Method for Wax Coating a Fender Eyelet Board

[garytoosweet]

What's the best method?

I'm dealing with a very stubborn, very conductive board in a black panel Fender.

None of the usual tricks worked so I've pulled the board, am currently soaking it in Isopropyl, and then will stick it in a dehydrator.

If the labour-intensive process is succesful in removing the conductivity, I am considering adding a wax coating like in the later model Fenders.

I know pick up makers usually use small slow cookers to keep their beeswax melted. Tough to find one to fit a fender board.

I wonder if shaving the wax, covering the board with it, and then melting with a heat gun would be effective?

Has anyone done this and come up with a decent method?

[mozz]

I would have Doug Hoffman make me a eyelet board and transfer your parts to that. As to the wax melter, they are often big enough to do at least half of that board, then flip it over and do the other half.

[garytoosweet]

There are definitely many superior modern materials available.

This exercise is about preserving the original board, if at all possible.

Dipping it in two sections is an option.

My mind went towards dipping it flat. The last Silverface Fender I worked on with a waxed board had the wax formed around the components, creeping slightly up the sides of each part. Made me think it was perhaps dipped after the components had been placed on the board.

It's difficult to see in the photos, but when removing the big caps, the wax was formed up the side of the caps. You can kind of see it on the close up of the diodes.

[Helmholtz]

Point is that - from what I've read - Fender's board waxing didn't reliably work, i.e. prevent board conduction.

[garytoosweet]

Point is that - from what I've read - Fender's board waxing didn't reliably work, i.e. prevent board conduction.

Good point. Definitely not a perfect solution, but it does help the board from absorbing moisture and becoming conductive... at least somewhat.

After all wax's properties as a moisture barrier are well known.

If I'm deciding to keep the original board and not replace with G-10 or similar material, waxing seems like a good consideration to keep originality while improving reliability.

[nosaj]

i just recieved one of Hoffman's boards and I must say I will choose that route again. IT looks pretty sharp in black G10 Tubenit tweed overdrive. $36 shipped.
nosaj

[Chuck H]

If the board is conductive after cleaning and drying it out then I don't think any amount of further cleaning and wax saturation is going to help. I do think some of those old boards had anomalous amounts of carbon pigment and that high voltage and/or heat can eventually form conductive pathways regardless of moisture. Once that happens there is no saving them.

If an "original" board is a must for any reason there are people making the same crappy black paper boards for most BF models. Some of these repro boards have also been know to become conductive just like the originals.

There's really only one consideration at this point. Will this amp be used or kept as a museum piece? Sometimes you can't have your amp (cake) and play (eat) it too.

IMHO your options are to replace the board to make the amp functional, but not original. Or retain the board to keep it original, but not functional.

Good luck on this one.

[The Dude]

.......There's really only one consideration at this point. Will this amp be used or kept as a museum piece? Sometimes you can't have your amp (cake) and play (eat) it too.

IMHO your options are to replace the board to make the amp functional, but not original. Or retain the board to keep it original, but not functional.

Good luck on this one.

^^^^^^ THAT!...... EXACTLY THAT!

IMO, a decision must be made at some point. As Chuck says, you can't do both in some situations- have a museum piece and a playable/safe amp at the same time. So,

1) It's a museum piece- put it together and be done with it- working or not.
2) It's a player/amp that will be used - fix it right and make it safe.

Personally, and I know others have different opinions, I don't think there are many folks who would be concerned about an eyelet board being replaced- especially if it turns the amp from nonfunctional to functional.

[Mick Bailey]

I've oven-dried a conductive board and vacuum impregnated it with a mixture of 2 parts paraffin wax/1 part beeswax It looked really good initially but after a few months I got DC on the input sockets and leakage across the board. Nowhere near as bad as it was, but disappointing. I also tried impregnating another board with silicone oil, thinking something with a higher dielectric strength may work. I recall some success, but it was near impossible to solder afterwards and the creep from the silicone contaminated the whole chassis.

I've had brand new fibre eyelet boards that are conductive right away. The only 100% reliable fix that I've found is to replace the board with FR4 or similar. I liken the situation to buying an old car with original plug leads, plugs, tyres, belts and hoses. Nice to have as a curiosity, but not good for reliability.

[SoulFetish]

Point is that - from what I've read - Fender's board waxing didn't reliably work, i.e. prevent board conduction.

Totally agree. In fact, it appears that over time the wax itself becomes contaminated and compounds the problem. Almost all the problematic boards that come through the shop are from the era of Fender's waxed boards.

The fastest way to reliably fix these problems when they arise is to isolate the node/nodes which causing the problems and lift those from the board. I then use an insulated terminal (I have some insulated swage mount turrets which fit into the Fender eyelets) and attach the leads to the insulated terminal. The board stays original, but that's because VERY few, if any customers would want to pay the hourly labor charge to decontaminate the entire board or replace it. Only the most severe cases would warrant that.

Mick, the ability of silicone to migrate is incredible, isn't it?

[garytoosweet]

I hadn't heard of the wax itself becoming contaminated. Where I am, I see a lot of conductive fibreboards but never a conductive waxed board. Wonder if it is just luck or something to do with climate. Although I came up with a method to wax the board like Fender did, I decided it was a bad idea if the intention is to preserve originality, and with the reports of contaminated wax.

I did go ahead with attempting to revive the extremely conductive fibre board. In this case, the amp showed signs of being stored in a high moisture environment.

I first soaked in 99.9% isopropyl for about 72 hours. Before the soak I removed all visible Flux and other contaminants and scrubbed the surface with isopropyl and a toothbrush. The board looked extremely clean going in. After the soak, the isopropyl had a strong brown tint, so I was hopeful more contaminants had been leached out.

Following the isopropyl bath, I stuck the board in a dehydrator for about a week at around 150 Fahrenheit. I'm sure it didn't need that long but that was about the time before I could get back to it. A dehydrator is specifically designed to draw out moisture, and uses a fan to expel moisture from the enclosure as it is drawn out. Should work better than a bake in an oven.

I've reinstalled the board, left the chassis out in the open in my very humid shop for about a week and a half, testing periodically. All signs of conductivity are gone, the board seems to be 100% healthy.

No doubt, a G10 replacement would be much more reliable. But in this particular case, if the original Fibreboard can last another 50 years before needing this treatment, I'll be happy.

[Tom Phillips]

... soaked in 99.9% isopropyl for about 72 hours...stuck the board in a dehydrator for about a week at around 150 Fahrenheit...reinstalled the board...All signs of conductivity are gone...

Congratulations on that successful rehab. That was quite an effort that few would undertake.

[Chuck H]

Since the board is already installed I guess you're done with the project.?. Since the wax coating doesn't seem to make a difference in conductivity I think you're alright with where you've gone, BUT...

Fender did do the wax coating for a reason. Obviously they recognized that moisture absorption in the paper board was causing conductivity and the wax helped overall. Otherwise they wouldn't have continued the practice for the entire SF era. If you're in a very moist and humid area there may yet be trouble with the board since you've stripped it and dried it. IF it absorbs moisture again. Which it logically could eventually. Does wax help? Fender seemed to think so. I'm just spit balling now as my head goes over the circumstances but it's food for thought.

Fantastic effort. And if stripping the board fixed the trouble then I guess there's every possibility that the wax impregnation was contaminated (probably shallow). Kudos on the effort and congratulations on the success