Old brittle insulation on circuitry is vibrating/buzzing. Easy solutions?

[Triocd]

I have a 1961 Gibson ga5 that has some buzzes at certain frequencies. I pulled the chassis halfway out today while playing and I found that a lot of the insulation over the capacitor and resistor leads is not tight to the leads and is able to rattle/vibrate. Believe it or not the vibration is really loud. I’m sure the insulation was flexible at some point but after all these years it’s hard.

Is there any way to lock the insulation down? Can I put some silicon (or something else) on the leads and “glue” the insulation in place?

Is the insulation definitely needed? I was thinking I could carefully cut the loose ones off with a razor if they aren’t needed.

I’m hoping for something quicker than unsolder, add new shrink tubing, and resolder since there are several that buzz all at different frequencies.

Any ideas? Thanks

[pdf64]

Don’t use silicone as it’s fume will corrode metal.
Would a small dab of clear, ‘rubber solution’ type glue into either end of the offending insulation be feasible?

[Chuck H]

Have you confirmed that the loose insulation is actually what you are hearing? Like temporarily securing it with tape, etc.? If yes, then I don't know if applying an exterior product can help because it probably won't penetrate and re secure the insulation but just act as a coating on the still vibrating insulation. As a house painter I can tell you that you have to remove any loose paint before painting or it will just take your new paint with it when it fails. In other words If the insulation isn't adhered to the wire now then the insulation and whatever you coat it with won't be. Obviously if it's all cracked and decomposing you should replace the lead wire entirely.

[Jazz P Bass]

Rather than making a mess of things, why not simply replace the brittle insulators?

[Chuck H]

Rather than making a mess of things, why not simply replace the brittle insulators?

Right?!? How much wire can there be in a GA5? Even with some snarky connections and shrink tube you could probably rewire the whole thing in a couple of hours.

[Triocd]

Have you confirmed that the loose insulation is actually what you are hearing? Like temporarily securing it with tape, etc.? If yes, then I don't know if applying an exterior product can help because it probably won't penetrate and re secure the insulation but just act as a coating on the still vibrating insulation. As a house painter I can tell you that you have to remove any loose paint before painting or it will just take your new paint with it when it fails. In other words If the insulation isn't adhered to the wire now then the insulation and whatever you coat it with won't be. Obviously if it's all cracked and decomposing you should replace the lead wire entirely.

Definitely confirmed it’s loose insulation. I had a looper pedal playing certain notes yesterday while I poked around with a chopstick. On certain notes you can visually see different pieces vibrating. When I gently put a chopstick on each piece of insulation the buzzing stops.

[Triocd]

Right?!? How much wire can there be in a GA5? Even with some snarky connections and shrink tube you could probably rewire the whole thing in a couple of hours.

Yea, I would love a couple free hours to set aside and rewire my amp, but I have a 6 month old and a 3 year old while playing in a band, so the few moments I get for music time are few and far between.

[Tom Phillips]

The insulation you are referring to is know as "Spaghetti insulation." As you stated it was added to the solid lead wire of capacitors and resistors and it always was loose on the solid wire lead although it may have been softer / more flexible when it was new. I's fairly certain we are not hookup wire insulation that has become loose over the life of the amp.

The insulation tubes were used to prevent the bare component lead from making electrical contact with an adjacent lead / chassis etc. However, the tubing was often placed on many components that didn't really need it. This is because it was cheap and easy to install when the amp was being constructed and it was more practical to just tell the assembler to use it everywhere than to define specific component leads that needed it. In addition the "everywhere" approach addressed the issue of variability in the placement of the components within a hand built product.

As to a fix for your situation since you told us that you verified that the insulating tubing IS making the noise you hear, your suggestion to simply remove the spaghetti insulation is viable. However, we need to determine which particular pieces may be safe to remove. Can you post photos of your specific amp guts?

[Chuck H]

Well, that was just an extreme scenario. It doesn't sound like you'll need to rewire the whole amp. You might well spend as much time experimenting with goo as you might just doing repairs. And whose got time for amplifier problems? Certainly not you. So do like Jazz said and just repair the failing leads. Even as a novice I noticed that if you lay out the parts you'll need it goes pretty well once the iron is hot and you're in there. Good luck either way.

[Chuck H]

The insulation you are referring to is know as "Spaghetti insulation." As you stated it was added to the solid lead wire of capacitors and resistors and it always was loose on the solid wire lead although it may have been softer / more flexible when it was new. I's fairly certain we are not hookup wire insulation that has become loose over the life of the amp.

The insulation tubes were used to prevent the bare component lead from making electrical contact with an adjacent lead / chassis etc. However, the tubing was often placed on many components that didn't really need it. This is because it was cheap and easy to install when the amp was being constructed and it was more practical to just tell the assembler to use it everywhere than to define specific component leads that needed it. In addition the "everywhere" approach addressed the issue of variability in the placement of the components within a hand built product.

As to a fix for your situation since you told us that you verified that the insulating tubing IS making the noise you hear, your suggestion to simply remove the spaghetti insulation is viable. However, we need to determine which particular pieces may be safe to remove. Can you post photos of your specific amp guts?

Right. Perfectly safe to remove it from signal leads. Not a good idea to have any long, bare HV leads though. Still... Is it really faster to cut that stuff off carefully enough to avoid damage than it would be to just snip it, slip off the "spaghetti", remove the clipped wire and roll the other end near the component with needle pliers and solder in some lead?

Snip, slip off spaghetti, solder/remove bare lead, roll component end, solder in lead wire.

The only easier solution I can imagine is if there is enough room between the spaghetti and the leads to syringe in some goop. Though I'm not sure what. Whatever might get used, make sure it's not black. Most black pigment is carbon and can form into resistive paths when mixed with some adhesives and subjected to HV and heat. I have personal experience with this.

[Tom Phillips]

The attached photo shows an example of 1953 Gibson amp wiring. The wiring is such that I think the insulating tubing on the components leads is needed. I like Chuck's suggestion of injecting some goo in the tubing. It might be sufficient to add a drop of superglue to the end of each vibrating tube with the chassis positioned to let the superglue drop run down inside the tube.

It would be best to see photos of your 1961 GA-5 before we say more. This is a strange problem and maybe your build is not factory original.

[Triocd]

[Enzo]

Nice straight wire through a nice straight piece of spaghetti, and it rattles? Room inside the tubing for space all around the wire.

Try this, get out your needle nose pliers, and on the offending pieces of wire/insulation, grasp in the middle and give it a little crimp/bend. Something to wedge the wire in place so it won;t rattle. I bet a tiny S bend in the center of each sensitive wire will silence most of them, and no rewiring needed. At least not in those spots.

Note in Tom's photos, some spaghetti wires are straight, and some bent in a curve. DO the curved ones rattle, or just the straight ones?

[Triocd]

Above I showed a couple pictures of the guts and pointed to the offending buzzing spaghetti pieces. The only one that I can’t visually see rattling is the 4th picture. I can’t confidently say that the spaghetti in the 4th picture is buzzing but when I put the slightest bit of pressure on the spaghetti in that photo the buzz stops. It could be the tube socket in this case, but I can’t be sure.

The other photos are 100% loose spaghetti. Based on the photos can I remove the offending spaghetti pieces without some negative side effect? Thanks!

[Tom Phillips]

...Based on the photos can I remove the offending spaghetti pieces without some negative side effect? Thanks!

I would not remove any of the insulating tubing. There is a chance that the resulting long bare lead could touch another conductive surface later in the amp's life. The problem leads are the straight pieces as Enzo pointed out. I suggest you start by forming those leads into a gentle "S" bend. It doesn't need to be much of a bend and you could even do it with finger pressure after you make sure the amp is unplugged and all the capacitors have drained. The result will look nice and should solve the buzzing problem. I have re-used the old spaghetti insulation when doing restoration on Gibson amps alder than yours and I have never had a problem with buzzing noise caused by the spaghetti but there are always exceptions.