It is quite possible, if you have been fooling with early Gibson or Epiphone amps, that you have run into the Sprague 102C84 network. When I did, I found precious little on the internet.
My inaugural post on this blog is dedicated to the memory of this damn thing.
What is it? It is a network of resistors and capacitors in one funky square package. It has three leads coming out the bottom and was apparently made specifically for Gibson amps. This image is from the Gibson Master Service Manual (Hawk, pg. 318) and while hard to read, it’s also hard to mistake.
The circuit inside is just below it and shows values of 500 pF , 220k (for both resistors) and 0.0047 μF (5%). I have also seen this network drawn on a 50′s GA-5T schematic but I can’t find the schematic again. The pre-crestline 5T is pretty rare apparently. You can tell it’s the 50′s version because it has four tubes, not the 5 tube Crestline.
The 5 tube GA-5T Crestline is how I got into this mess, but that is another story.
Answering my own questions here, but right after posting, I found the GA-5T Pre-Crestline schematica at : http://tdsl.duncanamps.com/link.php?target=01256DC3&mode=schematic
Thanks a BUNCH!!!! I haven’t been able to find anything else on the 102c84 anywhere, and it was kickin’ my butt. Rebuilding this rusty old GA-19rvt has definetely been an experience.
My pleasure.. I had been doing that dance for a while when I started this blog, so it was a no brainer to write this as my first entry.
It was also nice to be on top of the google search results for a while :-)