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Old 29th Sep 2011, 2:07 pm   #6
david winter
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Join Date: May 2008
Location: Paris, France
Posts: 336
Default 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.
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