Thanks guys!! And sorry for the lack of updates - the last couple of weeks were extremely busy.
But today I finally made some progress.
mjrippe said:
Actually these jacks were common in telephone equipment. They used a single plug body with two prongs and a single cable, see photo below.
Thanks mjrippe - great info! Now it all makes sense ;D
Now the updates: I finally wired up the pcbs & transformers, as well as the screw-terminal & the 1/4" connectors:
As you can see on the pic, I found a piece of Bakelite from an old connector panel in my workshop, so I simply couldn't resist and added a small Bakelite panel to the front of the connector bracket as featured by the original units
I also started to tie up the wires routed along the upper edge of the pcbs as done in the 60s (it's my first attempt on this technique, so please bear with me)
Beyond that I wired up most of the front panel - except for the ratio switch and the meter. In the next pic you can also see the wires coming from the output transformer for the ratio circuit:
I'm not quite sure yet how to deal with the ratio circuit - I found very little information on that, and the only pics I found, showed different layouts. The same goes for the meter circuit. In the 175b the turret board for the meter circuit is mounted to the back of the meter switch. But in the 176 the ratio switch takes the position of the meter switch on the front panel - and thus, the ratio turret board is mounted to the back of that switch.
I found pics where the meter switch was mounted to the right vernier pot with the help of a bracket, with the meter turret board mounted to bottom of the chassis. If any of you have more info on that I'd be grateful.
If not I'll find a way to solve it
Apart from that it seems the VU meter is not illuminated ? There's no space for a lamp holder, and all pics of 175bs or 176s I found show now lamp above the meter. The only thing that could fit would be a fuse type lamp. What do you think?