.

Good luck.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

I've had old copper wires (In some old insulation.. zip cord type stuff) and it gets and oxide/ coating/ something/ that flux doesn't attack very well.

I end up having to first scrap it with sand paper or a green scrubbie. (Scotch brite) and then tin it.

I've always wondered what the tenacious oxide is.

George H.

Reply to
ggherold

I don't know. It seems to be some sort of organic crud iirc.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Phil Hobbs

Good morning, Jeff! Thank you so much for your insight. My counter is a Lio nel CD V-700 Model 6b, manufacture date 1962.

On one hand, I'm a little confused. You mentioned several times different v ariations of me having likely "trashed" my counter by doing what I did. At the very end however, when I asked if I had done any harm, you said, "No. They're fine. After all, the counter was probably designed to survive a nu clear attack." So I'm not quite sure that I'm understanding if what I did w as bad or not.

On the other hand, you have given me lots of details to consider and sugges tions in areas I haven't even started to think about. You've obviously got a great deal of experience and I'll be taking all of your suggestions into account as I move forward with my project. I'll be trying the breath moistu re thing right away. Thanks for taking the time to educate an east coast ne wbie! :) -Matthew

Reply to
Matthew Connor

Dr. Hobbs: Thank you very much for your insight, sir! It's greatly appreciated! -Matthew

Reply to
Matthew Connor

Ralph, good morning! Thanks a ton for your input! I'm appreciative! -Matthew

Reply to
Matthew Connor

Just 'Phil' to colleagues. The fancy sig block is for SEO purposes. (It works great btw.)

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

That's the same as what I have. Watch out for leaky D cell batteries. I nearly destroyed mine when Duracell's leaked.

I would say it was a bad thing to tear it apart. You didn't mention if it was working before you attacked, so I question whether any of the work you've done was worthwhile or productive. If it was dirty, just clean the board. There's no reason to clean the component leads, or make it pretty unless you're installing a clear case and using it for show and tell.

The detrimental parts are:

  1. The phenolic PCB is very sensitive to handling, soldering, and "cleaning". You could easily have ruined it.
  2. The coatings that you removed are there to prevent the high voltage power supply from being shorted by water condensation and high humidity. By removing the coating (probably some type of conformal coating), you have removed that protection. However, not all C V-700-6b counters had coated PCB's. One of mine does, while the other does not.
  3. Some of the old components are difficult to find, such as the neon regulator tube, but are at least available. Unsoldering these and is a bit of a risk.
  4. The rotary switch is a big of a reliability problem. If you bend the contacts more than once, they'll break.

The good news is that the device is very simple and has few components. It's made for easy repair, which is fairly easy. That's the origin of my bad joke about the counter surviving a nuclear attack.

Drivel: It's not really a counter, because it doesn't count, but I can't get out of the habit of calling it a counter.

The breath test is fairly simple and will usually indicate immediately if you have a problem. I haven't tried it on mine for a long time, but as I recall, one counter consistently failed when I took it out a cold garage, and brought it into a warm house. With moisture all over the counter, it didn't work until it warmed up. This is a rather severe test and I would not expect even a conformally coated PCB to survive a condensed moisture test. However, a simple breath test should give you a clue as to how sensitive the counter is to moisture. If you want to fix that, some wax based conformal coating around where the GM tube cable connects to the PCB should be a good start. The wax coatings are nice because they come off easily if you need to do some rework. Make sure the PCB is clean and degreased before coating or you will trap the moisture under the wax.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

I'm not sure if you're talking about the same stuff, but the organic crud I've encountered on old wires I've interpreted as being plasticizer from the PVC insulation -- the same sort of stuff that coats the insides of car windshields in the summer.

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Norman Yarvin                                   http://yarchive.net/blog
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norman.yarvin

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