Need help finding replacement choke for AC30cc series

[Mitch Roberts]

I just obtained a non-working AC30cc1 (for pretty cheap). I have determined that the choke has failed. What's interesting is that it failed without blowing any of the several protective fuses. I think the GZ-34 rectifier took it out, as it was clearly toast. SInce I don't know the history on it, it's possible the prior owner replaced the fuse, then gave up when it didn't work. The choke reads open on an ohm meter (I have it out of the amp). The schematic calls for 15H and it has around 340v going through it. I have searched high and low and the closest I can find is a Classictone 20H @ 100ma. It's supposedly made for an AC30. But there are several differently spec'd chokes supposedly made for an AC30, yet the circuits seem fairly similar from one tube-rectified model to the next. That is, they are all using a GZ-34 into EL-84's. I would really appreciate any thoughts from more experienced techs than me.

Thanks,

Mitch

[sluckey]

I would use this one...

https://www.tubesandmore.com/products/f ... 5-h-100-ma

[pompeiisneaks]

also I'd just check things around the power tubes, they're next in line after the choke and it could have harmed the passives around there as well as the power tubes themselves before the choke went.

Vox seems to be really good at under engineering their transformers and chokes.

~Phil

[Stevem]

It is way more likley that shorted power tubes and a higher then should have been fuse that burned up the choke!

It seems the original vintage chokes where rated at 10 to 20 h so the replacement 15h is a good compromise.

[Mitch Roberts]

Thanks everyone. I checked the fuses, and all were intact and correct. It's like the choke acted like a fuse. I have a Hammond choke that fits the specs fairly well. We shall see if that's it. BTW, the rest of the boards look unscathed, as I checked around very closely. Nothing burnt or scorched. The power tubes are an unknown quantity, maybe I should just order a new set to be safe. I have a couple of used but still good Mullard 5AR4 to use.

[Mitch Roberts]

Just for the record, the Hammond choke worked very well, the amp is up and running, and it sounds amazing. Anybody who is thinking about modding out one of these AC30cc series should not hesitate. I did the Lyle Calwdell mods and it worked out great. I am impressed with the quality of the build. Very heavy duty. And it has a gap in the slider board (attached to the chassis) that lets air convect up through the tubes and out through the vents. It stays much cooler that the mid '80s AC30 I had several years back. Highly recommended amp.

[pompeiisneaks]

That's good to hear, I had a Vox AC100CPH that I bought damaged to repair and that thing was a nightmare, absolute garbage. I'd stay away from the CPH series from that era 50/100 watters. Utter garbage.

~Phil