1940 Lorenz Textophon wire recorder
 

Hi,

I started to restore this very nice machine. It's basically an improved Poulsen Telegraphone with tube amplifier, remote control and easily changeable wires housed into what is the oldest known precursor of the audio cassette.
It uses German Telefunken EF12 tubes and the like.
I wish not to alter its authentic aspect so I will empty the old capacitors to fit new ones inside.
Any technical information will be welcome.


Thanks,

David

Re: 1940 Lorenz Textophon wire recorder
 

Very nice, David.

I don't recall seeing any significant technical details in either Begun's book or contemporary Wireless Worlds - I'll dig through some other bibliographies for you just in case...

Barry

Re: 1940 Lorenz Textophon wire recorder
 

Really cool machine, waiting to see some more videos on youtube from you. :)
Cheers!
-Chris

Re: 1940 Lorenz Textophon wire recorder
 

Some early news...:
I replaced the two big fat 4,5µF motor caps. You would never believe it by seeing the original cans.
After a first try the machine turned on. The wire spooled nicely (and FAST!) but the fuse blew again.
I removed both power supply and amplifier chassis. I was surprised to find that the power supply was recently restored. Not much there: the mains transformer, the choke, 4 electrolytics (already replaced), one EZ12 rectifier and one selenium rectifier (most probably to power the relays). I was amazed by the size of the two 700µF/35V capacitors. They may be used along with the selenium rectifier for the relays.
However the amplifier chassis was never restored, so *maybe* it caused the fuse to blow, but this remains unsure. There are a few standalone paper capacitors in metal cans in the cabinet, which I will test once I have restored this chassis.
Enough for today. Maybe something tomorrow but we'll see... Stay tuned !

Re: 1940 Lorenz Textophon wire recorder
 

Yes, please do keep us updated. It will be interesting to follow the restoration of machine that both is of such a vintage as this one, and also historically significant.

Regarding blowing the fuse, I guess there's no loudspeaker output in machine like this, otherwise, if a paper cap at the input of the output valve starts leaking and the grid goes positive, the output valve can draw quite a bit of current, possibly blowing a fuse.

Re: 1940 Lorenz Textophon wire recorder
 

Just finished doing the amplifier chassis.
I refitted an external 4µF capacitor. This time I used three 1.5µF at 630V in parallel as I had them in stock, and the package fitted perfectly in the can.
Two EF12 tubes test 100% good, the third one tests at 1,7mA instead of 3mA. I guess it should still work.
There's a speaker output, although the volume should not be too high considering the tubes used.
All paper capacitors were changed. I was amazed to find one american capacitor and a few french ones too. Talk about finding parts during WW2...
The fuse blew most probably because of a shorted 4µF capacitor which recently poured some paraffin in the chassis.
Also, all grey resistors were out of range, at least 20% over the initial value, and sometimes over 30%.
Will put the chassis back this evening for another try.

The other question is how to repair a broken wire. The wire is too thick for a node and even if this was possible, the head pack won't allow this without damage. I can only envision soldering it back and grinding the solder until I obtain the same thickless as the wire.

Re: 1940 Lorenz Textophon wire recorder
 

Don't forget David, America didn't come into the war until late 1941 and Lorenz was owned by ITT, an international company, so neutral American components are quite likely at that time.

Barry

Re: 1940 Lorenz Textophon wire recorder
 

Ok, the news for this evening are not the best, but there's some progress.
The amplifier chassis is put back and the wire spools and rewinds.
The fuse blew again and this time I could hear a light "frost" noise. So I'm pretty sure that one of the remaining capacitors is bad.
There are three loose ones (easily "refitable"), one pack of four dual capacitor cans, and one strange board with two 2µF capacitors which happen to both have an unused end going to a small wheel on a screw. I don't know why but this really seems original, like if they were meant to connect something that is not usually necessary. A quick idea is a direct wire to wire copy but not sure at all. Or a direct access to the play/record head for an external amplifier or even radio broadcast. Anyhow...

Tomorrow I will fit all those capacitors with new ones and try again.
What puzzles me is how some paraffin could have dropped on the wires going to those dual capacitor cans. One or two obviously leaked and had paraffin coming out, but I can't imagine them "jetting" the paraffin toward the wires (about an inch away from the solders). I just hope it's not the big and heavy motor as it will be a real challenge to have it rewound... once removed... 8-o

More news tomorrow, hopefully better than today.

Re: 1940 Lorenz Textophon wire recorder
 

Latest news...

All canned and paper capacitors are now replaced. I kept the old capacitor tubes and fitte new ones inside. As they were smaller I padded with tissue and put some wood glue on the edges. Once solid, I coloured it in black so that it simulates the old tar.
Now the fuse no longer blows !
I can now engage the rewind option without trouble. The amplifier works fine.
The last trouble to fix, and of course not the easiest, is the mechanical system which engages the take-up reel clock-wise and releases it counter clock-wise in rewind mode (so that it's only maintained by light breaks).
I tried to turn the take-up reel manually and yes folks, I got some sounds !
So the machine is pretty ready now, I only have to understand how the take-up reel system works and how it can be repaired. All I can say is that it's either a quite hard task, or just something very easy. A technical documentation would greatly help but with such rare machines it's pretty impossible to find.
Last: my machine is model BW4. Seems to date circa 1942.

Re: 1940 Lorenz Textophon wire recorder
 

This will be the last news until I put a link of a good quality video. :clap:
The machine now works. The way the take-up reel engages in playback/record mode is a bit tricky, but it works even if I need to try one or two times, so I'll leave it as is.
The sound quality is not bad at all, although quite limited in frequency. I think 2KHz shoud be a maximum as it's meant for voice recording. But the low frequencies are excellent. I tried to record myself but I was too close to the microphone so the sound was totally distorded.
The remote control works as well, so I'm quite happy with this recent purchase.
Hopefully one who speaks German will tell me what the woman says on the wire when the video is ready.