A long time has passed since this thread was active, but perhaps it'll pop up on somebody's radar.
I just purchased a set of Langevin 5000 series modules: two 5116B Preamps, a 5117 Line amp Module, a 401-B Input Transformer, and the 5208 Power supply.
I've tracked down schematics for the 5116B and the 5208, which have been extremely helpful, but there are still some loose ends to get tied up before I run AC into this bad boy and try to test it out.
I'm hoping somebody out there might be able to help me out.
Below is a general picture of the unit. Notice the modules from left to right are the 5208, 5117, 5116, 401 and 5116.
Now the rear:
First off, the Input routing on this sucker is a little bit confusing. There's only one XLR input, which is wired into the first 5116 preamp. Makes sense. Then, the outputs of that preamp are fed into the 410 input transformer. Then, they continue through into the second 5116 preamp. From there, they finally exit out of the unit through the jacks on the front of the unit.
Why would it be routed this way? Why would there need to be one stage of amplification, followed by transformer, then by another stage or pre-amplification before exiting the unit? Can I simple re-route the inputs and outputs of these units to make them independent from the 401 transformer module, therefore providing two separate channels of mic preamps?
I can't find the schematics for the 401 or 6117 anywhere, so its difficult to tell whether or not certain characteristics are indeed accurate upon visual inspection (at least for me, somebody with minimal electronics experience). For instance, there's a multi-pin jack on the top of the 401; it very closely resembles a tube socket, though I'm not sure which tube accommodates it, or even if it requires one. The person I bought the unit from seemed to think that was a way of integrating it with the rest of the PA/Comm system of the Naval vessel he seemed to think this thing originated from (aka a multi-pin output).
This socket is pictured below:
There are also two sets of pins on the 5116 schematics that are labeled "HTR". I'm unaware of what this is short for, though I do know through my research that the pins labeled "MTR" on the schematic refer to the optional Meter that could have been purchased and installed with these units. These pins, labeled HTR, then route to a very peculiar looking unit, pictured below. I have no idea as to what this is doing. It does seem fairly obvious that each lead set is a send and return to this device, however.
I suppose my last question is whether or not the 5117 can be converted into a microphone preamp with little to no modifications. And, if so, could it be a dual channel preamp or is this unit designed to be a mono program amplifier?
Lastly (for now, anyway), I'm still confused as to where I should try and wire in some sort of output potentiometer, so as to regulate the level I send to the tape machine or A/D converters in the studio. Not to mention the fact I could really use some advice for where to insert the input pad, phase switch, and the phantom power supply!
Here are a few other more detailed photographs, for your reference.
Any and all help/assistance is greatly appreciated. I've already combed the internet for references and other tools, but the resources are wearing very thin at this juncture.