Conductive fiber board, does location matter?

[Chuck H]

I wired a couple of amps with PTFE (Teflon) once. It was a dream to work with. Certainly overkill for a guitar amp, but no shrink, slim appearance and the way the stranding was tinned it was easy to form and route. I was just playing devils advocate above. I'd work with that stuff any time.

[cjenrick]

maybe soak the board in alcohol overnight, bake at 220 for 2 hours, solder components and spray with clear coat,

Fender use to dip those boards in wax to seal them against moisture, noticing silver face amps seem to lack this wax, maybe cost cutting by cbs.

don't think leakage currents on cap board will generate noise since noise will get swamped out by the caps,

[Randall]

If the board is prone to absorb moisture, it is going to absorb moisture, especially in the sub-tropic environment I live in. Nothing you can do like try to dry it out and seal it is going to change that. In fact, I would argue that sealing it potentially makes it worse, as it will trap the moisture that has somehow found it's way in there (and it will). Making it nice and dry in an oven is all well and good, but I for one am not willing to then put it on a stage at 90 degrees and 90% humidity for several hours and HOPE it doesn't flake out because that dry board wants to swell up and eff things up. Nope.

[Enzo]

On the other hand, a board that has soaked up enough to be a problem over the last 40-50 years is not likely to re-absorb that amount in the next couple of months. I'd expect another few decades before the treatment was required again.

[Zozobra]

I got 3 sheets of 365mm X 225mm x 3mm PTFE for £20 delivered from a surplus seller on ebay and I still have a fair chunk of it left. I've never had any problems staking turrets/eyelets. The only minor downside is that it is much more flexible than other board material so it will need more standoffs to support it. At the price it normally sells at I'd probably stick with G10 or phenolic.

[J M Fahey]

On the other hand, a board that has soaked up enough to be a problem over the last 40-50 years is not likely to re-absorb that amount in the next couple of months. I'd expect another few decades before the treatment was required again.

I bet an amp which was played at least weekly and probably more in Leo´s time, they were "working tools" for Pro or dedicated Amateurs, would have self dried every time it was turned on, usually for hours at a time.

Now a pawnshop find or an estate sale find or simply an amp which is owned by somebody who works at "something else" and just occassionally uses his amp, sometimes even months idle, coupled to a humid place, then he might develop dampness problems.

Not only subtropical places, any cold place but where it *snows* is showing enough ambient humidity.

[Mick Bailey]

I have experience of trying to seal conductive boards after drying them out and longer-term it traps moisture that's then more difficult to dry out. It's very difficult to get a reliable, 100% seal. It takes a lot longer for the problem to re-emerge though. At one time I thought I had a guaranteed fix with silicone oil. Then I tried silicone damp-proofing liquid in a searching carrier. This also worked superbly. The major problem with silicone is migration; it contaminates the entire amp and renders future repairs very difficult as it hinders soldering. It's now over 15 years since I first used this and none of the amps suffered any further problems with DC leakage.

I now warm the board and clean off any wax or residue, then bake the board under a heat lamp until there's no leakage, then use paraffin+beeswax shavings and re-impregnate the board using a hot air gun. This seems to hold up pretty well.

[cjenrick]

how conductive is wood? here is a Fender PR we did a few years ago, wood screws instead of turrets, clear coat,

no problems yet,

[Steve A.]

They still make fish paper and vulcanized fiberboard. Here's a link to one mfg but you can do a web search for local suppliers...

Fishpaper & Vulcanized Fibre - Schiller Park, Illinois - ESPE Manufacturing Co., Inc.

As I recall you need to order huge sheets (like 52" × 75") but perhaps one of our amp parts suppliers can be persuaded to stock it and sell smaller pieces... hint! hint!

Steve A.

[bob p]

i think they sell it at aes/ced. worth a look.

[Steve A.]

i think they sell it at aes/ced. worth a look.

Bingo!

https://www.tubesandmore.com/product...x-15-062-thick

And I was going to suggest that their alter ego (Amplified Parts) start stocking it... BTW for luthier tools AP has been a great alternative to StewMac.

Steve A.