Philco Predicta board lifted trace and trace corrosion.

[jass]

Hello i am new to this forum and a relatively newcomer to the hobby of tv repair so I work slowly but surely . I'm working on a Philco Continental with the 10L43a board. Removed the board from the chassis and discovered this lifted trace under the Horizontal output tube as well as the corrosion on the B+ trace line. Both the lifted trace and corroded B+ test good for continuity. I will be replacing the Horizontal tube base. Looking for advice on how to re-attach the lifted trace and and deal with the green corrosion Thank you

[Electronic M]

Trace lifting is common on these first generation PCBs as long as everything that was connected to the trace is still electrically connected (has continuity), and the foil isn't flopping against and shorting to something it shouldn't contact then everything is fine. If a section is missing just solder some wire in to bridge what's missing.

As for corrosion some boards added early conformal coating to the unsoldered traces to prevent corrosion ,some didn't, others just tinned all the trades in a solder bath. Bare copper corrodes over the years especially if stored in a humid environment. You can polish off the corrosion and flow solder over it to keep it from coming back. If it's not open and you plan to keep it in a climate controlled environment you could also choose to ignore the corrosion...If it hasn't chewed it open in 60 years it probably won't in another 60 in better storage conditions.

[Yamamaya42]

Originally Posted by Electronic M

Trace lifting is common on these first generation PCBs as long as everything that was connected to the trace is still electrically connected (has continuity), and the foil isn't flopping against and shorting to something it shouldn't contact then everything is fine. If a section is missing just solder some wire in to bridge what's missing.

As for corrosion some boards added early conformal coating to the unsoldered traces to prevent corrosion ,some didn't, others just tinned all the trades in a solder bath. Bare copper corrodes over the years especially if stored in a humid environment. You can polish off the corrosion and flow solder over it to keep it from coming back. If it's not open and you plan to keep it in a climate controlled environment you could also choose to ignore the corrosion...If it hasn't chewed it open in 60 years it probably won't in another 60 in better storage conditions.

I hate to be “nit-picky” here, but the terminology I have seen being used here is incorrect,
And as someone who has been in the major PCB manufacturing industry ever since HS, seeing this error all the time kind of gets under the skin. :O

The correct term for the protective layer on top of traces is the solder masking, and the lettering and diagrams over that, silkscreen.

Info here
https://www.ablcircuits.co.uk/pcb-layers-explained/

Conformal coating is a clear protective layer often sprayed on after the board is complete and passed all testing, it is a special polymeric film forming product that protects circuit boards, components, and other electronic devices from adverse environmental conditions. And often has a dye added so it can be seen under UV light.
Info here.
https://en.wikipedia.org/wiki/Conformal_coating

[Yamamaya42]

It should not TOO HARD to remove that small amount green area and get to clean copper.

As for the missing solder mask, if you REALLY want to go nuts! :P

https://www.amazon.com/Solder-Curing.../dp/B08V4QW7G7

we use something like this at work, and it may help hold the loose trace a bit.

[DavGoodlin]

Long ago, I worked at a place (in Texas) that would conformally coat all the circuit boards used in their navigation equipment assemblies' due to the expected service environment.

As a QA tech, 8 different boards used in that unit were tested on vacuum-contact jigs (specifying rework if needed) BEFORE they were sent to another station to be "potted" before assembly into a unit. When testing the assembled units, an occasional soldering-related repair needed done on a board, so MEK (methyl ethyl chloride) was used to dissolve that coating so repairs could be performed. Then it was patch-potted, showing an obvious repair.

I rarely see solder masking fail unless it has worn or scraped off. The picture looks as if corrosion crept in from the sides of that trace, like rust on a car, and the masking failed. RCA seemed to flow solder on all the traces, others like Philco, GE and Sylvania used something coating the entire board except where solder connections are made.

[Yamamaya42]

Originally Posted by DavGoodlin

Long ago, I worked at a place (in Texas) that would conformally coat all the circuit boards used in their navigation equipment assemblies' due to the expected service environment.

As a QA tech, 8 different boards used in that unit were tested on vacuum-contact jigs (specifying rework if needed) BEFORE they were sent to another station to be "potted" before assembly into a unit. When testing the assembled units, an occasional soldering-related repair needed done on a board, so MEK (methyl ethyl chloride) was used to dissolve that coating so repairs could be performed. Then it was patch-potted, showing an obvious repair.

I rarely see solder masking fail unless it has worn or scraped off. The picture looks as if corrosion crept in from the sides of that trace, like rust on a car, and the masking failed. RCA seemed to flow solder on all the traces, others like Philco, GE and Sylvania used something coating the entire board except where solder connections are made.

We CC many of the boards made here, it's the bane of my existence.
“But it was passing BEFORE it was put on!” :O
NOT ANY MORE!!

Then it comes to me for debug.
CC has a nasty habit pf finding poor/ cold solder joints that were just touching enough to work.

[Electronic M]

Originally Posted by Yamamaya42

I hate to be “nit-picky” here, but the terminology I have seen being used here is incorrect,
And as someone who has been in the major PCB manufacturing industry ever since HS, seeing this error all the time kind of gets under the skin. :O

The correct term for the protective layer on top of traces is the solder masking, and the lettering and diagrams over that, silkscreen.

Info here
https://www.ablcircuits.co.uk/pcb-layers-explained/

Conformal coating is a clear protective layer often sprayed on after the board is complete and passed all testing, it is a special polymeric film forming product that protects circuit boards, components, and other electronic devices from adverse environmental conditions. And often has a dye added so it can be seen under UV light.
Info here.
https://en.wikipedia.org/wiki/Conformal_coating

Solder mask! That's the term I was trying to remember....I haven't had to directly design new boards or do much NON-hobby work on any so I forgot what it was called. Conformal coating is basically the same function just extended in scope to the components.
Tomato tomato... Especially in 50s/60s era gear where lacquer or shellac was probably used for both applications.

[cj_reha]

I have found the mini engravers you can get at Harbor Freight for under 10 bucks work very well on those corroded boards. It removes the corroded copper but is gentle enough to leave the good stuff you can still solder to. I do a lot of work on more "modern" electronics like 80s/90s computers and VCRs which have a lot of electrolytic capacitor leakage problems and it has become an invaluable tool in my arsenal