UPDATE: DeVry 2830 projector Sound Amplifier-How to connect these very strange plugs?

[Jason Goldkamp]

UPDATE: https://imgur.com/gallery/K6oxIEd

I think people got confused thinking the speaker plug is a 110v plug. I took pics of the amp alone and then the speaker alone and color coded all plugs and jacks.

I'll go in order of appearance: The green and purple are on/come from the speaker. I'm assuming the purple circled jack is to add another speaker. I could be wrong. The green plug comes from the speaker and has ~25-50ft length cable.

The yellow, red, and blue plugs all come from the amp. The yellow is an ungrounded 110v plug. I will change that to grounded. The red and blue are unknown plugs from the amp. I plugged the amp into 100v for a short time to get the voltages from the plugs, but I waited for the tubes to warm for a minute or two. I also turned both volume knobs to max and had the tone at 50%. The red had 25v tested as VAC and the blue had ~3v tested as VAC.

My questions: Does the amp come out of the bottom portion of the case and the speaker plug is on the side of the amp? The amp and speaker component together to make a case, btw. I've tried to pull the amp out but it's firmly stuck in there. What oil should I use to loosen it if it is supposed to come out?

If it stays in the case, how the heck do you connect the speaker?

What are those things circled in white? is it a plug of some kind?

Does anyone have a schematic, manual, etc? Or any info whatsoever?

If I can't find any answers I'm gonna crack it open and see what the deal is inside, replace caps, add ground, etc and turn it into a guitar amp.

[Steve Lee]

Hi Jason,
I could be wrong but it looks like half of the kit is missing. What you have is the power supply and preamplifier, the main amplifier sits on top of this. That's why there are the indentations on top the sides of the frame. When it is all complete the parts stack up like a tower unit with the projector on top.

Photo 1 this is the speaker cable. Without the amp theres is no socket for this.

Photo 2 this is for an extension speaker.

photo 3 red circle is the power cable to the amp.
photo 3 blue circle line output from preamp to main amp.
photo 3 yellow circle mains input power lead.

photo 4 white circles these look like shielded coaxal inputs. and I think these are for the optical input from the projector.

I hope this helps.
Steve

[Steve Lee]

Hi Jason,
I have just been looking at some models of this amp and all of them are different. It could be that someone has changed the plugs on your amp for some reason. But without putting it on a test bench there is no way of knowing what is what.
Also at the time that these were being produced it was just after the war. Companies were just using what component parts they could get their hands on, to continue production by changing the circuitry.

This version of the amp has a speaker socket were on yours has the large plug attached.


I don't know if this is the missing part for your amp ? It really is impossible to say, as there is no printed details to any of this equipment from this company.




Steve.