Hitachi SDT 7785 Music Centre DIN to Phono - UK Vintage Radio Repair and Restoration Discussion Forum

jonnyburstow · 24th Jun 2018, 8:20 pm

Hi there,

I'm a complete audio novice so I apologise if I'm not clear or get any terminology wrong.

We recently picked up a Hitachi Music Centre for free to play our vinyl record collection. The sound quality is wonderful and we're really pleased with it.

One thing I would like to know is if I can connect an external device (my phone, laptop etc) to the centre via phono?

The only inputs i can see are DIN and I have tried a DIN to Phono but that hasn't worked.

The tape player hasn't worked since we picked it up but the record player and radio has worked great.

Any help or advice would be really appreciated.

Many thanks
Jonny

Dai Corner · 24th Jun 2018, 11:55 pm

You don't say how many pins your DIN socket has, but it's quite likely to be a 5-pin one which caters for both inputs and outputs. If you haven't done so already, get a DIN to 4 phono lead and experiment.

http://www.cabling4less.co.uk/produc..._stereo_inout/

(An example, not a recommendation)

Grubhead · 25th Jun 2018, 12:18 am

I should imagine the belts on the tape player have perished so will need replacing. You can get cheap assorted belt sets from eBay.

If the unit has an AUX Din it should play back anything, with the right set of leads.

Nickthedentist · 25th Jun 2018, 10:29 am

Hello, and welcome.

That's a very nice music centre indeed, and the sound quality it's capable of delivering will be streets ahead of anything modern unless you're willing to pay for a proper hifi separates system.

Please could you post good photos of the socket, and input selector buttons on the front (which will be marked phono, tape etc.

It could be that the socket is only an output, not an input.

Nick.

Nickthedentist · 25th Jun 2018, 10:32 am

EDIT: As I suspected, there's no auxillary input channel as far as I can see: http://bilder.hifi-forum.de/medium/5...chi_703627.jpg

You might be best using one of those little adaptors that people used to connect their MP3 players to car cassette players. I suspect this would work even if the cassette section is otherwise not working.

https://i.ebayimg.com/images/g/0QQAA...DkC/s-l640.jpg

Nick.

ben · 27th Jun 2018, 12:36 am

Nick, I'm fairly sure that I've seen music centres with no dedicated AUX input but which allow the input signal to pass when in TAPE mode (i.e. for dubbing). Could this be the case here I wonder.

'LIVEWIRE?' · 27th Jun 2018, 8:07 am

Two points. (1) The cassette adaptor should indeed work even if the cassette recorder doesn't run, provided the recorder is powered and the Play button can be depressed -these work by electro-magnetic coupling between a head in the adapter, and the rec/PB head in the recorder. (2) The 5-pin DIN socket in the music centre is almost certainly wired to the standard convention so a DIN to Phono adapter wired to pins 1, 4 & 2 of it's DIN plug should work, although the cassette recorder may have to be set to record mode. This would obviously mean that, with a working tape deck, recordings could be made from an external source (as designed), so internal modifications would be needed to create a true 'aux-in' facility.

Nickthedentist · 27th Jun 2018, 8:08 am

Quote:

Originally Posted by ben

Nick, I'm fairly sure that I've seen music centres with no dedicated AUX input but which allow the input signal to pass when in TAPE mode (i.e. for dubbing). Could this be the case here I wonder.

You may well be right, Ben. Anyone got the circuit diagram?

Nickthedentist · 27th Jun 2018, 8:09 am

Jonny,

I see you have the user instructions.

Is there anything in there that's pertinent to this?

Nick

Edward Huggins · 27th Jun 2018, 9:19 am

One can understand why in these mid-1970s Music Centres, AUX inputs were sometimes ommited. There were no CD player inputs to consider in those days and R2R was definitely on the wane as cassette technology was reaching its peak.

'LIVEWIRE?' · 27th Jun 2018, 11:32 am

When I had a Sharp SG500E, which only had the standard 5-pin DIN socket, I was able to play external sources (CD Player & second tape deck) through the DIN socket. To make switching sources easy, I made up a switch box, using a 4-way push-button assembly, then plugged in the external audio devices. The box connected to the 500E via a 5-pin DIN plug, and good quality sound was available from the CD Player, etc. I no longer have any service info. for the 500E, but, IIRC, the DIN socket was wired to the usual convention.

Dai Corner · 27th Jun 2018, 2:52 pm

Just a hunch, but try depressing the Record button with a source connected to the DIN socket.

John123 · 29th Jun 2018, 12:51 am

Looks like it's a 'Power Assisted' tape deck, so the bad news is it might not be possible to engage 'record and play' if the belts have perished. The good news is, as mentioned above, it might be possible to simply depress the 'record' button for monitoring. You may have to insert a cassette for it to do anything at all, so just make sure it's one where the write protect tabs have been removed beforehand (i.e. a blank cassette).

If still no joy don't force any of the buttons as it may cause damage to the mechanism. You will have to have the belts replaced to get anything more from it.

If, however, you can get the tape deck into record mode, you should be able to feed a signal into the mic socket. Just make sure the record level is turned up, and not peaking too far into the red on the VU's.

toshiba tony · 29th Jun 2018, 1:56 am

Not nitpicking John, surely you mean make sure tab is present.

Herald1360 · 29th Jun 2018, 10:01 am

Quote:

Originally Posted by John123

... so just make sure it's one where the write protect tabs have not? been removed beforehand (i.e. a blank cassette).

Perhaps?

'LIVEWIRE?' · 29th Jun 2018, 10:04 am

IIRC, when Ihad to SG500E, I didn't have to put the cassette deck into record mode to listen to external devices, but Hitachi may have wired their DIN socket differently to Sharp.

John123 · 30th Jun 2018, 12:28 am

Quote:

Originally Posted by toshiba tony

Not nitpicking John, surely you mean make sure tab is present.

Yes that! I shouldn't post so late at night haha

jonnyburstow · 9th Aug 2018, 11:29 am

Hello everyone, firstly let me apologise for not returning your messages sooner.

I will now spend some time going through your advice and will try to answer as many questions as possible and give these tips a try.

I have just tried a DIN to 3.5 jack and nothing has happened but I will try with a tape in and also with the record button on and off. I'll report back with my findings.

Once again, thanks so much for taking your time to help me.

Jonny

Edward Huggins · 9th Aug 2018, 12:56 pm

So welcome back. Is it a 5 pin DIN?

cooperman · 9th Aug 2018, 3:42 pm

Just a note about Phono to DIN adaptors. I purchased such an item recently and I found that it was wired for a MIDI interface rather than the way DIN plugs were wired for audio systems back in the 70s. Needless to say it did not work properly - I had to snip the plug and rewire.

24th Jun 2018, 8:20 pm	#1
jonnyburstow Retired Dormant Member Join Date: Jun 2018 Location: Reigate, Surrey, UK. Posts: 2	Hitachi SDT 7785 Music Centre DIN to Phono Hi there, I'm a complete audio novice so I apologise if I'm not clear or get any terminology wrong. We recently picked up a Hitachi Music Centre for free to play our vinyl record collection. The sound quality is wonderful and we're really pleased with it. One thing I would like to know is if I can connect an external device (my phone, laptop etc) to the centre via phono? The only inputs i can see are DIN and I have tried a DIN to Phono but that hasn't worked. The tape player hasn't worked since we picked it up but the record player and radio has worked great. Any help or advice would be really appreciated. Many thanks Jonny Attached Thumbnails

24th Jun 2018, 11:55 pm	#2
Dai Corner Hexode Join Date: Oct 2016 Location: Newport, South Wales, UK. Posts: 278	Re: Hitachi SDT 7785 Music Centre DIN to Phono You don't say how many pins your DIN socket has, but it's quite likely to be a 5-pin one which caters for both inputs and outputs. If you haven't done so already, get a DIN to 4 phono lead and experiment. http://www.cabling4less.co.uk/produc..._stereo_inout/ (An example, not a recommendation)

25th Jun 2018, 12:18 am	#3
Grubhead Heptode Join Date: Dec 2016 Location: Sheffield, South Yorkshire, UK. Posts: 539	Re: Hitachi SDT 7785 Music Centre DIN to Phono I should imagine the belts on the tape player have perished so will need replacing. You can get cheap assorted belt sets from eBay. If the unit has an AUX Din it should play back anything, with the right set of leads.

25th Jun 2018, 10:29 am	#4
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,859	Re: Hitachi SDT 7785 Music Centre DIN to Phono Hello, and welcome. That's a very nice music centre indeed, and the sound quality it's capable of delivering will be streets ahead of anything modern unless you're willing to pay for a proper hifi separates system. Please could you post good photos of the socket, and input selector buttons on the front (which will be marked phono, tape etc. It could be that the socket is only an output, not an input. Nick.

25th Jun 2018, 10:32 am	#5
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,859	Re: Hitachi SDT 7785 Music Centre DIN to Phono EDIT: As I suspected, there's no auxillary input channel as far as I can see: http://bilder.hifi-forum.de/medium/5...chi_703627.jpg You might be best using one of those little adaptors that people used to connect their MP3 players to car cassette players. I suspect this would work even if the cassette section is otherwise not working. https://i.ebayimg.com/images/g/0QQAA...DkC/s-l640.jpg Nick.

27th Jun 2018, 12:36 am	#6
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Hitachi SDT 7785 Music Centre DIN to Phono Nick, I'm fairly sure that I've seen music centres with no dedicated AUX input but which allow the input signal to pass when in TAPE mode (i.e. for dubbing). Could this be the case here I wonder. __________________ Regards, Ben.

27th Jun 2018, 8:07 am	#7
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Hitachi SDT 7785 Music Centre DIN to Phono Two points. (1) The cassette adaptor should indeed work even if the cassette recorder doesn't run, provided the recorder is powered and the Play button can be depressed -these work by electro-magnetic coupling between a head in the adapter, and the rec/PB head in the recorder. (2) The 5-pin DIN socket in the music centre is almost certainly wired to the standard convention so a DIN to Phono adapter wired to pins 1, 4 & 2 of it's DIN plug should work, although the cassette recorder may have to be set to record mode. This would obviously mean that, with a working tape deck, recordings could be made from an external source (as designed), so internal modifications would be needed to create a true 'aux-in' facility.

27th Jun 2018, 8:09 am	#9
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,859	Re: Hitachi SDT 7785 Music Centre DIN to Phono Jonny, I see you have the user instructions. Is there anything in there that's pertinent to this? Nick

27th Jun 2018, 9:19 am	#10
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,335	Re: Hitachi SDT 7785 Music Centre DIN to Phono One can understand why in these mid-1970s Music Centres, AUX inputs were sometimes ommited. There were no CD player inputs to consider in those days and R2R was definitely on the wane as cassette technology was reaching its peak. __________________ Edward.

27th Jun 2018, 11:32 am	#11
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Hitachi SDT 7785 Music Centre DIN to Phono When I had a Sharp SG500E, which only had the standard 5-pin DIN socket, I was able to play external sources (CD Player & second tape deck) through the DIN socket. To make switching sources easy, I made up a switch box, using a 4-way push-button assembly, then plugged in the external audio devices. The box connected to the 500E via a 5-pin DIN plug, and good quality sound was available from the CD Player, etc. I no longer have any service info. for the 500E, but, IIRC, the DIN socket was wired to the usual convention.

27th Jun 2018, 2:52 pm	#12
Dai Corner Hexode Join Date: Oct 2016 Location: Newport, South Wales, UK. Posts: 278	Re: Hitachi SDT 7785 Music Centre DIN to Phono Just a hunch, but try depressing the Record button with a source connected to the DIN socket.

29th Jun 2018, 12:51 am	#13
John123 Heptode Join Date: Jan 2007 Location: Luton, Bedfordshire, UK. Posts: 891	Re: Hitachi SDT 7785 Music Centre DIN to Phono Looks like it's a 'Power Assisted' tape deck, so the bad news is it might not be possible to engage 'record and play' if the belts have perished. The good news is, as mentioned above, it might be possible to simply depress the 'record' button for monitoring. You may have to insert a cassette for it to do anything at all, so just make sure it's one where the write protect tabs have been removed beforehand (i.e. a blank cassette). If still no joy don't force any of the buttons as it may cause damage to the mechanism. You will have to have the belts replaced to get anything more from it. If, however, you can get the tape deck into record mode, you should be able to feed a signal into the mic socket. Just make sure the record level is turned up, and not peaking too far into the red on the VU's. __________________ Regards, John

29th Jun 2018, 1:56 am	#14
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Hitachi SDT 7785 Music Centre DIN to Phono Not nitpicking John, surely you mean make sure tab is present.

29th Jun 2018, 10:04 am	#16
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Hitachi SDT 7785 Music Centre DIN to Phono IIRC, when Ihad to SG500E, I didn't have to put the cassette deck into record mode to listen to external devices, but Hitachi may have wired their DIN socket differently to Sharp.

9th Aug 2018, 11:29 am	#18
jonnyburstow Retired Dormant Member Join Date: Jun 2018 Location: Reigate, Surrey, UK. Posts: 2	Re: Hitachi SDT 7785 Music Centre DIN to Phono Hello everyone, firstly let me apologise for not returning your messages sooner. I will now spend some time going through your advice and will try to answer as many questions as possible and give these tips a try. I have just tried a DIN to 3.5 jack and nothing has happened but I will try with a tape in and also with the record button on and off. I'll report back with my findings. Once again, thanks so much for taking your time to help me. Jonny

9th Aug 2018, 12:56 pm	#19
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,335	Re: Hitachi SDT 7785 Music Centre DIN to Phono So welcome back. Is it a 5 pin DIN? __________________ Edward.

9th Aug 2018, 3:42 pm	#20
cooperman Pentode Join Date: Feb 2018 Location: Cheshire, UK. Posts: 121	Re: Hitachi SDT 7785 Music Centre DIN to Phono Just a note about Phono to DIN adaptors. I purchased such an item recently and I found that it was wired for a MIDI interface rather than the way DIN plugs were wired for audio systems back in the 70s. Needless to say it did not work properly - I had to snip the plug and rewire.