Decca Bradford - UK Vintage Radio Repair and Restoration Discussion Forum

mikee01 · 7th Oct 2020, 7:23 pm

Hi I have a Decca Bradford series 30 tv with no sound. The picture is fine and I'm using a DVD player through a RF modulator. I know the amp is fine as I've put a separate audio source through it from the out put of the IF panel. I'm not an expert and only understand the very very basics. Would I be right to assume the fault is in the IF panel?
I've checked for dry joints lose connections, just basic stuff. Does anyone have any ideas on what to check or where I maybe able to get another IF panel? Thanks for your time.

19Seventy7 · 8th Oct 2020, 6:34 am

Hi Mike

Am I right in assuming the separate audio source came from the speaker of the TV? Did you have to retune the TV to get the audio?

It could possibly be your signal source and the TV don't quite match, our system has the audio signal 6Mhz away from the video signal, whereas other continental sources are 5.5Mhz away from video.

If you reconnect the DVD player to the TV and tune slightly out of video, do you get audio and no video?

'77

Welsh Anorak · 8th Oct 2020, 9:48 am

Hi. No offence meant, of course, but please remember the chassis of the Bradford is connected to mains neutral and the usual precautions need to be observed.
If you get sound from the input of the amp as you say you've done, then, yes, the fault's in the IF panel. Firstly check the RF modulator's doing its job by using another TV - some are meant for European use and won't work on 6mHz. Alternatively feed in the signal from an old VCR. If this proves the fault's in the TV, then it's likely the intercarrier sound IC's faulty, though it could be an associated transistor of course. If you've got the chance of a replacement board that might save some time, but it's always nice to get the old one going again - it won't be a difficult fix. Hopefully.

Heatercathodeshort · 9th Oct 2020, 9:22 am

Just to add I have serviced countless Decca Bradfords and I can't remember a sound fault other than maybe a duff PCL82 and that was very rare.
As Glyn has suggested I would have a look at your signal source. John.

Hybrid tellies · 9th Oct 2020, 9:48 am

Like John I have serviced countless Decca Bradfords in my time. Most of the sound faults were around the PCL82 valve sound output stage.
I can't remember ever having to change out the intercarrier sound MC1351 chip.
Check your signal source on a know working set.

Simon

mikee01 · 9th Oct 2020, 12:50 pm

Thank you all for the feedback. I know the amplifier side of it works as I took the audio feed directly from the DVD player and fed it into the audio wire on the output of the IF panel. I have no way of checking the audio output from the RF modulator so maybe it is only sending a video signal. I guess I'll have to find another source VCR or an old video game. Thanks again

7th Oct 2020, 7:23 pm	#1
mikee01 Diode Join Date: Oct 2020 Location: Bristol, UK. Posts: 3	Decca Bradford Hi I have a Decca Bradford series 30 tv with no sound. The picture is fine and I'm using a DVD player through a RF modulator. I know the amp is fine as I've put a separate audio source through it from the out put of the IF panel. I'm not an expert and only understand the very very basics. Would I be right to assume the fault is in the IF panel? I've checked for dry joints lose connections, just basic stuff. Does anyone have any ideas on what to check or where I maybe able to get another IF panel? Thanks for your time.

8th Oct 2020, 6:34 am	#2
19Seventy7 Octode Join Date: Jun 2018 Location: Essex, UK. Posts: 1,307	Re: Decca Bradford Hi Mike Am I right in assuming the separate audio source came from the speaker of the TV? Did you have to retune the TV to get the audio? It could possibly be your signal source and the TV don't quite match, our system has the audio signal 6Mhz away from the video signal, whereas other continental sources are 5.5Mhz away from video. If you reconnect the DVD player to the TV and tune slightly out of video, do you get audio and no video? '77

8th Oct 2020, 9:48 am	#3
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,921	Re: Decca Bradford Hi. No offence meant, of course, but please remember the chassis of the Bradford is connected to mains neutral and the usual precautions need to be observed. If you get sound from the input of the amp as you say you've done, then, yes, the fault's in the IF panel. Firstly check the RF modulator's doing its job by using another TV - some are meant for European use and won't work on 6mHz. Alternatively feed in the signal from an old VCR. If this proves the fault's in the TV, then it's likely the intercarrier sound IC's faulty, though it could be an associated transistor of course. If you've got the chance of a replacement board that might save some time, but it's always nice to get the old one going again - it won't be a difficult fix. Hopefully. __________________ Glyn www.gdelectronics.wales

9th Oct 2020, 9:22 am	#4
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Decca Bradford Just to add I have serviced countless Decca Bradfords and I can't remember a sound fault other than maybe a duff PCL82 and that was very rare. As Glyn has suggested I would have a look at your signal source. John.

9th Oct 2020, 9:48 am	#5
Hybrid tellies Nonode Join Date: Jan 2004 Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area. Posts: 2,965	Re: Decca Bradford Like John I have serviced countless Decca Bradfords in my time. Most of the sound faults were around the PCL82 valve sound output stage. I can't remember ever having to change out the intercarrier sound MC1351 chip. Check your signal source on a know working set. Simon __________________ Simon BVWS member

9th Oct 2020, 12:50 pm	#6
mikee01 Diode Join Date: Oct 2020 Location: Bristol, UK. Posts: 3	Re: Decca Bradford Thank you all for the feedback. I know the amplifier side of it works as I took the audio feed directly from the DVD player and fed it into the audio wire on the output of the IF panel. I have no way of checking the audio output from the RF modulator so maybe it is only sending a video signal. I guess I'll have to find another source VCR or an old video game. Thanks again