RCA BC3B Consolette

So I am starting a complete restoration of my RCA BC3B consolette, but I'm not sure where to start. I am ordering caps for the pre amps b/c they'll surely need replacing, the 6 large 40/40/40uf caps in the power supply might need replacing too but they're very expensive so I want to try to avoid replacing those.

There are 5 pre amps with utc input transformers, and 2 booster channels that could easily be turned into pre amps. Apparently the pre's have about 46dB of gain.

There is one large output transformer, plus a mono power amplifier as well.

I'm not sure what I should do with this cool piece of equipment. I'd like to add direct outs to the 5 pre amp channels, and somehow wire the switches on the front to take the channels in and out of the mono mix buss, so I can use it as pre's or as a mono summing amp.

I still haven't even powered it up because I'm afraid to blow any old caps. I need to buy a variac.

Does anyone on this board have any experience with these pre amps or consoles? potentially a manual or schematic you're willing to share? (I found the manual for the BC3C which looks very similar). http://binauralaboratories.net/lab/consolette/mainrca.htm

Thanks

I think you are right to start with re-capping it. Start with the power supply. Get that working and you can use it to test the rest of it as restoration proceeds. Regarding the expensive caps, some people remove the insides of the cans and put modern caps inside. That way it looks original but has modern parts inside.

Cheers

Ian

+1 on recapping the supply. Just restuff those old cap cans with something decent.

the 6 large 40/40/40uf caps in the power supply might need replacing too but they're very expensive so I want to try to avoid replacing those.

Click to expand...

EC5050-500 can get you part of the way there and the price is nice.

http://taweber.powweb.com/store/capord.htm

If you can find a difference between the BC3B and the BC3C, I'd like to know it.  My bet says a mechanical part change that you'd never see unless you owned both. 

The PSU caps the the absolute first thing you want to replace. 

The monitor amp needs to be either:
1) run, and loaded resistively if not used, or
2) PSU needs to be recalculated for lack of monitor amp current draw, otherwise you over-voltage everything else in the console.  Also, lack of monitor amp tubes may give higher than desired filament voltage, check it and consider changing PT pri taps to adjust. 

Direct out wiring will be dependent on whether you ever want live mic mixing, as originally envisioned.  If you do, that will limit your choices.    If the piece is clean overall, especially with no additional holes drilled in the panel, I'd refrain from modding it as you'll kill street value. In that case, maybe better to unload it and use the funds to build what you want.  It's certainly not a practical 5-7 channel device, and there are still plenty of retired radio people who want one in their ham shack. 

Alright, recapping the power supply is first. I am planning on keeping this thing, but not modifying the chasis or anything. My goal is to modify the electronics slightly so that it can be used as a functional 5 channel pre amp while still keeping its original functionality if at ALL possible. It might not be possible, I'm definitely not drilling into this thing or taking any of the original parts out.

I think the BC3C and BC3B are slightly different. The BC3C schematics have slightly different capacitor values in the pre amp channels than what's on my BC3B.

Has anybody used these pre amps btw?? how do they sound???

Also, would it make sense to install some kind of fuse in the power supply section, and potentially replace that old selenium rectifier?

You may be looking at replaced caps in your console, differing from stock.  Even if not, you can take either version as gospel and have a functioning console. 

I've heard good reports about these preamps, but never fired one up when I had one in my posession.  The new Slate Digital tube console is an emulation of this RCA, modeled on tests from 3 different units. 

Selenium rectifier is in control of the relay section; if you aren't using that (prob not) then disconnect it's AC input. 

The block diagram shows a fuse, I don't remember where it lives. 

Ian said:

I still haven't even powered it up because I'm afraid to blow any old caps. I need to buy a variac.

Click to expand...

You don't necessarily need to use a Variac. Use a light bulb in series.

Thanks guys, this is all really helpful.

http://www.groupdiy.com/index.php?topic=25576.0