Premier 12 help

[SolderSlinger]

I need a little help "fixing" a Premier 12. I need pictures of the main PC board assembly, both top and bottom. The amps were modified. My goal is to return the amplifiers to stock. There are missing components. I need a visual aid to determine the original component placement.

Thank you for your help in advance,

Jeff

[admin]

If you have not done so, I would pull the schematic as this will give you information about proper components and setup: https://www.conradjohnsonowners.com/viewtopic.php?t=128

Unfortunately, I don't see any good internal pictures of the Premier 12. I found a low resolution picture here: https://monoblocktube.com/conrad-johnso ... -boxes.php

Good luck and let us know how it goes.

[SolderSlinger]

Thanks, I have the schematic, just looking for a component placement visual guide. There are quite a few pictures of the bottom but I haven't found any of the top.

[admin]

When you bought the amp, did they not tell you what kind of modifications were made? Often you can tell by just looking at the components,... different manufacturer of components, solder points may look different than most, components just look newer than others.

[SolderSlinger]

Backert Lab modification. It's a fairly involved modification. Foil traces cut in multiple locations, addition of 3 small circuit boards with one board for each small signal tube socket, and many components removed from the CJ PC board. The small signal boards have up to 7 transistors, and 2 reverence voltage ICs.

[admin]

Maybe you can email them with the serial number of the unit. Maybe they can tell you exactly what was replaced/modified? Obviously, any new boards will have to go.

[SolderSlinger]

Thanks again. Because of the nature of their business, they will not provide any supporting information. I also contacted CJ, and Jeff will not provide any supporting information.

I understand and respect both Backert Lab's, and Conrad Johnson's position. They need to protect intellectual property.