Grundig TK20 line out wiring? - UK Vintage Radio Repair and Restoration Discussion Forum

quad2fan · 29th Apr 2012, 4:50 pm

Hi folks!

I have a Grundig TK20 which - after replacing the rubber belts - working fine and sounding as it should (touch wood!). I have a few tapes I'd like to transfer to digital to preserve them. I realise buying/using a much better quality deck would likely result in better sound quality, but there's something nice about playing back the tapes on the deck they were originally recorded on.

I don't suppose anyone has the DIN pin-outs and knows of the suitable output socket to use? I did have a look at the manual but it wasn't altogether clear (well at least not to me!). I did try to lash one up a while back but got massive levels of hum so I obviously did something wrong.

Any help would be greatly appreciated

Thanks,

- John

julie_m · 29th Apr 2012, 5:08 pm

Pin 2 is always common. The signal may be on pin 3 or (less commonly) pin 1 -- try it both ways.

Breton56 · 29th Apr 2012, 6:06 pm

From memory,pin 1 is input,pin 3 is output,pin 2 common (ground).

AndiiT · 29th Apr 2012, 10:27 pm

Hi,
On the DIN socket marked output, Pin 1 is the high Level output direct from the speaker, Pin 3 is the low (line) level output and Pin 2 is common or ground.

There is also a low level output, identical to that on Pin 3 of the "Output" socket, available on Pin 3 of the Diode socket; this output is only present on playback unlike the one on the output socket which can be used for 'monitoring' during recording.

The volume control will affect both high and low level outputs so will have an effect on the subsequent recordings that you transfer over to your PC.

Regards
Andrew

quad2fan · 29th Apr 2012, 11:39 pm

MANY thanks guys - much appreciated indeed! Hopefully I'll be able to wire a lead up at some point this week and give it a go. I take it I can just common up the signal, and the ground at the Grundig end of the interconnect? Or should I stick with a single/mono interconnect?

Thanks again.

- John

Tractorfan · 30th Apr 2012, 9:46 am

Hi,
I've got a TK120 and it came with a cable for line in recordings. The DIN plug has a tiny resistor & a capacitor inside it as a sort of attenuator. If you put a signal straight in, it might overload the pre-amp. Although, having said that, I've had no problems using ordinary DIN leads.
Strangely, mine is still running on the original belt.
Oops! Just spotted that yours is a TK20

Cheers, Pete

PS What's an "interconnect"

. Is it anything like a DIN lead?

Tractorfan · 30th Apr 2012, 1:24 pm

Hi,
If you common up the signal and the ground, that would be a short circuit and it won't work. Or did I misunderstand?
Cheers, Pete

julie_m · 30th Apr 2012, 3:27 pm

What you want to do is connect a length of single-core, shielded cable with the inner core to both the "tip" and "middle" contacts of a 3.5 mm stereo plug, and the outer braid to the body. At the tape recorder end, connect the braid to DIN plug pin 2 and the inner core to pin 3. Insert the 3.5 mm. plug into the blue "line in" socket on your sound card and the 3-pin DIN plug into the Grundig. Fire up Audacity, and away you go!

If you cannot get this to work at all, try with the inner core to pin 1.

NB. Watch the levels! You want to keep the playback volume up so the signal is well above the noise floor; but if it goes into distortion, it will ruin the whole recording. Be sure to listen back to the loudest and quietest passages again through a decent pair of headphones.

quad2fan · 30th Apr 2012, 7:44 pm

Quote:

Originally Posted by Tractorfan

Hi,
If you common up the signal and the ground, that would be a short circuit and it won't work. Or did I misunderstand?
Cheers, Pete

Yep that wouldn't work. What I meant was that one end (the TK20 DIN end) is obviously going to be mono, but the other end of the interconnect (wire) has two phono plugs (stereo pair). So I assume I connect both earth screens together and solder to the DIN pin, and the L & R signal also get soldered together, and attached to the other DIN pin.

However I have decided now that I'll just use a single (mono) interconnect though to keep things simple - I can sort the rest out in Adobe Audition afterwards.

- John

quad2fan · 30th Apr 2012, 7:45 pm

Quote:

Originally Posted by ajs_derby

What you want to do is connect a length of single-core, shielded cable with the inner core to both the "tip" and "middle" contacts of a 3.5 mm stereo plug, and the outer braid to the body. At the tape recorder end, connect the braid to DIN plug pin 2 and the inner core to pin 3. Insert the 3.5 mm. plug into the blue "line in" socket on your sound card and the 3-pin DIN plug into the Grundig. Fire up Audacity, and away you go!

If you cannot get this to work at all, try with the inner core to pin 1.

NB. Watch the levels! You want to keep the playback volume up so the signal is well above the noise floor; but if it goes into distortion, it will ruin the whole recording. Be sure to listen back to the loudest and quietest passages again through a decent pair of headphones.

Thanks for the tips - I'll be using phono plugs though for my USB soundcard not the 3.5mm stereo plugs. Going to use a mono cable to keep it simple now also.

Cheers,

- John

quad2fan · 30th Apr 2012, 7:46 pm

Quote:

Originally Posted by Tractorfan

Hi,
I've got a TK120 and it came with a cable for line in recordings. The DIN plug has a tiny resistor & a capacitor inside it as a sort of attenuator. If you put a signal straight in, it might overload the pre-amp. Although, having said that, I've had no problems using ordinary DIN leads.
Strangely, mine is still running on the original belt.
Oops! Just spotted that yours is a TK20

Cheers, Pete

PS What's an "interconnect"

. Is it anything like a DIN lead?

Interesting about the resistor/capacitor attenuator - I believe the manual makes reference to a similar lead for the TK20 which was available. Need to find my service manual and take another look.

AndiiT · 30th Apr 2012, 8:32 pm

Quote:

Originally Posted by Tractorfan

......The DIN plug has a tiny resistor & a capacitor inside it as a sort of attenuator. .....

Hi,
The resistor is probably connected in series with Pin 1 of the DIN plug and will be around or between 470K ohms to 1M5; this would have reduced the signal from the output of the source equipment to a level suitable for feeding in to the recorders 'Diode' input, which requires a signal of around 2 to 5mV. (This is presuming a high impedance output with a level of around 0.5 to 1Volt from the source equipment)

The capacitor would probably be in the order of around 35pF and would usually only be fitted if the screened lead was over 3 or more metres in length.

Regards

Andrew

Tractorfan · 30th Apr 2012, 9:36 pm

Hi,
The lead is only about a metre long and was supplied with bare ends. I was thinking that the resistor/cap combo was to take an output from the extension loudspeaker sockets of a radio and reduce it a bit to the 'diode' input of the tape recorder. I imagine that this would be a common practice in the sixties as few domestic radios would have a line-out connection and recording "Pick Of The Pops" was a popular pastime. (My brother just stuck the mic in front of the speaker.)
Cheers, Pete

julie_m · 30th Apr 2012, 9:45 pm

If your soundcard has phono sockets, then wire two phono plugs together and come from pin 3 (or maybe 1 if 3 doesn't work) of the DIN plug, with grounds to pin 2. You want it in 2 channels anyway to burn to CD; so you might as well record on both channels together, and skip the (disk-access heavy) step of converting one channel to two.

DOFFERY · 1st May 2012, 1:41 pm

Pete,
The reason for the attenuated lead for the TK 120 was exactly that, there was only one din input on the recorder & the attenuation was required to reduce the input signal to that of the mic. input.

With the lead for the TK 20 , as rightly mentioned there were few radios with a low level output & I still have items(diode units) that were to be fitted to radios to reduce the signal to a low level, the Grundig leads were to fulfill the same procedure,plus other functions.

Colin.

29th Apr 2012, 4:50 pm	#1
quad2fan Retired Dormant Member Join Date: Sep 2008 Location: Basingstoke, Hampshire, UK. Posts: 52	Grundig TK20 line out wiring? Hi folks! I have a Grundig TK20 which - after replacing the rubber belts - working fine and sounding as it should (touch wood!). I have a few tapes I'd like to transfer to digital to preserve them. I realise buying/using a much better quality deck would likely result in better sound quality, but there's something nice about playing back the tapes on the deck they were originally recorded on. I don't suppose anyone has the DIN pin-outs and knows of the suitable output socket to use? I did have a look at the manual but it wasn't altogether clear (well at least not to me!). I did try to lash one up a while back but got massive levels of hum so I obviously did something wrong. Any help would be greatly appreciated Thanks, - John

29th Apr 2012, 5:08 pm	#2
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Grundig TK20 line out wiring? Pin 2 is always common. The signal may be on pin 3 or (less commonly) pin 1 -- try it both ways. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

29th Apr 2012, 6:06 pm	#3
Breton56 Triode Join Date: Jul 2011 Location: Mumby,Lincolnshire Posts: 45	Re: Grundig TK20 line out wiring? From memory,pin 1 is input,pin 3 is output,pin 2 common (ground).

29th Apr 2012, 10:27 pm	#4
AndiiT Octode Join Date: Aug 2005 Location: Saltburn-East, Cleveland, UK. Posts: 1,786	Re: Grundig TK20 line out wiring? Hi, On the DIN socket marked output, Pin 1 is the high Level output direct from the speaker, Pin 3 is the low (line) level output and Pin 2 is common or ground. There is also a low level output, identical to that on Pin 3 of the "Output" socket, available on Pin 3 of the Diode socket; this output is only present on playback unlike the one on the output socket which can be used for 'monitoring' during recording. The volume control will affect both high and low level outputs so will have an effect on the subsequent recordings that you transfer over to your PC. Regards Andrew

29th Apr 2012, 11:39 pm	#5
quad2fan Retired Dormant Member Join Date: Sep 2008 Location: Basingstoke, Hampshire, UK. Posts: 52	Re: Grundig TK20 line out wiring? MANY thanks guys - much appreciated indeed! Hopefully I'll be able to wire a lead up at some point this week and give it a go. I take it I can just common up the signal, and the ground at the Grundig end of the interconnect? Or should I stick with a single/mono interconnect? Thanks again. - John

30th Apr 2012, 9:46 am	#6
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,184	Re: Grundig TK20 line out wiring? Hi, I've got a TK120 and it came with a cable for line in recordings. The DIN plug has a tiny resistor & a capacitor inside it as a sort of attenuator. If you put a signal straight in, it might overload the pre-amp. Although, having said that, I've had no problems using ordinary DIN leads. Strangely, mine is still running on the original belt. Oops! Just spotted that yours is a TK20 Cheers, Pete PS What's an "interconnect" . Is it anything like a DIN lead? __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

30th Apr 2012, 1:24 pm	#7
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,184	Re: Grundig TK20 line out wiring? Hi, If you common up the signal and the ground, that would be a short circuit and it won't work. Or did I misunderstand? Cheers, Pete __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

30th Apr 2012, 3:27 pm	#8
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Grundig TK20 line out wiring? What you want to do is connect a length of single-core, shielded cable with the inner core to both the "tip" and "middle" contacts of a 3.5 mm stereo plug, and the outer braid to the body. At the tape recorder end, connect the braid to DIN plug pin 2 and the inner core to pin 3. Insert the 3.5 mm. plug into the blue "line in" socket on your sound card and the 3-pin DIN plug into the Grundig. Fire up Audacity, and away you go! If you cannot get this to work at all, try with the inner core to pin 1. NB. Watch the levels! You want to keep the playback volume up so the signal is well above the noise floor; but if it goes into distortion, it will ruin the whole recording. Be sure to listen back to the loudest and quietest passages again through a decent pair of headphones. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

30th Apr 2012, 9:36 pm	#13
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,184	Re: Grundig TK20 line out wiring? Hi, The lead is only about a metre long and was supplied with bare ends. I was thinking that the resistor/cap combo was to take an output from the extension loudspeaker sockets of a radio and reduce it a bit to the 'diode' input of the tape recorder. I imagine that this would be a common practice in the sixties as few domestic radios would have a line-out connection and recording "Pick Of The Pops" was a popular pastime. (My brother just stuck the mic in front of the speaker.) Cheers, Pete __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

30th Apr 2012, 9:45 pm	#14
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Grundig TK20 line out wiring? If your soundcard has phono sockets, then wire two phono plugs together and come from pin 3 (or maybe 1 if 3 doesn't work) of the DIN plug, with grounds to pin 2. You want it in 2 channels anyway to burn to CD; so you might as well record on both channels together, and skip the (disk-access heavy) step of converting one channel to two. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

1st May 2012, 1:41 pm	#15
DOFFERY Retired Dormant Member Join Date: Aug 2004 Location: Blackpool, Lancashire, UK. Posts: 1,488	Re: Grundig TK20 line out wiring? Pete, The reason for the attenuated lead for the TK 120 was exactly that, there was only one din input on the recorder & the attenuation was required to reduce the input signal to that of the mic. input. With the lead for the TK 20 , as rightly mentioned there were few radios with a low level output & I still have items(diode units) that were to be fitted to radios to reduce the signal to a low level, the Grundig leads were to fulfill the same procedure,plus other functions. Colin.