potentiometer case soldering (cadmium difficulties)

[hewo]

I polished the housing canopy so solder wets nicely.
But flitz musical polish obstructs wetting altogether.
I cleaned residual flitz using dry safety swabs, turns black from oxide burnishing.
But the super clean mirrored landing refuses to wet nicely using 60/40 tin lead legacy rosin cored.
If the canopy is scraped by razor blade, wetting historically accomplished.
Don't know why the polish method of surface preparation fails altogether.
Please explain remedy, gotta wet the canopy (strat elex bay overhaul.

[tedmich]

You can't remove surface contamination (polish) with just a dry swab IME, try citrus based de-greaser (goo gone) or maybe lacquer thinner. Also adding just rosin first to clean metal can help solder flow.

[The Dude]

Flux is your friend.

[Mick Bailey]

The polish intentionally leaves behind a protective film. This film also inhibits soldering, despite the metal looking clean and polished.

Some pot cases are tinned, some zinc plated. Cadmium has been prohibited for decades. Zinc has poor soldering qualities. The key to success is a mechanically cleaned surface (I use a glass-fibre pencil or blade) and a hot, thermally controlled iron or solder station. You need to complete the joint before the rest of the pot gets too hot. The flux percentage and type varies a lot - some are more aggressive and better wetting than others. Flux intended for electronic work is activated by temperature; if the soldering iron isn't hot enough, or doesn't have sufficient thermal capacity, then the solder won't wet the surface and flow smoothly.

[hewo]

carbide burr cleanse resolves

The polish intentionally leaves behind a protective film. This film also inhibits soldering, despite the metal looking clean and polished.

Some pot cases are tinned, some zinc plated. Cadmium has been prohibited for decades. Zinc has poor soldering qualities. The key to success is a mechanically cleaned surface (I use a glass-fibre pencil or blade) and a hot, thermally controlled iron or solder station. You need to complete the joint before the rest of the pot gets too hot. The flux percentage and type varies a lot - some are more aggressive and better wetting than others. Flux intended for electronic work is activated by temperature; if the soldering iron isn't hot enough, or doesn't have sufficient thermal capacity, then the solder won't wet the surface and flow smoothly.

Wow, nothing works!
Tried acetone swab cleanse.
Tried flux modern cleanse.
So carbide burred landings chewing housing to steel.
Then absolute success wetting and at low temperature.
Areas unwet but burred will rust in time exposed to atmosphere vapor.

[J M Fahey]

1) scratch zinc plated surface until you see shiny bright silver *steel* below.
Use box cutter tip / sandpaper / emery cloth / sharp screwdriver tip / wirebrush / rotary rasp / mounted stone / carbide burr / etc.

2) use 40 or 60W soldering iron

3) heat well area to be soldered and melt solder at the junction solder tip/pot case

4) since you scratched only a tiny area (5 x 5 mm or so) , solder will cover it in full, so don't worry about possible oxidation.
Besides, molten flux will cover and protect a few mm around the actual soldered area, so .....
And if it *really* worries you, wipe flux clean with an acetone or isopropyl alcohol or lighter fluid impregnated cloth and cover free metal with transparent nail polish.

5) please try to write in English, the common variety used by most.

[hewo]

The trauma of carbide burr debris contamination is real.
Take captivation debris intent, else particulates will enter into peripheral circuit exposed.
Simplest approach simultaneous capture generated debris by concurrent vacuum hood collections.
In my case, the underside of the strat pickguard loaded with complete circuitry intact.
No different than dental debris generation with concurrent suction debris collection.

[hewo]

1) scratch zinc plated surface until you see shiny bright silver *steel* below.
Use box cutter tip / sandpaper / emery cloth / sharp screwdriver tip / wirebrush / rotary rasp / mounted stone / carbide burr / etc.

2) use 40 or 60W soldering iron

3) heat well area to be soldered and melt solder at the junction solder tip/pot case

4) since you scratched only a tiny area (5 x 5 mm or so) , solder will cover it in full, so don't worry about possible oxidation.
Besides, molten flux will cover and protect a few mm around the actual soldered area, so .....
And if it *really* worries you, wipe flux clean with an acetone or isopropyl alcohol or lighter fluid impregnated cloth and cover free metal with transparent nail polish.

5) please try to write in English, the common variety used by most.

The video shows fender women soldering pot housing ground wiring but without surface prep as we discuss this thread.
This means factory soldering has capability "different" from our approach, or are factory pots tinned on their housing?

[tedmich]

the trick of soldering to a ring terminal mounted on pot bushing is a good one and doesn't lock everything together as much as "iron cross" grounding all the pots together.
http://www.te.com/commerce/DocumentD...ocLang=English

$0.19 each at Digikey
34115 TE Connectivity AMP Connectors | Connectors, Interconnects | DigiKey
These 3/8" ID ring terminals work very well and the ground wire can be both crimped and soldered.

[J M Fahey]

The video shows fender women soldering pot housing ground wiring but without surface prep as we discuss this thread.
This means factory soldering has capability "different" from our approach, or are factory pots tinned on their housing?

Answering in reverse order for better clarity:

b) no, factory pots use the exact same plating as ours.
Or to be more precise, there is not such a thing as "factory pots" .
Huge manufacturers make them by the tens of Millions for large Industrial customers, a few thousand are pulled from the huge batches and sold to Distributors for servicing and hobbyist use.
No reason, specially no Economic one, to make a separate substandard line just for us.

a) "factory soldering has capability "different" from our approach" ?

* sort of, if you want to see it that way.

* maybe "we" don't use the proper tools.

Not that they are not available, far from that, but modern hobbyists don't use them, many even ignore their existence or think they obsolete ... far from that.

Modern idea of what an average soldering iron should be (I'm talking the plain iron, not a soldering station):


with the tip being something like:

mind you this is a relatively large 40W type, most use the general purpose needle tip, because it's fine for ICs , LEDs, signal transistors, etc. and yet solders well power supply radial cap leads, TO3/TO247 legs, switch and pot legs, etc.

But is not enough to heat zinc plated surfaces hot enough for molten flux to "etch" the surface, reduce oxides and facilitate wetting, a most important factor in soldering, because the thermal mass of all but the tiniest metallic parts cools it below that critical temperature ... so you may be forced to *mechanical* surface cleaning.

This is what Fender amp builders used (by the way, there was nothing else) and which I also used in the late 60's, the old style 100W soldering iron, with a pinky finger thick bare copper surface ( which we tinned ) and thick flat sided surfaces:


look at the tip:


pity I can't put these side by side for a better comparison, anyway it's easy to see the way larger contact surface from this flat tip compared to the ubiquitous round one, but the main point is that it's not only a *temperature* problem but a thermal mass and contact surface one.

Another difference is that the old tips were tinned (with our own solder) over bare copper , excellent heat transmission, while modern so called "ceramic" ones are actually iron clad .

Easy to test, just pick them from the table with a magnet, but iron is a very poor conductor relative to copper.

So you can easily solder the old Fender way, both pot bodies and direct to chassis , with an old style 100W iron.

Just remember they are too large and hot for PCBs and, most annoying, copper dissolves quickly in solder, so in a short time they show a "caries" just where you need it most.

I used to buy copper bar by the meter and made my own tips, courtesy of a hacksaw and a bench grinder.

For the real macho jobs (soldering transformer legs and large electrolytic clamps to chassis) they used:

150W of pure (thermal) glory

[hewo]

maybe fender uses argon shroud?

Answering in reverse order for better clarity:

b) no, factory pots use the exact same plating as ours.
Or to be more precise, there is not such a thing as "factory pots" .
Huge manufacturers make them by the tens of Millions for large Industrial customers, a few thousand are pulled from the huge batches and sold to Distributors for servicing and hobbyist use.
No reason, specially no Economic one, to make a separate substandard line just for us.

a) "factory soldering has capability "different" from our approach" ?

* sort of, if you want to see it that way.

* maybe "we" don't use the proper tools.

Not that they are not available, far from that, but modern hobbyists don't use them, many even ignore their existence or think they obsolete ... far from that.

Modern idea of what an average soldering iron should be (I'm talking the plain iron, not a soldering station):


with the tip being something like:

mind you this is a relatively large 40W type, most use the general purpose needle tip, because it's fine for ICs , LEDs, signal transistors, etc. and yet solders well power supply radial cap leads, TO3/TO247 legs, switch and pot legs, etc.

But is not enough to heat zinc plated surfaces hot enough for molten flux to "etch" the surface, reduce oxides and facilitate wetting, a most important factor in soldering, because the thermal mass of all but the tiniest metallic parts cools it below that critical temperature ... so you may be forced to *mechanical* surface cleaning.

This is what Fender amp builders used (by the way, there was nothing else) and which I also used in the late 60's, the old style 100W soldering iron, with a pinky finger thick bare copper surface ( which we tinned ) and thick flat sided surfaces:


look at the tip:


pity I can't put these side by side for a better comparison, anyway it's easy to see the way larger contact surface from this flat tip compared to the ubiquitous round one, but the main point is that it's not only a *temperature* problem but a thermal mass and contact surface one.

Another difference is that the old tips were tinned (with our own solder) over bare copper , excellent heat transmission, while modern so called "ceramic" ones are actually iron clad .

Easy to test, just pick them from the table with a magnet, but iron is a very poor conductor relative to copper.

So you can easily solder the old Fender way, both pot bodies and direct to chassis , with an old style 100W iron.

Just remember they are too large and hot for PCBs and, most annoying, copper dissolves quickly in solder, so in a short time they show a "caries" just where you need it most.

I used to buy copper bar by the meter and made my own tips, courtesy of a hacksaw and a bench grinder.

For the real macho jobs (soldering transformer legs and large electrolytic clamps to chassis) they used:

150W of pure (thermal) glory

Fender women use argon gas shrouding their soldering target.
I was informed this approach eliminates flux necessity, cleanup free.
But this adds to operating costs.
Is this true?
In mass manufacturing, the populated pcb is "dipped" in molten solder to affix the population.
They must retain that envelope therein noble gas saturated, but this is likely "unopen" as not in fender women workbench operations (losses argon minimal "unopen" mode)

[Mick Bailey]

Argon is used in MIG welding processes. Where did you hear of it being used in electronics assembly work?

Factory workers are soldering clean, new components. No surface prep is needed. They aren't soldering used parts, or ones bought off e-bay or contaminated with polish. Also, the flux, iron temperature and solder alloy is all predetermined in a factory environment.

Some pots use tinned casings that are easy to solder. If your pot has is zinc-plated then this is more difficult and you need to use a flux that's capable of being used with zinc, or clean the component back to the base steel.

The solderability of materials varies, especially when contaminated with oils or waxes;

https://en.wikipedia.org/wiki/Solderability

[J M Fahey]

Fender women use argon gas shrouding their soldering target.
I was informed this approach eliminates flux necessity, cleanup free.
But this adds to operating costs.
Is this true?

No, it's not true.
As noted above, Argon is used in MIG soldering, an absolutely different process and unused in Electronics assembly.
Its only use lies in soldering together folded chassis ends to make stronger, there we are talking actually melting the base metal, which to boot is steel or aluminum.

Ever saw a Fender (or any other on the planet) PCB with steel or aluminum tracks, which get molten so they would solder better to parts legs?

Or a grounding wire MIG soldered to a pot case?

The "Fender women" you mention are using plain soldering irons, with standard flux filled solder wire.
There is smoke at every solder joint made, while argon or any injected gas would spread it away or make it unnecessary ... leaving aside that it would also cool the soldering tip and make it useless.

In mass manufacturing, the populated pcb is "dipped" in molten solder to affix the population.
They must retain that envelope therein noble gas saturated, but this is likely "unopen" as not in fender women workbench operations (losses argon minimal "unopen" mode)

An entirely different operation, don't understand why you even mention it here.

Yes, in such mass wave soldering, they *might* keep a controlled atmosphere ; absolutely unrelated to guitar amp pot case soldering.

[Shadrock2]

I just wanted to say that you can solder to zinc plated parts if you use a flux that contains zinc chloride. However... (pause for emphasis)... you have to be very fastidious in removing the acid flux from your work when you are done.
I use rubbing alcohol (the water in it helps dissolve the acid) and swabs. Also as was mentioned earlier, there is no substitute for a bright shiny metal surface. I like using "Scotch Brite" myself but fine sandpaper will do.

BTW Mr. Fahey I admire the effort you go to with your posts.

[hewo]

dissimilar metallurgy adjoining by soldering

No, it's not true.
As noted above, Argon is used in MIG soldering, an absolutely different process and unused in Electronics assembly.
Its only use lies in soldering together folded chassis ends to make stronger, there we are talking actually melting the base metal, which to boot is steel or aluminum.

Ever saw a Fender (or any other on the planet) PCB with steel or aluminum tracks, which get molten so they would solder better to parts legs?

Or a grounding wire MIG soldered to a pot case?

The "Fender women" you mention are using plain soldering irons, with standard flux filled solder wire.
There is smoke at every solder joint made, while argon or any injected gas would spread it away or make it unnecessary ... leaving aside that it would also cool the soldering tip and make it useless.

An entirely different operation, don't understand why you even mention it here.

Yes, in such mass wave soldering, they *might* keep a controlled atmosphere ; absolutely unrelated to guitar amp pot case soldering.

Okay, got it, dissimilar metallurgy, say tinned wire copper adjoining with say steel or plain iron, is afforded only when the solder recipe is compatible (wets both metallurgy) to both.
Otherwise bond is inappropriate, unless the solder recipe flux wastes the incompatible metallurgy 1st surface into a subsurface metallurgy that is compatible, but flux removal becomes paramount being it is corrosive.

It seems counterproductive to produce pot housing metallurgy 1st surface incompatible to standard electrical solder