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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 6th Dec 2004, 3:47 pm   #1
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Default Grundig TK5 Recording Problems

I have recently aquired a microphone but when i record using it it is not deleting the origanal recording on the tape any ideas anyone?I hear both the recording I make and what was origanly on the tape.
Old 6th Dec 2004, 4:08 pm   #2
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Default Re: Grundig TK5 Recording Problems

I don't know this machine, but the Ferrographs have an erase link. Is there something like this on your Grundig (no idea if there is, or where it could be!)

Hope this is of some help!

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Old 6th Dec 2004, 4:29 pm   #3
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Default Re: Grundig TK5 Recording Problems


This fault is not uncommon and is down to age of tapes/machine and /or dirty heads. Old machines such as the TK5 which have been picked up at boot sales after years of disuse are most likely to show this fault.

It could be down to a dirty recording/erasing head. Try cleaning it with a soft brush or a clean tissue. Don't use fluids.

It's also quite likely your tape is knackered. Engineers of 40 years ago would say the previous recording is too deeply imprinted on the tape ( close to the limits of level, as it was called ). To cure the problem you need what was called a 'bulk eraser' but you'll be unlikely to find one these days. As Sam said, certain Ferrographs had an erase link which is much the same thing - but the TK5 is too basic to have such a device beyond it's normal erase/record facility.

Another possible cause may be misaligned heads, but this is mosy unlikely.

I suggest cleaning the heads and running the tape through it until it is totally erased ( if it's capable of doing so ) but with no mic connected. Failing that obtain another tape and dump your original.

We must remember that recording equipment such as this is ancient and thus will deteriorate. Heads get a build up of oxide particles from the tapes, heads need demagnetising from time to time .... and magnetic tapes only have a certain life expectancy. Most old tapes from the 50s and 60s which turn up today are only fit for the dustbin I'm afraid.
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Old 6th Dec 2004, 4:50 pm   #4
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Default Re: Grundig TK5 Recording Problems

More information here:-

Regards, Mick.

Last edited by Paul Stenning; 29th Dec 2004 at 2:04 pm.
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Old 8th Dec 2004, 9:29 am   #5
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Default Re: Grundig TK5 Recording Problems

Sounds like no bias reaching the erase head, apart from checking the head is clean would suggest possible dirt on the record/playback system switch, as the bias is fed through this when in the record position. Also check condition of caps as the machine is quite old. There is of
course an outside chance that the head itself is open circuit.
Good luck
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Old 16th Dec 2004, 12:23 am   #6
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Default Re: Grundig TK5 Recording Problems

Hi Leverman
The other chaps seem to have this one well covered!
If the machine still doesn't work satisfactorily after a good clean the bias may be weak, possibly caused by a low emmission oscillator valve.
Inside are two EL42 valves. One is used for the bias oscillator(supplies the erase and record bias signal) and the other is the audio output valve. If you swap them round and the erase then works the fault is probably down to a faulty valve. Much more likely however is that it is down to those horrible brown Wima capacitors(look just like toffees, and are just about as much usel!)
If you have access to a multimeter (or even better an oscilloscope) the current through the erase head can be checked in the following way:
One of the connections to the erase head is strapped to chassis. Break this link and insert a 100 ohm resistor. Measure the ac voltage across the resistor. There should be about 100 millivolts (0.1 volts). A 'scope is particularly useful here.
If you are confident with a meter and soldering iron etc. and need to delve deeper,drop me a PM with your e-mail address and I will send you a copy of the circuit diagram etc.
Good luck
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Old 16th Dec 2004, 8:00 am   #7
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Default Re: Grundig TK5 Recording Problems

Hi Gents, please remember the old caution about NOT checking head continuity with an ohmmeter as it will magnetise the heads and cause distortion.

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