UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Television and Video

Notices

Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

Reply
 
Thread Tools
Old 8th Mar 2018, 4:04 pm   #1
Garrettimus
Diode
 
Join Date: Mar 2018
Location: São Paulo, Brazil
Posts: 3
Default SCART problem with Ferguson TV set

Dear friends, this is my very first post! I'm Marcus from Brazil...

I have a Ferguson TV set, it works perfectly with my classic BBC computers (via a especially installed DIN socket which was professionally done at stores back in the day), but, whenever I try the SCART socket, no matter what source, I get a reddish "background", although the other colours seem OK. This happens only with SCART. It's not the SCART cable though, I tried several to the same result.

The attached files show the normal picture (Beeb) versus the reddish ones (ZX Spectrum). Any ideas?

Also, there's a VIDEO button on the front, other than RGB, but there's actually no video socket on the back...

Please, help!
Attached Thumbnails
Click image for larger version

Name:	Normal.jpg
Views:	165
Size:	68.3 KB
ID:	158860   Click image for larger version

Name:	Speccy1.jpg
Views:	154
Size:	73.4 KB
ID:	158861   Click image for larger version

Name:	Speccy2.jpg
Views:	141
Size:	70.9 KB
ID:	158862  
Garrettimus is offline   Reply With Quote
Old 8th Mar 2018, 5:16 pm   #2
dj_fivos_sak
Heptode
 
Join Date: Mar 2015
Location: Lefkada, Greece
Posts: 618
Default Re: SCART problem with Ferguson TV set

I suspect broken or dry solder joints on the SCART connector. These were prone to breaking and that's why I'm not a big fan of SCART. If you wiggle the cable, does the picture restore to normal?
dj_fivos_sak is offline   Reply With Quote
Old 8th Mar 2018, 5:50 pm   #3
Garrettimus
Diode
 
Join Date: Mar 2018
Location: São Paulo, Brazil
Posts: 3
Default Re: SCART problem with Ferguson TV set

Quote:
Originally Posted by dj_fivos_sak View Post
I suspect broken or dry solder joints on the SCART connector. These were prone to breaking and that's why I'm not a big fan of SCART. If you wiggle the cable, does the picture restore to normal?
Thanks for your reply, I did that but it didn't work.
Garrettimus is offline   Reply With Quote
Old 8th Mar 2018, 8:17 pm   #4
Dave Moll
Dekatron
 
Dave Moll's Avatar
 
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 3,577
Default Re: SCART problem with Ferguson TV set

In that case it's probably going to be a matter of opening up the TV to check the state of the wiring to the socket.
__________________
Mending is better than Ending (cf Brave New World by Aldous Huxley)
Dave Moll is offline   Reply With Quote
Old 8th Mar 2018, 8:41 pm   #5
Garrettimus
Diode
 
Join Date: Mar 2018
Location: São Paulo, Brazil
Posts: 3
Default Re: SCART problem with Ferguson TV set

Quote:
Originally Posted by Dave Moll View Post
In that case it's probably going to be a matter of opening up the TV to check the state of the wiring to the socket.
Thank you very much, Dave. I'll have a friend do that for me, I'm not into Electronics.
Garrettimus is offline   Reply With Quote
Old 11th Mar 2018, 12:35 am   #6
Stuart R
Hexode
 
Stuart R's Avatar
 
Join Date: May 2011
Location: Letchworth Garden City, Hertfordshire, UK.
Posts: 328
Default Re: SCART problem with Ferguson TV set

Hello Marcus,

I don't remember these sets, but would the DIN socket be expecting TTL level, 0-5V RGB signals? I think that's what these home computers sent out.

Are you saying this set has both DIN and SCART connectors?

A SCART socket is expecting much smaller 0-700mV RGB signals, so maybe the old computers are over-driving things. If only the Spectrum had this red tint, I'd suggest a small fault in the Red channel on the Spectrum was appearing as a big red signal to the more sensitive SCART input stages. However, you say the Red tint is on all SCART pictures, which would suggest a minor TV fault, sadly.

If you still get 'snow' on the screen if you select the video channel, then maybe that button is just designed to give a more stable picture from a VCR wired with an RF lead into the aerial socket.

If the screen goes black when you select the video channel, maybe the set is expecting composite video on SCART pin 20. This would be on the yellow socket if you've bought a SCART to phono/RCA/Cinch adapter.

Other people here may have worked on these sets back in the day and have a better idea than me.

Good luck.
Stuart R is offline   Reply With Quote
Old 11th Mar 2018, 3:54 am   #7
julie_m
Dekatron
 
Join Date: May 2008
Location: Derby, UK.
Posts: 6,601
Default Re: SCART problem with Ferguson TV set

Some TV manufacturers cheaped out on the SCART connectors, and relied only on the soldered connections to the motherboard to support the socket, instead of riveting it to the board and/or screwing it to the outer case of the set. It did not help that, by dint of the form of the set not making it easy to turn around, one was often having to work by feel just to insert or remove the SCART plug.

In the event of loss of sound in one speaker, or weird colour problems such as complete loss of blue, the advice was always the same: Re-solder all the pins of the SCART connector. Moving the plug in the socket will not always restore the broken connection. Once I overcame my phobia of TV sets, I fixed a few with this simple method.

The SCART connector is designed to be able to accept a full composite colour video signal with blanking and sync (CVBS), or it can accept an RGB signal and use the CVBS input only for timing. If the earth return for the red signal has become disconnected, that could cause your problem. The BBC Micro's RGB output is suitable for connecting to a SCART input with just a few resistors and two diodes; a TV repairer could fit a suitable DIN socket, but it and the SCART socket should not both be connected at the same time -- permanent damage is very unlikely, but weird visual effects are practically certain!
__________________
Julie {formerly known AJS_Derby}
julie_m is offline   Reply With Quote
Old 11th Mar 2018, 10:17 am   #8
mark2collection
Pentode
 
mark2collection's Avatar
 
Join Date: Jul 2010
Location: Royal Berkshire, UK.
Posts: 130
Default Re: SCART problem with Ferguson TV set

I'm not familiar with that TV, but have seen something similar on an early scart Sony portable.

This would work fine on scart RGB, but scart composite (same socket) would produce a very colorful picture from 'some' satellite receivers.

Adding a 75 ohm resistor from pin 20 to ground cured the problem for the Sony, but for other TV's, adding 75 ohms in series with pin 20 cured identical issues.

Take all the usual precautions if you open up the TV, optionally, add 75 ohms in the lead if there's space.

From memory, my old workshop had a scart connector with a toggle switch & resistors to 'select' series/parallel or off, for the 75 ohm resistor. Crickey, that was a while back!

I still have a Sony portable from the early 90's, cracking picture on Freesat HD! (RGB).

Mark
mark2collection is offline   Reply With Quote
Old 11th Mar 2018, 12:58 pm   #9
Maarten
Octode
 
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 1,751
Default Re: SCART problem with Ferguson TV set

Since every colour has its own ground return, I'd start by checking these for loose connections. Red uses pin 13.
Maarten is offline   Reply With Quote
Old 11th Mar 2018, 2:05 pm   #10
yesnaby
Octode
 
yesnaby's Avatar
 
Join Date: Jul 2005
Location: Newport, Gwent, UK.
Posts: 1,416
Default Re: SCART problem with Ferguson TV set

Nice looking TV and cabinet!
yesnaby is offline   Reply With Quote
Old 14th Mar 2018, 11:57 pm   #11
McMurdo
Dekatron
 
McMurdo's Avatar
 
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 3,038
Default Re: SCART problem with Ferguson TV set

Its a TX85 isn't it? The scart was a seperate board fitted through a knock-out on the back panel?

The BBC gives out, in addition to UHF, RGB TTL I think, I'm sure that's what the corresponding Microvitec Cub would've been on a DIN socket. The standard Sinclair Spectrum only has UHF but had an unofficial mod for composite video which ought to be scart compatible. TTL normally requires divider resistors hidden inside the scart lead but the guy who fitted the din input to the Ferg would've scaled it appropriately.
__________________
Kevin
McMurdo is offline   Reply With Quote
Old 15th Mar 2018, 9:16 am   #12
Dave Moll
Dekatron
 
Dave Moll's Avatar
 
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 3,577
Default Re: SCART problem with Ferguson TV set

The BBC Micro does indeed output at TTL levels. To cope with this I made up a lead with series resistors to attenuate the signals down to the 1V P-P required by the SCART on the TV/monitor I used with it. I don't remember off-hand what value I used, and would need to open up the plug to check if the information is needed.
__________________
Mending is better than Ending (cf Brave New World by Aldous Huxley)
Dave Moll is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 1:00 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Copyright ©2002 - 2018, Paul Stenning.