Grundig C480 cassette record din socket - UK Vintage Radio Repair and Restoration Discussion Forum

terrybull · 1st Apr 2020, 8:30 pm

I have a C480 and am struggling to know what the 7 pin din on the side connections are. I’m hoping for line level out. Or is this just for stereo microphone in. Can anyone advise please.

DMcMahon · 1st Apr 2020, 9:41 pm

Hello Terry,

German Service manual is attached, only one I can easily find.

Second to last page shows the C 480 electrical schematic.

Pins 1 and 4 as usual are the 2 stereo inputs. Pins 3 & 5 as usual are the 2 stereo high impedance outputs, with pin 2 as usual being 0V/ground.

Unsure about pin 8, sometimes on multi pin DIN for microphones it is the Electret microphone supply voltage.

Also not sure about pin 7, maybe Remote Motor Stop/Pause.

Shame it has only got internal mono output.

David

terrybull · 2nd Apr 2020, 8:12 am

Thank you David. That helps.

julie_m · 2nd Apr 2020, 4:55 pm

Pin 7 is connected, through a contact in the play/record (or wiedergabe / aufnahme

) switch, to the base of an NPN transistor which switches the motor; there is a pull-up resistor so this transistor is normally turned on. Pin 6 is grounded.

It looks as though applying a short from pin 6 to pin 7 while the machine is in record mode would stop the motor without affecting the electronics, so this is probably for a remote switch on the mic.

Pin 8 seems to be connected to supply + to power an electret mic.

AndiiT · 4th Apr 2020, 5:10 pm

Hi, i would echo what others have said about the DIN socket connections however - This looks like a Mono machine from the circuit provided (unless I have missed something) the DIN socket is wired similarly to some ITT/KB models I have encountered.

Pin 2, as always is ground
Pin 1 is low level input, for an external microphone or other equipment producing signal levels to DIN standard so around 1mV to 5mV in to 47K
Pin 4 is not connected(?)
Pins 5 and 3 are line level output to an external amplifier on PLAYBACK only, this signal will be in the order of 500mV to 1.5V into around 100K or more
Pins 5 and 3 may also accept line level inputs during record however I haven't looked that closely at the circuit.
Pin 6 is also ground and tied to pin 2 (see later)
Pin 7 will be some kind of motor stop/start signal; the simplest way of doing this would be to have a switch, in series with the motor supply, which is operated by insertion of the Microphone DIN plug, I don't think that your machine uses this technique though despite having a switched socket shown on the diagram.
Pin 8 is most likely for an external DC power supply in conjunction with pin 6

Regards

Andrew

terrybull · 4th Apr 2020, 5:49 pm

Thanks for the further info both Julie m and Andrew. I am transcribing some interviews I made 40 odd years ago using a basic Phillips cassette recorder. In the absence of a proper dictation player that rewinds a second or 2 on pause I’m putting these on the computer and playing back with VLC. I do have a stereo cassette deck somewhere but this Grundig is a well made unit and is more convenient. I just need line level out to direct connect to the computer as using a microphone connected to the laptop to record the cassette speaker is a little crude.
I agree with a Andrew that although this is emblazoned ‘stereo automatic’ there seems no evidence of how this is stereo.

TonyDuell · 4th Apr 2020, 5:58 pm

Looking at the service manual it appears that the C450 and C460 are mono machines but that the C480 does have 2 channels of record/playback amplifiers (alhough only one intenral speaker and power amplfiier) and thus is a stereo machine.

Another thing.... Some time ago I bought a load of 'tape recorder microphones' mainly to get a Philips one I wanted (and also the right one for a little Sanyo portable reel-to-reel machine). Amongst them was one with a remote control switch on the body with a cable ending in a 7 pin DIN plug with a much longer than normal metal casing round the pins. I wonder if that was to operate a switch in a machine such as this one (to allow the remote switch to work) while a normal DIN plug put in the socket wouldn't. so you could use normal audio cables for record/playback.

DMcMahon · 4th Apr 2020, 11:07 pm

Yes the C480 is one of those strange machines with stereo inputs/outputs but only a mono output power amp stage, rationale behind this is unknown to me.

I am sure pin 4 is used for right channel low level record input. Agree about pins 3 & 5 can also be high level inputs on record.

emeritus · 4th Apr 2020, 11:51 pm

I don't know how large the stereo version is, but perhaps it isn't big enough to space two speakers far enough apart to get an adequate stereo effect. I have a Sony radio with a single speaker and a stereo headphone socket, and a Philips stereo cassette deck with line, mic, and headphone sockets, bu no internal speaker.

julie_m · 5th Apr 2020, 11:58 am

The reel-to-reel Uher 4200/4400 machines were stereo recorders but only had a single speaker for mono playback. For a machine intended primarily as a field recorder, this was less of a limitation; the actual intended playback would be on a stereo machine in a studio, and it's more important just to know you have actually captured something; the two meter needles behaving differently are your clue that it's two distinct channels of sound.

TonyDuell · 5th Apr 2020, 2:38 pm

Uher carried that idea on into cassette recorders. My CR210 is a fully stereo machine but with just one internal speaker. It does have 2 power amplifiers though so can drive a pair of speakers or stereo headphones.

And of course some Revox reel-to-reel machines like my G36 have only a single internal power amplifier/speaker. Fully stereo up to that point though.

DMcMahon · 5th Apr 2020, 3:43 pm

Quote:

Originally Posted by emeritus

I don't know how large the stereo version is, but perhaps it isn't big enough to space two speakers far enough apart to get an adequate stereo effect. I have a Sony radio with a single speaker and a stereo headphone socket, and a Philips stereo cassette deck with line, mic, and headphone sockets, bu no internal speaker.

I do not know if that would be the reason, one could argue that most if not all stereo music machines with fitted internal stereo speakers, that they would not be far enough apart to give a proper stereo soundstage image, although still providing good sound.

Also maybe a consideration of achieving good sound without increasing the unit size, i.e. mono sound through a good size speaker may sound better than stereo from 2 smaller speakers.

It could also be done for cost considerations and practical consideration of keeping the size compact. I think there are some larger examples such as the older Grundig Reel to Reel TK 55.

1st Apr 2020, 8:30 pm	#1
terrybull Octode Join Date: Jan 2011 Location: Southwell, Nottinghamshire, UK. Posts: 1,780	Grundig C480 cassette record din socket I have a C480 and am struggling to know what the 7 pin din on the side connections are. I’m hoping for line level out. Or is this just for stereo microphone in. Can anyone advise please. Attached Thumbnails

2nd Apr 2020, 8:12 am	#3
terrybull Octode Join Date: Jan 2011 Location: Southwell, Nottinghamshire, UK. Posts: 1,780	Re: Grundig C480 cassette record din socket Thank you David. That helps.

2nd Apr 2020, 4:55 pm	#4
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Grundig C480 cassette record din socket Pin 7 is connected, through a contact in the play/record (or wiedergabe / aufnahme ) switch, to the base of an NPN transistor which switches the motor; there is a pull-up resistor so this transistor is normally turned on. Pin 6 is grounded. It looks as though applying a short from pin 6 to pin 7 while the machine is in record mode would stop the motor without affecting the electronics, so this is probably for a remote switch on the mic. Pin 8 seems to be connected to supply + to power an electret mic. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

4th Apr 2020, 5:10 pm	#5
AndiiT Octode Join Date: Aug 2005 Location: Saltburn-East, Cleveland, UK. Posts: 1,786	Re: Grundig C480 cassette record din socket Hi, i would echo what others have said about the DIN socket connections however - This looks like a Mono machine from the circuit provided (unless I have missed something) the DIN socket is wired similarly to some ITT/KB models I have encountered. Pin 2, as always is ground Pin 1 is low level input, for an external microphone or other equipment producing signal levels to DIN standard so around 1mV to 5mV in to 47K Pin 4 is not connected(?) Pins 5 and 3 are line level output to an external amplifier on PLAYBACK only, this signal will be in the order of 500mV to 1.5V into around 100K or more Pins 5 and 3 may also accept line level inputs during record however I haven't looked that closely at the circuit. Pin 6 is also ground and tied to pin 2 (see later) Pin 7 will be some kind of motor stop/start signal; the simplest way of doing this would be to have a switch, in series with the motor supply, which is operated by insertion of the Microphone DIN plug, I don't think that your machine uses this technique though despite having a switched socket shown on the diagram. Pin 8 is most likely for an external DC power supply in conjunction with pin 6 Regards Andrew

4th Apr 2020, 5:49 pm	#6
terrybull Octode Join Date: Jan 2011 Location: Southwell, Nottinghamshire, UK. Posts: 1,780	Re: Grundig C480 cassette record din socket Thanks for the further info both Julie m and Andrew. I am transcribing some interviews I made 40 odd years ago using a basic Phillips cassette recorder. In the absence of a proper dictation player that rewinds a second or 2 on pause I’m putting these on the computer and playing back with VLC. I do have a stereo cassette deck somewhere but this Grundig is a well made unit and is more convenient. I just need line level out to direct connect to the computer as using a microphone connected to the laptop to record the cassette speaker is a little crude. I agree with a Andrew that although this is emblazoned ‘stereo automatic’ there seems no evidence of how this is stereo.

4th Apr 2020, 5:58 pm	#7
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Grundig C480 cassette record din socket Looking at the service manual it appears that the C450 and C460 are mono machines but that the C480 does have 2 channels of record/playback amplifiers (alhough only one intenral speaker and power amplfiier) and thus is a stereo machine. Another thing.... Some time ago I bought a load of 'tape recorder microphones' mainly to get a Philips one I wanted (and also the right one for a little Sanyo portable reel-to-reel machine). Amongst them was one with a remote control switch on the body with a cable ending in a 7 pin DIN plug with a much longer than normal metal casing round the pins. I wonder if that was to operate a switch in a machine such as this one (to allow the remote switch to work) while a normal DIN plug put in the socket wouldn't. so you could use normal audio cables for record/playback.

4th Apr 2020, 11:07 pm	#8
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,600	Re: Grundig C480 cassette record din socket Yes the C480 is one of those strange machines with stereo inputs/outputs but only a mono output power amp stage, rationale behind this is unknown to me. I am sure pin 4 is used for right channel low level record input. Agree about pins 3 & 5 can also be high level inputs on record.

4th Apr 2020, 11:51 pm	#9
emeritus Dekatron Join Date: Jan 2012 Location: Brentwood, Essex, UK. Posts: 5,339	Re: Grundig C480 cassette record din socket I don't know how large the stereo version is, but perhaps it isn't big enough to space two speakers far enough apart to get an adequate stereo effect. I have a Sony radio with a single speaker and a stereo headphone socket, and a Philips stereo cassette deck with line, mic, and headphone sockets, bu no internal speaker.

5th Apr 2020, 11:58 am	#10
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Grundig C480 cassette record din socket The reel-to-reel Uher 4200/4400 machines were stereo recorders but only had a single speaker for mono playback. For a machine intended primarily as a field recorder, this was less of a limitation; the actual intended playback would be on a stereo machine in a studio, and it's more important just to know you have actually captured something; the two meter needles behaving differently are your clue that it's two distinct channels of sound. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

5th Apr 2020, 2:38 pm	#11
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Grundig C480 cassette record din socket Uher carried that idea on into cassette recorders. My CR210 is a fully stereo machine but with just one internal speaker. It does have 2 power amplifiers though so can drive a pair of speakers or stereo headphones. And of course some Revox reel-to-reel machines like my G36 have only a single internal power amplifier/speaker. Fully stereo up to that point though.