GEC 2121 colour tv from 1974 - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Tazman1966 · 18th Jan 2008, 1:06 am

I think that it was some of the touch tuned models C2113H

Heatercathodeshort · 18th Jan 2008, 10:43 am

I used to love this series of GEC sets, in fact all GEC sets! Its odd how some engineers have a real struggle with certain models and others don't. Its all about knowing the stock faults and to eliminate most of them when the set is on the bench. Piles of troubles could be eliminated by replacing a handful of cheap componenets in most receivers reducing the service call rate to more than 2 or 3 years in most cases.
As Steve mentions the neon lamps age and darken causing their strike voltage to increase. This caused channel hopping and certain neons sticking on resulting in frustrating channel change. All the neons must be changed to guarantee a 'matched set' as near as possible. Once the power supply is set up correctly the set should run reliably. I used to sell large numbers of these sets reconditioned and can honestly say I did not have the slightest problems with any of them. I certainly would have remembered if I had done! Good luck with it Marcus! Happy Days. Regards, John.

marcus 3500 · 19th Jan 2008, 9:09 pm

Hi all

Thank you FERNSEH for the transistor info

and Steve P for the Charles Hyde info

and Mike Phelan, Studio263, Dr. Dave, Welsh Anorak, mickash, Tas and John for all the info cheers guys

Hi Lee the GEC killed my 2AMP variac, the set is using 720MA connected directly to the mains after the degauss finishes.

Parts fitted so far to get a full picture, TR455, C452, C455, C457, C458,C462still more work is needed and i hope to have it all done this week. Thanks again guys for all the help

Regards

Marcus.........

System A · 19th Jan 2008, 11:07 pm

Hi Marcus , well done, the tube looks good , my friend"s parents rented one of these from Rumbellows for years . Years ago i had a 20" model which was the same style but instead of the touch button unit it had a six button varicap unit .
Regards . Gary.

Tazman1966 · 20th Jan 2008, 7:01 pm

Looking good Marcus

. A nice save as there can't be too many of these left now.

Quote:

Originally Posted by System A

...20" model which was the same style but instead of the touch button unit it had a six button varicap unit...

Hello Gary. I seem to remember there was a 6 push button kit to retro fit to these models due to the not very reliable touch tune selectors due mostly to worn out neons and sometimes the the chip as well. I'm sure it was described in "Television" magazine some time.

System A · 20th Jan 2008, 7:06 pm

Hi Taz you are right about the kit , but the set i had must have had the button unit fitted from new because there were no presets on the back cover , not even any holes where they might have been . The set also had the cardboard back cover similar to the hybrid model with the big round crt bulb cover .
Regards . Gary .

marcus 3500 · 20th Jan 2008, 11:18 pm

Thanks Gary and Tas

Today the set died

with the rear of the set facing me i switched it on and R710 decided to start smoking and preset HT control now reads 400ohm should be 1K, and R709 should be 270K but reads 650ohm then reads 100K if you move the leads it will read 265K then the reading just jumps around so i guess it's all R709s fault.

Im going to change all the resistors later on this week but could a kind member tell me if it would be ok to change C705 to a 10UF cap, at the moment it's a 6.8UF but i don't have any, it's part of the soft start section of the PSU and is not in the R&T 73/74 book so i've included a picture from TV mag cheers.

Marcus.........

Steve_P · 20th Jan 2008, 11:49 pm

Should be OK. Check those transistors too - and that zener on the Line Panel mentioned earlier!

Cheers,

Steve P

Hunts smoothing bomb · 20th Jan 2008, 11:54 pm

Hi Marcus,
That's a shame to hear about your set, still though it is only sounding like a resistor, let's hope that is all it is. before it went smokey smokey though it looks like you had a decent picture on it. The colours look nice and strong. Well done mate, Usually I only like valve sets but this set (from it's front) looks like it should have valves if you know what I mean. keep us all posted on your progress!

Cheers
Lee

Dr-Watts · 21st Jan 2008, 6:19 pm

I told you it'd be a cracking set !

The one I did for my shop had a few ... ahem ... teething problems

But in the end it was excellent, in fact I used it as a bench set until I closed the doors for the last time in 2001.

Keep at it Markus !

Dr. Dave

marcus 3500 · 10th Feb 2008, 11:04 pm

Hi all

The Resistors i needed to finish this set off arrived on friday, i've not been on here since 25th of January working away etc and i've just finished an old Dynatron music centre. Now thats out of the way i hope to finish the GEC this week fingers crossed.

Hi Lee i guess it does kinda look like a hybrid set all the caps and ic's are dated 1973 so the set maybe from late 1973 ? i 've got a 2040 GEC thats hybrid and some of the boards in that set are dated 1973.

Hi Dave cheers

Regards

Marcus..........

Chris55000 · 11th Feb 2008, 1:54 pm

Hi!

Colour scans of PCB layout drawings, parts lists, chunks of cct. diagram (subject to forum rules!) now available from me on request if needed! Good luck with the restoration!

Chris Williams

Top Cap · 11th Feb 2008, 10:30 pm

Just a quick note about the 47V zener that often goes dead short. This is meant to happen in the event that the 40V rail goes to high and is in fact called a crowbar zener. Due to a difference in supply volts at the factory in Wales, we always recommended dealers to re-adjust the SET HT volts control when the sets were taken from their cartons. We used to also recommend that dealers in the first instance set the HT control for 40V on that rail rather than the 186V. If the 40V was set correct it certainly gave less chance of early failures. BTW, I recommended the fitting of a bleed resistor on later models as otherwise the main HT blocks packed quite a wallop! I found that out when I was on a TLO visit to Midlands Electricity Board (MEB), who sold quite a few of our sets. I also discovered many odd faults to reception, especially the colour decoder were directly caused by interference from the mains cable that was routed close to the boards. Simply re-routing the mains around the opposite side of the chassis often cured the strangest of faults. Les

marcus 3500 · 11th Feb 2008, 11:42 pm

Hi all

Thanks Chris and Top Cap for the info

Hi Steve

The blue tilt control P501 value is what i need to know, is it the same type Green Tilt control 500 Ohms cheers mate

The PSU is finished but i've decided to remove the chassis to replace a few caps and clean the EHT lead and trippler etc, im working tomorrow so will be finishing the set off on Saturday.

Regards

Marcus.........

marcus 3500 · 11th Feb 2008, 11:47 pm

Forgot to say the set is dated 20 June 1973.

Regards

Marcus.......

Steve_P · 11th Feb 2008, 11:51 pm

Blue Tilt P501 - 250 Ohms. With a resistor in series with it, which I think (eyes letting me down) is R502 - 90 Ohms.

My eyesight's getting bad....

Cheers,

Steve P.

marcus 3500 · 11th Feb 2008, 11:55 pm

Cheers Steve for the super quick info

Regards

Marcus......

Hybrid tellies · 12th Feb 2008, 1:16 am

Nice one. These were not to bad sets and use to have regular stock faults. They did lend themselves nicely for servicing. From what I can remember the most common failing on these were the neons fitted to the channel change. We were forever changing them to clear faults such as stuck on one channel or switching back to BBC1 on it's own.

Top Cap · 14th Feb 2008, 1:37 am

While you have the PSU on the bench, check out R701 - 180k. These had a tendency to go high value, causing gradual then total loss of brightness

Les

marcus 3500 · 14th Feb 2008, 10:05 pm

Cheers Simon

Cheers Les

Regards

Marcus..........

18th Jan 2008, 1:06 am	#21
Tazman1966 Nonode Join Date: May 2006 Location: St Albans, Herts, UK. Posts: 2,193	Re: GEC 2121 colour tv from 1974 I think that it was some of the touch tuned models C2113H __________________ All the very best, Tas

18th Jan 2008, 10:43 am	#22
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: GEC 2121 colour tv from 1974 I used to love this series of GEC sets, in fact all GEC sets! Its odd how some engineers have a real struggle with certain models and others don't. Its all about knowing the stock faults and to eliminate most of them when the set is on the bench. Piles of troubles could be eliminated by replacing a handful of cheap componenets in most receivers reducing the service call rate to more than 2 or 3 years in most cases. As Steve mentions the neon lamps age and darken causing their strike voltage to increase. This caused channel hopping and certain neons sticking on resulting in frustrating channel change. All the neons must be changed to guarantee a 'matched set' as near as possible. Once the power supply is set up correctly the set should run reliably. I used to sell large numbers of these sets reconditioned and can honestly say I did not have the slightest problems with any of them. I certainly would have remembered if I had done! Good luck with it Marcus! Happy Days. Regards, John.

19th Jan 2008, 9:09 pm	#23
marcus 3500 Retired Dormant Member Join Date: May 2006 Location: South Yorkshire, UK. Posts: 351	Re: GEC 2121 colour tv from 1974 Hi all Thank you FERNSEH for the transistor info and Steve P for the Charles Hyde info and Mike Phelan, Studio263, Dr. Dave, Welsh Anorak, mickash, Tas and John for all the info cheers guys Hi Lee the GEC killed my 2AMP variac, the set is using 720MA connected directly to the mains after the degauss finishes. Parts fitted so far to get a full picture, TR455, C452, C455, C457, C458,C462still more work is needed and i hope to have it all done this week. Thanks again guys for all the help Regards Marcus......... Attached Thumbnails

19th Jan 2008, 11:07 pm	#24
System A Pentode Join Date: Feb 2006 Location: County Durham, UK. Posts: 234	Re: GEC 2121 colour tv from 1974 Hi Marcus , well done, the tube looks good , my friend"s parents rented one of these from Rumbellows for years . Years ago i had a 20" model which was the same style but instead of the touch button unit it had a six button varicap unit . Regards . Gary.

20th Jan 2008, 7:06 pm	#26
System A Pentode Join Date: Feb 2006 Location: County Durham, UK. Posts: 234	Re: GEC 2121 colour tv from 1974 Hi Taz you are right about the kit , but the set i had must have had the button unit fitted from new because there were no presets on the back cover , not even any holes where they might have been . The set also had the cardboard back cover similar to the hybrid model with the big round crt bulb cover . Regards . Gary .

20th Jan 2008, 11:18 pm	#27
marcus 3500 Retired Dormant Member Join Date: May 2006 Location: South Yorkshire, UK. Posts: 351	Re: GEC 2121 colour tv from 1974 Thanks Gary and Tas Today the set died with the rear of the set facing me i switched it on and R710 decided to start smoking and preset HT control now reads 400ohm should be 1K, and R709 should be 270K but reads 650ohm then reads 100K if you move the leads it will read 265K then the reading just jumps around so i guess it's all R709s fault. Im going to change all the resistors later on this week but could a kind member tell me if it would be ok to change C705 to a 10UF cap, at the moment it's a 6.8UF but i don't have any, it's part of the soft start section of the PSU and is not in the R&T 73/74 book so i've included a picture from TV mag cheers. Marcus......... Attached Thumbnails

20th Jan 2008, 11:49 pm	#28
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: GEC 2121 colour tv from 1974 Should be OK. Check those transistors too - and that zener on the Line Panel mentioned earlier! 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 Jan 2008, 11:54 pm	#29
Hunts smoothing bomb Octode Join Date: Oct 2005 Location: Wimborne, Dorset, UK. Posts: 1,407	Re: GEC 2121 colour tv from 1974 Hi Marcus, That's a shame to hear about your set, still though it is only sounding like a resistor, let's hope that is all it is. before it went smokey smokey though it looks like you had a decent picture on it. The colours look nice and strong. Well done mate, Usually I only like valve sets but this set (from it's front) looks like it should have valves if you know what I mean. keep us all posted on your progress! Cheers Lee __________________ Lee

21st Jan 2008, 6:19 pm	#30
Dr-Watts Heptode Join Date: Dec 2006 Location: Milton Keynes, Buckinghamshire, UK. Posts: 696	Re: GEC 2121 colour tv from 1974 I told you it'd be a cracking set ! The one I did for my shop had a few ... ahem ... teething problems But in the end it was excellent, in fact I used it as a bench set until I closed the doors for the last time in 2001. Keep at it Markus ! Dr. Dave __________________ Do you have the scope to be a TV repair man

10th Feb 2008, 11:04 pm	#31
marcus 3500 Retired Dormant Member Join Date: May 2006 Location: South Yorkshire, UK. Posts: 351	Re: GEC 2121 colour tv from 1974 Hi all The Resistors i needed to finish this set off arrived on friday, i've not been on here since 25th of January working away etc and i've just finished an old Dynatron music centre. Now thats out of the way i hope to finish the GEC this week fingers crossed. Hi Lee i guess it does kinda look like a hybrid set all the caps and ic's are dated 1973 so the set maybe from late 1973 ? i 've got a 2040 GEC thats hybrid and some of the boards in that set are dated 1973. Hi Dave cheers Regards Marcus..........

11th Feb 2008, 1:54 pm	#32
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,874	Re: GEC 2121 colour tv from 1974 Hi! Colour scans of PCB layout drawings, parts lists, chunks of cct. diagram (subject to forum rules!) now available from me on request if needed! Good luck with the restoration! Chris Williams

11th Feb 2008, 10:30 pm	#33
Top Cap Octode Join Date: Mar 2006 Location: Watford, Hertfordshire, UK. Posts: 1,270	Re: GEC 2121 colour tv from 1974 Just a quick note about the 47V zener that often goes dead short. This is meant to happen in the event that the 40V rail goes to high and is in fact called a crowbar zener. Due to a difference in supply volts at the factory in Wales, we always recommended dealers to re-adjust the SET HT volts control when the sets were taken from their cartons. We used to also recommend that dealers in the first instance set the HT control for 40V on that rail rather than the 186V. If the 40V was set correct it certainly gave less chance of early failures. BTW, I recommended the fitting of a bleed resistor on later models as otherwise the main HT blocks packed quite a wallop! I found that out when I was on a TLO visit to Midlands Electricity Board (MEB), who sold quite a few of our sets. I also discovered many odd faults to reception, especially the colour decoder were directly caused by interference from the mains cable that was routed close to the boards. Simply re-routing the mains around the opposite side of the chassis often cured the strangest of faults. Les __________________ Whether the Top Cap is Grid or Anode - touching it will give you a buzz either way!

11th Feb 2008, 11:42 pm	#34
marcus 3500 Retired Dormant Member Join Date: May 2006 Location: South Yorkshire, UK. Posts: 351	Re: GEC 2121 colour tv from 1974 Hi all Thanks Chris and Top Cap for the info Hi Steve The blue tilt control P501 value is what i need to know, is it the same type Green Tilt control 500 Ohms cheers mate The PSU is finished but i've decided to remove the chassis to replace a few caps and clean the EHT lead and trippler etc, im working tomorrow so will be finishing the set off on Saturday. Regards Marcus......... Attached Thumbnails

11th Feb 2008, 11:47 pm	#35
marcus 3500 Retired Dormant Member Join Date: May 2006 Location: South Yorkshire, UK. Posts: 351	Re: GEC 2121 colour tv from 1974 Forgot to say the set is dated 20 June 1973. Regards Marcus....... Attached Thumbnails

11th Feb 2008, 11:51 pm	#36
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: GEC 2121 colour tv from 1974 Blue Tilt P501 - 250 Ohms. With a resistor in series with it, which I think (eyes letting me down) is R502 - 90 Ohms. My eyesight's getting bad.... 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...?

11th Feb 2008, 11:55 pm	#37
marcus 3500 Retired Dormant Member Join Date: May 2006 Location: South Yorkshire, UK. Posts: 351	Re: GEC 2121 colour tv from 1974 Cheers Steve for the super quick info Regards Marcus......

12th Feb 2008, 1:16 am	#38
Hybrid tellies Nonode Join Date: Jan 2004 Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area. Posts: 2,967	Re: GEC 2121 colour tv from 1974 Nice one. These were not to bad sets and use to have regular stock faults. They did lend themselves nicely for servicing. From what I can remember the most common failing on these were the neons fitted to the channel change. We were forever changing them to clear faults such as stuck on one channel or switching back to BBC1 on it's own. __________________ Simon BVWS member

14th Feb 2008, 1:37 am	#39
Top Cap Octode Join Date: Mar 2006 Location: Watford, Hertfordshire, UK. Posts: 1,270	Re: GEC 2121 colour tv from 1974 While you have the PSU on the bench, check out R701 - 180k. These had a tendency to go high value, causing gradual then total loss of brightness Les __________________ Whether the Top Cap is Grid or Anode - touching it will give you a buzz either way!

14th Feb 2008, 10:05 pm	#40
marcus 3500 Retired Dormant Member Join Date: May 2006 Location: South Yorkshire, UK. Posts: 351	Re: GEC 2121 colour tv from 1974 Cheers Simon Cheers Les Regards Marcus..........