How to record on a Grundig reel-reel?? - diyAudio
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Old 9th May 2003, 11:34 PM   #1
Duo is offline Duo  Canada
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Default How to record on a Grundig reel-reel??

Hi everyone.

I recently obtained a very nice Grundig reel to reel tube tape recorder. It plays okay but I really want to use it for recording.
There are a number of buttons on the front. I know how to set it between mono and stereo, and pick the track sets for mono. Also, I know then when I press a little knob labeled R/S a little indicator tube shows the signal input from my source which is variable via the volume knob on the faceplate.

There are three buttons on the bottom right hand side of the unit. One is labeled like a backwards 'Q', the other a microphone, and the other similar to an omega symbol. It seems that the microphone and omega buttons select different recording inputs but I don't know what the backwards Q one is.

The R/S button also turns clockwise and goes down. If I turn it clockwise with an input, a signal shows on the tube display but with different characteristics.

If I hold the R/S button down and then press play, the unit seems to lock into some sort of record mode, but I get nothing on the tape when I play back.

This problem has really got me stumped. I tested all the tubes and made sure that the power supply and wiring are functional.

The unit looks very similar to the TK line of Grundig players but it came out of a console somwhere in the fiftes or slightly earlier.

Please help me, I can't seem to figure this darn machine out!

I really want to record!!

-- Duo
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Old 10th May 2003, 06:26 AM   #2
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Default To the best of my memory..

Duo,

The backward "Q" was a normally used to describe a pick-up or phono source.
The Omega is the microphone input.

If I think of more, I'll post it.

E&OE

Cheers,
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Old 10th May 2003, 06:59 AM   #3
dhaen is offline dhaen  Europe
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Default Oh, I just remembered...

The Grundigs of this era used some Wima caps that looked like big Orange Drops (but not orange) which became hydroscopic.
If you disconnect each and measure, you may find they have resistance of a few meg ohms.

Some tape machines had the ability to superimpose onto an existing recording. This was done by switching off the erase head, reducing the bias and signal to the record head.
I wonder if the S/R is superimpose/record - just a guess.

Does the machine play back existing recordings?
Can it erase an existing recording?

Cheers,
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Old 10th May 2003, 07:27 AM   #4
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is the omega symbol not for a headphone>???...I`m guessing
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Old 10th May 2003, 07:56 AM   #5
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Default A rethink...

The omega is definately mic.
The reversed Q is line-in.
A third symbol (which is like Q rotated 90 deg CCW) is phono pickup.
This input was for a crystal or ceramic cartridge. These cartridges were high output, sometimes line level, and if loaded by 1 meg, would need no EQ.

More useless information where that came from...

Cheers
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Old 10th May 2003, 02:21 PM   #6
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Hmmm very interesting.

The recorder will erase a tape if I try getting it into the so called record mode.

The superimpose option seems logical to me by how it's acting when I go into that mode.

The machine will play existing recordings and it also seems to get the input I feed it. The problem is that the input isn't getting onto the tape. It will erase an existing tape just fine, in fact, quite well, so I'm sure the erase head is working. Just, it seems almost as if the amplifier isn't sending the record signal to the head.

Also, coulf these hydroscopic caps be causing the record problem?

I'll definately check their resistance, maybe even with my megger.

I guess a few megs might throw some bias around a bit, who knows.
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Old 10th May 2003, 04:21 PM   #7
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Default If it's not the caps....

The fact that it erases is good news. It means thet the bias oscillator is working. The fault is therefore in the record-amplifier.
Costs were often cut by making some of the circuitry common to record and playback. This meant there was more than a little switching involved. Check the switches that activate when you change from playback to record. They are probably quite dirty, and could be corroded. It is unwise to try to individually clean or retension contacts. Best to try to blow away dust, and if you have some, apply a little switch-cleaner spray, then repeatedly operate the switches.

Good luck
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Old 10th May 2003, 07:28 PM   #8
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Is this recorder a TK60 by any chance? The TK60 was the first stereo recorder released by Grundig over here (the UK) in the early '60s.

If it is, or a similar model, it may have two power valves in the bias oscillator stage - Grundig sometimes used an EL95 for generating the erase voltage, and a seperate EL95 for providing the bias voltage. If there is a fault with the latter stage then the recorder will erase alright, but without the bias voltage recording will not be possible, you might get very faint distorted sound at best when you try to record.
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Old 10th May 2003, 07:44 PM   #9
dhaen is offline dhaen  Europe
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Bournville,

You remember these better than me, I think
I hadn't realised / remembered the dual EL95's in this model.

Duo said it came out of a console, so it probably hasn't got a normal model number.

Duo,

A picture might help, as might the valve lineup.

Cheers,
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Old 10th May 2003, 11:33 PM   #10
Duo is offline Duo  Canada
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Okay, the tube compliment is:
2X ECC81
2X EF86
1X EL95

Here are some pictures.
Attached Images
File Type: jpeg grundigface.jpeg (18.8 KB, 213 views)
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