I want an old plug.

October 15, 2020 5:23 AM

Please help me identify a jack/connector on my old stereo.

I have a vintage ('78-'81) Rotel RV-555 stereo receiver recently rescued from a junk box. On the back there's jack/connector labeled "DC-DC converter", four pins in a Y configuration providing +12V, +24V and -24V. I have no idea what its original intended purpose was, but because this unit doesn't have a switched 120v receptacle I'd like to use this one to power a bluetooth adapter. The obstacle to doing this neatly is that I haven't been able to identify the socket type so that I can find the correct plug to use. It looks a lot like an apparently obscure 4-pin socket used for some CB radio microphones, but that seems an odd choice for a DC jack, and they're expensive enough that I wouldn't be eager to buy one experimentally. I was hoping to keep this cheap. Can anyone identify this thing confidently? OD is ~5/8".

posted by jon1270 to Technology (8 answers total)

That is for connecting the Rotel RV-C1 external DC/DC converter in order to power the receiver with a 12 volt DC battery rather than an AC outlet. It’s power in, so unlikely to be useful in powering your Bluetooth device.
posted by slkinsey at 5:48 AM on October 15, 2020 [5 favorites]

The company I work for makes products for healthcare TVs, and that looks like the 6 pin connector that's used on Zenith healthcare TVs. Zenth no longer exists (LG bought them), but you can still buy that plug and cable. I'm sure it has a specific name, but if you just google "zenith 6 pin TV cable", it'll come up.
posted by jonathanhughes at 6:06 AM on October 15, 2020 [1 favorite]

Response by poster: It’s power in, so unlikely to be useful in powering your Bluetooth device.

Ok, that makes sense except that the marked voltages (fairly approximately) are there at the socket when the stereo is plugged into AC and powered on.
posted by jon1270 at 6:29 AM on October 15, 2020

Response by poster: ...I mean, I guess that still makes sense in that if the socket is intended for an external converter for input power, it would be connected to the output side of the receiver's internal AC-driven power supply. So maybe it's not intended to be power out, but I don't see why it couldn't be used that way.
posted by jon1270 at 6:48 AM on October 15, 2020

I had a quick look at the wiring diagram, and it does appear that the center and 12V pins at least are connected directly to the filter capacitors, so it seems like this would work for power flow in either direction.
posted by FishBike at 6:52 AM on October 15, 2020

If you google for "Rotel RV-555 manual" it's not hard to find a schematic that shows how everything is connected up inside.
posted by slkinsey at 6:53 AM on October 15, 2020

It looks somewhat like a socket for a 6-pin DIN 240° plug, except that it has some pins missing, their spacing is a bit off and there's no cutout for the notch that DIN plug barrels have. But those plugs are cheap, and you can try if one would fit without the barrel in place and the offending pins amputated for about US$2.
posted by Stoneshop at 11:14 AM on October 15, 2020

Response by poster: The Zenith 6-pin, with 2 pins removed, looks like the best match suggested here. I found likely-looking 4-pin connectors used for the microphones or to supply power to vintage police scanners, but they're uncommon and even taking the chance on one would cost close to $20. Before I go that way, I think I'll open the receiver and see if there's a good place to mount the bluetooth unit inside it, along with a little buck converter, so I can just hardwire everything and keep it externally clean. Thanks for the thoughts, everyone.
posted by jon1270 at 8:38 AM on October 16, 2020