63 AC30 melty PT

[gtomax]

My 63 AC30T has all original parts, transformers etc. I'm going to go in and give it a recap and noticed (also smelled) that the wax in the PT has repeatedly melted/rehardened during its life. Not unusual as I understand it but not comforting.

What is the consensus on removing it for storage/originality and replacing it for regular use with a repro PT?

I find myself using the amp less because when it warms up the smell of it slowly cooking the glue/wax makes me nervous.

[pompeiisneaks]

I'm no expert on this, so I'm going to say wait for a better confirmation.

I think when older amps warm up, the smell is often the combination of say the wax and the dust that's built up. It's likely not a problem at all.

From everything I understand they don't make transformers like they used to, so likely you'll get tonal changes if you swap out the transformer, but your call. If you're worried about potentially harming it, I'd instead make sure to give it a complete once over everywhere to ensure all components are good, or if you don't know how to do that, take it to a tech to make sure it's safe.

I just want to be sure I'm not the one responsible for you destroying your priceless amp, so don't count me 100% right on this....

~Phil

[Colossal]

Melting wax is an issue with those old AC30 PTs. As for a replacement, you could have one wound to deal with today's higher mains voltages. The early Haddon PT, for instance, had a 117VAC primary, in addition to the 220, 230, and 240V taps and 285-0-285V secondaries. Mains voltages routinely run hot now, 120-125VAC is common. So, this will cause the secondary to run quite a bit hotter than intended. If you decide on a clone replacement PT, you could use a variac however to shave off the mains voltage. Classictone and Mercury offer high quality replacements.

What year is your amp? I'd love to see photos of the PT, choke, and OT, if you are so inclined to take some and post.

[gtomax]

Thanks for the quick thoughts! I'll def take some pics and post them.

It's a late 63/early 64. Brass vents, copper panel, blues. Not top boost, treble model. I've got Albion transformers and thrilled with the tone, especially the OT. When I got it shipped over from the UK the previous owner had hooked up the speakers to the wrong impedance tap in the junction block so it was half powered and I'm amazed it didn't blow the OT. They must not have played it like that too long/loud.

I've got 118v average at my wall and i'm not worried about functionality of the circuit generally (and have enough experience building and restoring to know the warning signs) but early 60's british gear wasn't exactly 'reliable' and it might as well be candle wax gooped all over the PT at this point .

I'm not worried about tone changes from a proper spec'd replacement PT just wasn't sure if the wax "expulsion" was a concern for shorts or not. I'd rather change the PT to play it, keeping the original safe in a box, than lose the original and maybe more things inline if it gets hot and goes poof. Lack of ventilation in this chassis/box is abysmal.

[xtian]

What year is your amp?

OP said in post, 63 or 64.

Weren't these amps DESIGNED to combust, providing stage ambiance?

[Colossal]

What year is your amp?

OP said in post, 63 or 64.

I glossed right over that

Thanks for the quick thoughts! I'll def take some pics and post them.

It's a late 63/early 64. Brass vents, copper panel, blues. Not top boost, treble model. I've got Albion transformers and thrilled with the tone, especially the OT. When I got it shipped over from the UK the previous owner had hooked up the speakers to the wrong impedance tap in the junction block so it was half powered and I'm amazed it didn't blow the OT. They must not have played it like that too long/loud.

I've got 118v average at my wall and i'm not worried about functionality of the circuit generally (and have enough experience building and restoring to know the warning signs) but early 60's british gear wasn't exactly 'reliable' and it might as well be candle wax gooped all over the PT at this point .

I'm not worried about tone changes from a proper spec'd replacement PT just wasn't sure if the wax "expulsion" was a concern for shorts or not. I'd rather change the PT to play it, keeping the original safe in a box, than lose the original and maybe more things inline if it gets hot and goes poof. Lack of ventilation in this chassis/box is abysmal.

I bet that is a killer sounding amp! A wound up AC30 is a thing of beauty! That's great your wall voltage is low-ish. Mine is a toasty 124-125V.

[pdf64]

I suggest not to be concerned about the wax. If they hadn’t cheaped out, and had specc’ed them to be potted properly with resin, you would be none the wiser.
Generally, JMI iron spec seems otherwise pretty good.
If you can’t help worrying, or you just want to implement mitigation to prevent further tube failures overheating things, consider fitting a HT fuse, eg F300mA in the HT CT’s 0V return.

[gtomax]

Smart about the fuse - gonna do that! Reversible and will let me sleep at night.

The old stories about throwing one of these down a flight of stairs and then it working is dubious at best. What a sound though.

For more reasonable SPL I found one of the crazy rare "mystery amps" - essentially a 63 copper panel AC10 SRT but in a combo cab with 3 alnico 10's like a bandmaster. Had a busted internal support so I built a trapezoid head cab for it and it sits on top of the AC30. Plugged into the AC30 blues like an extension cab it's a glorious thing as long as you don't turn up the "reverb" past just on

[gtomax]

I suggest not to be concerned about the wax. If they hadn’t cheaped out, and had specc’ed them to be potted properly with resin, you would be none the wiser.

Hypothetically if all the excess wax melts out and disappears it should have enough to keep the windings isolated? Or when I start to notice globs falling off I should think about replacing it for safe keeping?

[xtian]

The wax or resin used to pot a transformer is not meant as an insulator. The wires are already insulated with a coat of enamel, same as guitar pickups and speaker voice coils.

[pompeiisneaks]

I think you could maybe fill the transformer with a better material, some form of resin, can't remember what it is, if you really wanted to, but would require pulling that one out, heating it up enough in an oven to melt out the was but not harm the actual transformer.. then refill/repot it with something better? Seems like a lot of work though

~Phil

[sluckey]

I don't think the problem is with the PT, but rather the layout and cabinet design. The cab retains too much heat. I'd look toward adding a fan for ventilation, or even using an external fan to move that hot air.

[10thTx]

I don't think the problem is with the PT, but rather the layout and cabinet design. The cab retains too much heat. I'd look toward adding a fan for ventilation, or even using an external fan to move that hot air.

Good idea!

[Roe]

one of my PTs smell soap when it gets warm - what could that indicate?

[Colossal]

one of my PTs smell soap when it gets warm - what could that indicate?

Good clean tone!