Ampeg b12xt

[mikescott]

Hi, I have an old Ampeg B12XT 4X12 portaflex. I did update quite a few of the components as directed by a couple of Tube amp books I had. The amp sounds great but, the module VM1 was pretty much desintegrated when I tried to repair it. Here are some Pictures I took of the inside of the amp:

http://forum.thinkpads.com/viewtopic...=43960&start=0


I have had a hard time trying to figure out what the part was that was falling apart but I am pretty sure now it was the module VM1 as it supposedly controls the vibrato. The big problem is that right now there is no reverb either. It has mostly new tubes, except i'm using a GT solid state rectifier.
Can anyone verify for me for sure that module VM-1, and does anyone know where I can purchase one.

Thanks.

[rf7]

fliptops.net sells a replacement for the TM-1 module. Unfortunately, I could not get it to work for a 70's Ampeg Jet. I tried the Fender bug also, and that did not work either.

[mikescott]

Thanks for the tip, i just emailed them so I will see what they say about a replacement module.

[Rob Mercure]

Module VM1A consists of two light dependent resistors and a neon bulb - assuming that you have the same one used in the B-22-X. The original Ampeg number for the unit I'm describing is 64 40015. As it's essentially like a Fender unit with two photoresistors look do a Google search for crafting a homemade Fender unit (I can't remember the specific photoresistors needed). Basically a Ne-2 bulb and the two resistors inside a piece of shrink wrap tubing with the ends sealed with some black RVT - there are some folks who've subbed a LED for the Ne-2. It's been a few years since this was discussed on this forum, or Ampage, but I believe it would be fruitful to search the archives cuz I know the info was once posted here.

Hope this helps

Rob