green solder joints?

[carboncomp]

Seen a few builds by JMI and DAM with green solder joints (assuming this is a flux, but that's a guess) so, what is this and why? 

[Jazznoise]

Special St. Patrick's Day solder? 

[John Lyons]

^ +1  
I think it's just an abreation in the lighting.
Post a pic...

EDIT: Like this?



That is just a marker or some colored something or other to show that the joints were tampered with.
Possibly some type preservant...

[davent]

Maybe just green nail polish, comes with it's own brush (works well as a paint-on insulator).

dave

[carboncomp]

those JMI's are fugly....but also though i saw that green on some GB-83 shots on the switch, but as you say John, its probably the lighting.

[John Lyons]

Huh, I didn't notice the Greasebox switch greenies.
I think it's the same thing...not just the lighting.

[tonyharker]

Quality control to show that the joints have been checked.

[carboncomp]

Quality control to show that the joints have been checked.

Quality control but, its a JMI pedal 

[duck_arse]

back when, the audiophile types would use "a special" green felt pen to draw a special green line on the run-off part of an audio cd. this improved the sound quality. obviously.

maybe a job-lot of those special green pens, pressed into service doing audio improving on solder joints.

[J0K3RX]

Maybe it's a odd attempt at some sort of green conformal coating? Where I have worked, when we would do board/trace repair we were required to use green, blue or red overcoat pens to cover up the exposed copper and solder where the repair was done. Prevents corrosion, shorting etc.. Doesn't look like what they are using because it comes out thick and sticky... Looks like a Sharpie or some candy green clear nail polish to me... I see people use green Loctite on trim pots to keep then from creeping/moving... Seems like a novelty kinda thing, doubt they are doing UV inspection...

http://www.techspray.com/product-info.php?pId=98&cId=1

[greaser_au]

Quality control to show that the joints have been checked.

Yes!  it's an old fashioned thing, though, haven't seen it used in many years.
During factory quality control, work will be inspected to make sure it conforms to the company standard.  A component will be confirmed as correct, then the joints are checked, and indicated as passed with some ink or varnish applied. Anything that is not up to standard is usually returned to the original assembly operator for rework (so they learn from their mistakes).  At re-inspection,  the inspector only needs to check things that are not inked.   If the operator accidentally touched a joint that was previously ok, the ink/varnish disappears (burns/shrivels/whatever),  indicating inspection of that joint is required again.

Now the rabid collector uses this to see if the device has ever been tampered with or repaired.  <humour>The presence of that red zip tie probably halves the vintage value </humour>
   
david

[J0K3RX]

Like you couldn't "re-green" them...? Not a very effective way of tamper-proofing, at all! Silly waste of time and effort in my opinion and doesn't really look all that cool! And I always like to have my battery connector shorting across my circuits(good thing there is no external power on that!)... makes for trouble shooting fun for all

[greaser_au]

Like you couldn't "re-green" them...? Not a very effective way of tamper-proofing, at all! Silly waste of time and effort in my opinion and doesn't really look all that cool! And I always like to have my battery connector shorting across my circuits(good thing there is no external power on that!)... makes for trouble shooting fun for all

re-green them?  indubitably...  but even if you perfectly match the colour and then age it somehow it won't quite match the other green for another 20 years and you'd be busted as a fraud...  and that 'anorak' collector with one pristine example of every single pedal ever made in the universe - none of which has ever been sullied by the presence of a battery or a filthy, dirty little signal - in his humidity controlled big glass case will tell all his other 'anorak' mates to avoid you.      

david

EDIT: addition of further cynical and sarcastic humourous references to the typical collector stereotype!

[amptramp]

How do you probe voltages with this stuff on?  I am used to the MIL standard that requires red paint on completed solder joints so none are missed and I have seen it often.  One trick technicians used in the past was to make a probe out of a banana plug and a #28 tuberculin needle.  Great armour-piercing probe that gets through paint, insulation, wire enamel and anything else in the way of the wire.

[Thecomedian]

they should totally do like on the bottom of bonsai pots from japan or china, and have a stamp with complex characters or hieroglyphs to mark the solder joints. That'd prevent forgeries much better.

[PRR]

It's not anti-forgery, it is as David says-- to track joint-inspection at the factory.

Solder joints are THE NUMBER ONE cause of dead-at-final-test problems. Even (especially) at "no quality control" operations. It was bad enough in radio, but it was crushing in computers (100,000 joints at 99.999% perfection means the average computer does not work). Joint tracking was part of the answer. Even small assembly shops found it useful.

Anybody who thinks an unmarked joint is proof of tampering has not worked with enough (known un-tampered) boxes. Even good shops miss a solder-mark or even a whole solder-joint. Sometimes it works for 10 years before catching fire (this was a 300W amp).

If you want to defraud collectors, you wash-off the factory marks, mix-up a similar stuff, and mark it yerself.

> How do you probe voltages with this stuff on?

The non-MIL stuff is wimpy. Hardly nail-polish. More like weak shellac or even water-base. I find the lead-oxide on very old gear much more of a problem. That's why probes have points. Only rarely have I resorted to a needle or knife. And simple inspection-marks are rarely over the whole node (see John's picture: 90% of the blob is covered but entire leads are naked).

[newperson]

Plenty of these green marks in a Farfisa. 

[greaser_au]

One trick technicians used in the past was to make a probe out of a banana plug and a #28 tuberculin needle.  Great armour-piercing probe that gets through paint, insulation, wire enamel and anything else in the way of the wire.

Yes. Even THOSE are now vintage unobtanium (at least down under)...

david