Thorn/Marconiphone/Ferguson Tape Recorder - UK Vintage Radio Repair and Restoration Discussion Forum

JohnBHanson · 19th Oct 2011, 9:31 am

I have a two speed four track 5.75 inch reel version of this, but it does not record. I have looked at the DVD service sheets and it does not have the circuit diagram in it. It is the version with the amp/superimpose button and pause solenoid on it. Does anyone have the circuit diagram they can email me. Many thanks.

julie_m · 19th Oct 2011, 12:16 pm

When you say "it does not record", what exactly happens when you try? Does it leave the old signal behind? Does it leave the tape blank? Does it leave any recognisable trace of the "new" signal at all?

Most 1960s two-head recorders are very similar electronically; with a line-up of ECC83, ECL86, EM84 and semiconductor rectifier. (Sometimes a DM70 is used instead for the recording level indicator.) Nearly every connection in the machine goes through the record/play switch, so it's absolutely vital that this is clean. Your recorder has a "superimpose" function, which disables the erase head, so you need to clean that switch too.

This stuff is probably as good as anything else.

Steve_P · 19th Oct 2011, 1:45 pm

There should be a type or model no. on it. Let us know then we're all singing from the same hymn sheet. A photograph or two would be even better.

If it plays, then most, but not all, of the electronics are OK. The advice given above holds true. Are you using a microphone - these are the most common causes of problems like this if you erase OK but not record.

You're probably using the deck diagram rather the electronic diagram.

Cheers,

Steve P.

eric8650 · 20th Oct 2011, 7:17 pm

If there is no signal showing on the EM84 showing that there is no signal getting into the recorder. Check the microphone socket. It has a peculiar switch on it. If the contacts on this switch are o/c then recordings from the rear input sockets will be absent. Without knowing more thats the best advice I can give.

JohnBHanson · 21st Oct 2011, 2:37 pm

Thanks I have buzzed through the switches and they appear to be ok. Next attempt will be to scope the erase head signal, and see what that is like.

julie_m · 21st Oct 2011, 4:46 pm

You should have said before that you had an oscilloscope

It will make the fixing much easier, anyway, as you can follow a signal through all the way through from the input to the recording head -- or wherever it disappears, at any rate .....

You should see a nice large AC voltage at a few tens of kHz on the erase head, if the bias / erase oscillator is running properly. Use a 10:1 probe; not for the sake of the signal, but for the sake of the oscilloscope input! You should see the same frequency at the record/playback head.

ben · 22nd Oct 2011, 4:40 pm

I think first, you need to carry out the basic checks mentioned in posts 2 and 3, could save you some time....

19th Oct 2011, 9:31 am	#1
JohnBHanson Heptode Join Date: Aug 2009 Location: Worthing, Sussex, UK. Posts: 662	Thorn/Marconiphone/Ferguson Tape Recorder I have a two speed four track 5.75 inch reel version of this, but it does not record. I have looked at the DVD service sheets and it does not have the circuit diagram in it. It is the version with the amp/superimpose button and pause solenoid on it. Does anyone have the circuit diagram they can email me. Many thanks.

19th Oct 2011, 12:16 pm	#2
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Thorn/Marconiphone/Ferguson Tape Recorder When you say "it does not record", what exactly happens when you try? Does it leave the old signal behind? Does it leave the tape blank? Does it leave any recognisable trace of the "new" signal at all? Most 1960s two-head recorders are very similar electronically; with a line-up of ECC83, ECL86, EM84 and semiconductor rectifier. (Sometimes a DM70 is used instead for the recording level indicator.) Nearly every connection in the machine goes through the record/play switch, so it's absolutely vital that this is clean. Your recorder has a "superimpose" function, which disables the erase head, so you need to clean that switch too. This stuff is probably as good as anything else. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

19th Oct 2011, 1:45 pm	#3
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Thorn/Marconiphone/Ferguson Tape Recorder There should be a type or model no. on it. Let us know then we're all singing from the same hymn sheet. A photograph or two would be even better. If it plays, then most, but not all, of the electronics are OK. The advice given above holds true. Are you using a microphone - these are the most common causes of problems like this if you erase OK but not record. You're probably using the deck diagram rather the electronic diagram. Cheers, Steve P. __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

20th Oct 2011, 7:17 pm	#4
eric8650 Pentode Join Date: Sep 2011 Location: Skegness, Lincolnshire, UK. Posts: 103	Re: Thorn/Marconiphone/Ferguson Tape Recorder If there is no signal showing on the EM84 showing that there is no signal getting into the recorder. Check the microphone socket. It has a peculiar switch on it. If the contacts on this switch are o/c then recordings from the rear input sockets will be absent. Without knowing more thats the best advice I can give.

21st Oct 2011, 2:37 pm	#5
JohnBHanson Heptode Join Date: Aug 2009 Location: Worthing, Sussex, UK. Posts: 662	Re: Thorn/Marconiphone/Ferguson Tape Recorder Thanks I have buzzed through the switches and they appear to be ok. Next attempt will be to scope the erase head signal, and see what that is like.

21st Oct 2011, 4:46 pm	#6
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Thorn/Marconiphone/Ferguson Tape Recorder You should have said before that you had an oscilloscope It will make the fixing much easier, anyway, as you can follow a signal through all the way through from the input to the recording head -- or wherever it disappears, at any rate ..... You should see a nice large AC voltage at a few tens of kHz on the erase head, if the bias / erase oscillator is running properly. Use a 10:1 probe; not for the sake of the signal, but for the sake of the oscilloscope input! You should see the same frequency at the record/playback head. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

22nd Oct 2011, 4:40 pm	#7
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Thorn/Marconiphone/Ferguson Tape Recorder I think first, you need to carry out the basic checks mentioned in posts 2 and 3, could save you some time.... __________________ Regards, Ben.