How to wire a 2 core plug for '60s Revox Tape Machine? Help!

[ban-all-sheds]

In most of the target markets for this recorder, there would not have been any way to guarantee which way round to connect the mains conductors.

That, of course, is quite true - hadn't thought of that.

When did they stop connecting one of the supply conductors to the chassis? Or was that only done on AC/DC sets?

However....

The only time this becomes less safe is if the internal fuse blows, and you then decide to open up and work on the equipment without unplugging it.

Given that it is utterly unrealistic to buy a 40+ year-old valve tape recorder which is of sufficient sophistication/complexity as to have made it cost, when new, the equivalent of over £2,000 and to expect to never need to open it up, why not open it up now and connect line to the terminal with the fuse?

 

[Paul_C]

When did they stop connecting one of the supply conductors to the chassis? Or was that only done on AC/DC sets?

It was generally just AC/DC sets, although of course in such sets the chassis was entirely contained within the insulating casing, knobs had to provide insulation from potentially live control shafts, etc.

Even with polarized plugs (e.g. 3-pin BS546/BS1363), when used in a house which was fed from the negative side of a 3-wire DC supply system the chassis had to be live, otherwise the polarity would be incorrect for the rectifier.

Although AC-only sets generally had no direct chassis connection, they still often had filter capacitors connected between one or both sides of the incoming supply and the chassis.

 

[danechip]

Christmas tree light's, green wires with silver inner strands, connected either way round in a plug and 3 amp fuse not even 20 years ago. They may have had a fuse bulb in series, but still live up until the blown bulb. MI's would always recommend you remove from the supply before changing bulbs or inspection. Ya know, screw in type you could physically touch the side of the bulb (I did aged 7) !!

 

[joinerjohn]

The Revox G36 (736 in the UK) was a serious bit of kit, not just for home recording , but also found it's way into some studios (high speed version)
Quite a few groups would have been recorded on Revox tape decks in the mid to late 60's. As others have said, best to open it up (unplugged) and bell out the 3 amp fuse to find which wire goes to it.
Best of luck finding valves for it though.

 

[Farringdon]

Thanks everyone. I looked into opening the G36 but it's in its original flghtcase so quickly gave up the idea.

So I guess I'm just going to wire it randomly and assume it's going to be okay.

 

[bernardgreen]

I assume the fuse is accessible without taking the case apart.

The live should go direct to one end of the fuse. Take the fuse out and measure resistance from each end of it's holder to each of the two wires. ( 4 readings ) the wire with the lowest resistance very close to zero ohms wil be the Live wire.

The other end of the fuse will connect to the transformer primary coil. the other end of this coil is connected to neutral so that end of the fuse will also give a low resistance reading to the neutral wire but not as low as the live end of the fuse does to the live wire.

EDIT , measure from the fuse holder clips and not the removed fuse itself.

 

[aptsys]

^^ Good call.

 

[ban-all-sheds]

I looked into opening the G36 but it's in its original flghtcase so quickly gave up the idea.

What do you plan to do when (not "if", when) it goes wrong?

Do you even know that it works now?

 

[thatbloke]

This is a good place to find out info on older kit.

http://www.vintage-radio.net/forum/index.php?s=f6a18003d3a3f56595de29f632a31762

 

[danechip]

BAS, of course it will go wrong, it's mechanical. Doe's not mean it will die imminently.

Fella, I love your comments, I was your greatest fan !!, But i can see why now how you pish so many off.

You commented last night to my post after you poked me for an answer "that won't work".

Would love your expertise as to "why"?

Dan.

 

[Sureitsoff?]

Thanks everyone. I looked into opening the G36 but it's in its original flghtcase so quickly gave up the idea.

So I guess I'm just going to wire it randomly and assume it's going to be okay.

I have a G36 and if it wasnt buried in the spare room I would gladly have a look for you. I took mine out of the flightcase and put it in a homebuilt sloping case and as I recall it is not difficult to get out. After removing the head cover, the two chrome posts are removed as they hold the grey plastic deck on, I cant remember if the control knobs just pull off but if you are logical it is not difficult to get it apart, nothing will require great effort to seperate. The machine is held in to the flightcase with machine screws down each edge.

Hope this helps

 

[ban-all-sheds]

BAS, of course it will go wrong, it's mechanical. Doe's not mean it will die imminently.

Indeed - which makes me wonder why someone who can't even work out how to get the case open would risk buying one...

You commented last night to my post after you poked me for an answer "that won't work".

Would love your expertise as to "why"?

I didn't say it wouldn't work, only that I didn't think L&N should go either way around (given the fuse).

But that was before I'd been reminded about the non-polarised plug legacy....

 

[Farringdon]

I got a response from the guy who sold me the tape machine and he said it shouldn't matter which way round it's wired and I should not bother opening it up.

Looking at the cable I found a "dumber" way of solving the issue. I think I can just about tell which side of the cable was "squashed" by the plastic casing and thus tell the way it was wired originally. The cable has been squashed the same way for decades so you can how it was placed before from the dent. Of course the dent is only on one side. Plugged it in and the tape machine seemed to turn on fine. Only had it on for a few minutes though, will do further testing with tape later.

Thanks everyone for your advice.

ps: As to why we would buy a tape machine without much technical knowhow of such things, well how are we supposed to learn if we never try or buy? I bought it to mixdown recordings for my band, and we don't know anyone our age who has a clue about old tape machines. Everyone uses computers but we've come to realise that it doesn't have the magic of tape. None of the classic records we like were recorded on computers.

To Sureitsoff? - Is it worth always adjusting the bias and sticking to the same tape before recording on the G36? Any recommendations on tape for this particular machine? I have the normal 7.5ips version , not the high speed one unfortunately.

 

[danechip]

Looking at the cable I found a "dumber" way of solving the issue. I think I can just about tell which side of the cable was "squashed" by the plastic casing and thus tell the way it was wired originally..

Sorry, but that sounds really dumb to me....

 

[Sureitsoff?]

To Sureitsoff? - Is it worth always adjusting the bias and sticking to the same tape before recording on the G36? Any recommendations on tape for this particular machine? I have the normal 7.5ips version , not the high speed one unfortunately.

I wouldnt adjust bias etc unless you are aufait with machine line up and have the appropiate reference tapes. Sorry I cant recommend a brand of tape as I always got mine from work