A Once in a Lifetime Dream Project - Videokarma.org TV - Video

yagosaga · #1 03-17-2009, 04:56 PM

Hi,

some weeks ago, I got a surprising telephone call. I was asked to restore a German Telefunken mirror-lid prewar tv set from 1937, and to bring it into working condition. I was unsure whether I have the skills to do such a thing. I was afraid about the handling of the prewar picture tube. But nevertheless, I said yes. Two weeks ago, I got the set, and is in good condition. Unfortunately, the E.H.T. connector at the picture tube is broken (see photo). The picture tube itself is still under vacuum and has still silver getters. The filaments are also OK.

The set was upgraded to 625 lines in the 1950s. I have rebuild it back to 441 lines television standard.

The original line output tube, an AL5 special, is missing and hard to find. It was replaced by a 6DQ5. I hope that I can get an original AL5 special tube with the plate cap.

With the help of Darryl's World Converter, I could operate the set. Here are some pictures and a video:

http://fernsehmuseum.net/telefunken/img/FEVI_1_01.jpg
http://fernsehmuseum.net/telefunken/img/FEVI_1_03.jpg
http://fernsehmuseum.net/telefunken/...I_chassis1.jpg
http://fernsehmuseum.net/telefunken/...I_chassis2.jpg
http://fernsehmuseum.net/telefunken/..._1_Ablenk1.jpg
http://fernsehmuseum.net/telefunken/img/FEVI_1_CRT1.jpg
http://fernsehmuseum.net/telefunken/...nodenkappe.jpg
http://fernsehmuseum.net/telefunken/...emodulator.jpg
http://fernsehmuseum.net/telefunken/...VI_1_Spule.jpg
http://fernsehmuseum.net/telefunken/..._1_Screen7.jpg

Video:

http://www.youtube.com/watch?v=3kL5xE4aWko

Kind regards,
Eckhard

Sandy G · #2 03-17-2009, 05:17 PM

Wow...Just wow.

jhalphen · #3 03-17-2009, 06:17 PM

Hello Eckhard,

An amazing set and an amazing job you did on it, Wow!
And Thanks! for some great, high-res photos.

Are you going to post a restoration journal on your site?

Is the TV still operating on its original AC derived EHT transformer, i have heard from other pre-war set restorers that 95% of them need to be rewound.

And on the same topic, not too scared working near this high power "Neon sign" transformer? filter capacitor discharging before working on the circuitry must be quite spectacular...

Any ion burns on the CRT?

Best Regards

jhalphen
Paris/France

Dave A · #4 03-17-2009, 06:55 PM

Is the mask more square than the usual 4x3 rectangle? If so, is it a function of the timing of 441 lines?

Dave A

*zenithfan1* · #5 03-17-2009, 06:59 PM

That is amazing! Great job, very neat work!! There are more parts in that set than in half of my sets put together.

zenith2134 · #6 03-17-2009, 07:30 PM

Very impressive set. A true collector's piece.

damen · #7 03-17-2009, 07:38 PM

Wow...Good Work

ohohyodafarted · #8 03-17-2009, 08:19 PM

That is absolutely incredible. To think that this actually survived the raveges of WWII. I would love to hear the history and background of this set. Where was it used originally? How did it survive the war and where was it discovered? It seems to be in remarkably fine original condition.

Was it restored previously by another collector? Must be worth an absolute fortune.

wa2ise · #9 03-17-2009, 08:47 PM

Quote:

Originally Posted by yagosaga

Hi,
Unfortunately, the E.H.T. connector at the picture tube is broken (see photo). The picture tube itself is still under vacuum and has still silver getters.

Some conductive paint or epoxy carefully dabbed at the spot the broken off metal pin is, connecting to some high voltage wire, may be sufficient to pass the several microamps of high voltage current.

Steve K · #10 03-17-2009, 08:52 PM

Eckhard:

Deine Arbeit ist ausgezeichnet!

MfG,
Steve

klama2006 · #11 03-17-2009, 08:56 PM

Cool, is that last pick Jamie from Myth Busters?

old_tv_nut · #12 03-17-2009, 09:33 PM

Jumpin' geewhillikers, isn't that something!

How does the EHT supply work? That looks like a high-frequency coil in
http://fernsehmuseum.net/telefunken/...VI_1_Spule.jpg

bgadow · #13 03-17-2009, 09:51 PM

You make it look so easy! Incredible set...a million thanks for sharing with us!

jeyurkon · #14 03-17-2009, 10:05 PM

That's absolutely gorgeous!

Having to work on the broken EHT connection would have made me a nervous wreck.

Congratulations on your accomplishment!

John

yagosaga · #15 03-18-2009, 03:41 AM

Hello all together,

thank you for all your comments! There are a lot of questions, I try to reply to each other without mentioning the writers:

Quote:

Are you going to post a restoration journal on your site?

Yes.

Quote:

Is the TV still operating on its original AC derived EHT transformer, i have heard from other pre-war set restorers that 95% of them need to be rewound.

The set still operates with the original AC derived E.H.T. transformer and with the original E.H.T. capacitors. Both are positioned in a closed can with transformer oil.

Quote:

And on the same topic, not too scared working near this high power "Neon sign" transformer? filter capacitor discharging before working on the circuitry must be quite spectacular...

There is a blocking resistor of 10 MegOhms, which discharges the E.H.T. rapidly after switching off. In the beginning, when I worked on the broken CRT E.H.T. connection, there was a connection of the E.H.T. with the black coal outer coating of the CRT. It is isolated from the chassis, so it has full E.H.T., and when I adjusted the picture centering, I touched it with my hands. ... You can imagine how I felt in this moment...

Quote:

Any ion burns on the CRT?

No. Only a nearly unvisible small spot in the middle of the screen. The CRT is working with 8 KV E.H.T., and it has electrostatic focussing and magnetic deflection. Additional, this set has already a damper (CY1 spez) in the line output unit.

Quote:

Is the mask more square than the usual 4x3 rectangle? If so, is it a function of the timing of 441 lines?

Yes, it is. The mask is for the German 6:5 aspect ration format.

Quote:

To think that this actually survived the raveges of WWII. I would love to hear the history and background of this set. Where was it used originally? How did it survive the war and where was it discovered? It seems to be in remarkably fine original condition.

I don't know the history. Most of these sets were used in "Fernsehstuben" (public viewing rooms) in Berlin before the war, and with WW2, in hospitals for wounded soldiers. Some few sets were private. This set here was "upgraded" in the 1950s for the postwar 625 line television standard.

Most of the few German prewar tv sets were destroyed, or carried of to Eastern Europe. In the last two years, I got reports about three newly discovered German prewar sets, and I think that there are still some undiscovered in Poland or Russia, or even in Germany.

Quote:

Was it restored previously by another collector?

Yes. It was fitted with a transistor video amplifier for composite input twenty years ago.

Quote:

Cool, is that last pick Jamie from Myth Busters?

No, it was taken from the actual aired German television program.

Quote:

Having to work on the broken EHT connection would have made me a nervous wreck.

Yes. But much more nervous was the handling of the CRT. You can lot lie this set on a side without removing the picture tube. The high weight of the deflection yokes would break the neck. So, you have to remove the picture tube. I have loaned a helmet with a visor from our electrician, and weared a winter coat and leather glows when doing it.

Kind regards,
Eckhard