UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV 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.

Closed Thread
 
Thread Tools
Old 5th Sep 2019, 12:31 pm   #1
Tazman1966
Nonode
 
Tazman1966's Avatar
 
Join Date: May 2006
Location: St Albans, Herts, UK.
Posts: 2,193
Default A bonus GEC 2028

This 19" dual standard colour set came as an added bonus during a swap of a Ferguson 3703 for an Ultra 6703 which I’d been after for ages. It must be the first time that a freebie has been of much more interest than the run of the mill swap!

Being the foolhardy fool that I sometimes can be, and after a cursory check which showed nothing untoward other than the fact that the PCBs were coated in an oily film, I plugged it in and switched it on. After a short time we had some action on the screen and with a twiddle of the tuner buttons, a picture. This was most impressive considering its fifteen year plus slumber. There was plenty to do though with very weak line sync and no frame sync, no B-Y, hissing focus control, poor frame linearity and low width. The set was then put on the back burner whist I turned my attention to the aforementioned Ultra, the write up of which has been documented elsewhere.

Fast forward many months and following a long recuperation from a hernia operation where the manhandling of televisions was completely out of the question for me, I was at last in a position to do something with this GEC. I invited Mike Bennett down to come and play too but plans were changed as he had car troubles so couldn’t visit but we both thought about fettling this set into good working order so with the help of my wife, I lumbered the GEC into my car and made the journey to the midlands and Mike’s house.
After a much needed cuppa, the set was hoisted onto Mike’s bench. Sure enough the faults previously displayed had not “fixed themselves” although the hissing focus control had stopped its hissy fit. Possibly damp before.
The previous repairer had done a lot of work on this set, perhaps in an effort to gain long term reliability with a blanket change of loads of electrolytic and some polyprop caps in the frame timebase and treated it to a set of new valves apart from the PCF80 for some reason.

Now what order to fix the faults? Let’s get the picture stable first so delve into the sync circuitry first. Clipping Mike’s ‘scope onto the input to the sync separator valve from TR9, the video clipper showed that the sync signal was all but missing. The signal on the base of the transistor was more as it should have been so the transistor was suspected but there was also a grotty looking electrolytic in the base. Sadly, in the tussle to change it (damn double sided print!) it got destroyed so I was unable to check it. A new one failed to improve matters though. It had to be the transistor, surely? An equivalent to the BC187 was grafted in (a BC213) and bingo! We now had a rock solid picture. A check on the transistor that was removed though showed that it was fine. Very strange. This wasn’t the end of the sync story however!

Next up was the lack of B-Y and drifting blue greyscale. Given the symptoms, I was convinced that fault lay in the clamp section of the PCL84 in the B-Y channel and with an air of confidence, pounced on the 8M2 anode resistor which proved to have risen to double its value. After replacing it with a smug smile on my face, we looked at the picture now and no bloddy change! A faulty PCL84 maybe? Nope! Voltage checks showed that the output and clamp stages were working correctly. I followed the wiring to the CRT base panel. And all was ok. There was a 680ohm series resistor but that also checked out ok. The 8M2 anode resistor that had gone high must have had an effect but there was nothing. Surely not the CRT? At this point we called it a day feeling happy and deflated in equal measure – well me at least!

Part 2 to follow…
Attached Thumbnails
Click image for larger version

Name:	IMG_20190901_161521.jpg
Views:	367
Size:	142.4 KB
ID:	189532   Click image for larger version

Name:	IMG_20190901_161557.jpg
Views:	354
Size:	120.0 KB
ID:	189533  
__________________
All the very best,
Tas
Tazman1966 is offline  
Old 5th Sep 2019, 7:36 pm   #2
ben
Dekatron
 
ben's Avatar
 
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 7,484
Default Re: A bonus GEC 2028

Interesting stuff, looking forward to the next instalment! That oily film looks 'orrible and may well be to blame for some of the faults I expect.
__________________
Regards,
Ben.
ben is offline  
Old 5th Sep 2019, 7:43 pm   #3
McMurdo
Dekatron
 
McMurdo's Avatar
 
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
Default Re: A bonus GEC 2028

I've had bad experiences with those old pluggable / auto insertion resistors, looking at your closeup. They always give me a sinking feeling
__________________
Kevin
McMurdo is offline  
Old 5th Sep 2019, 8:30 pm   #4
FERNSEH
Dekatron
 
FERNSEH's Avatar
 
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
Default Re: A bonus GEC 2028

Hi Taz,
Is your GEC 2028 still in it's original dual standard condition? It'll be recalled mine was converted to receive only 625 transmissions. I wish I hadn't done so but it was common practise in the seventies to disable the 405 line function.

DFWB.
FERNSEH is offline  
Old 6th Sep 2019, 12:54 am   #5
Tazman1966
Nonode
 
Tazman1966's Avatar
 
Join Date: May 2006
Location: St Albans, Herts, UK.
Posts: 2,193
Default Re: A bonus GEC 2028

Sunday dawned and I made a beeline for the workshop and examined further the path to the blue CRT grid and there it was. A dry joint like a volcano on the CRT base panel just by pin 12! Again, connection was required to both sides of the panel and with that done, I had controllable blue background and the return of the B-Y signal.

By now, Mike had risen from his slumber and I showed him the rather nice and colourful, if a little non linear, picture! The next step, linearity. With the top and main lin controls up at one end, the geometry was not far out at all but I reckon it could be improved upon.

The previous owner had replaced the usual suspects such as the cathode bypass components choosing a hefty wirewound as the cathode resistor. That wasn’t going to fail in a hurry! He’s also changed some of the capacitors in the linearity network with one exception, C525, a 1kV 0.01uF blue and white Dubilier in the linearity network. We pounced on it and sure enough, it was leaky. Even a small leak is critical in this position so with a new one soldered in, the linearity could be adjusted to my satisfaction.

Next , the width that was only just making it needed to be looked at. There are three tappings for this adjustment requiring a readjustment of the set EHT/Boost pot afterwards. The manual stated that the green lead from the tripler is to be adjusted on the tagstrip at the rear of the LOPT assembly. Unfortunately, the lead was not green although one of the leads on tag 5 was green and due to the positioning of the tripler, it was virtually impossible to see what leads were what! Eventually, using resistance checks, it was established that a black lead was the one that should’ve been green! With this set on the max width tap, the width was better but the EHT was low even with the set EHT/boost pot on max. A couple of high value resistors around the VDR had gone even higher, so with these replaced, we had ample width and correct EHT.

Our joy was short lived however as upon returning the chassis back to its normal position, and switching back on, we had the no sync problem again. Surely not another transistor? The voltages were not conclusive but the ‘scope display was the same as before. I suggested unhooking the feed to the sync separator, V3, a PCF80 and checking the trace now. It was back to normal. Something odd must’ve been happening inside the valve. Now a piece of equipment that I don’t have is a valve tester but Mike does so digging out the correct cards for a PCF80, we put it through its paces and very strangely, there was a major inter electrode leak between the screen grid and the control grid. This had been the only valve that the original repairer had not replaced so a new one went in and perfect lock again.

It has to be said that not much in the way of setting up was required with the convergence being particularly good. I managed to ****** up the purity by knocking the very loose purity rings. They were loose due to a snapped plastic retaining lug but with the blue lateral magnet pushed hard up against them after re-adjustment, they were secure.

The only thing left to do now is refinish the cabinet which is grotty with some nasty scratches, particularly on the top. I’ll probably end up sanding it right back and then staining it and finishing with a spray lacquer. Luckily, the front is in good condition. It won’t get house room until the cabinet is in proper order!

Ben – the oily stuff doesn’t seem to have caused any fault that I can see but I’m still none the wiser as to what it is!

Kevin – those resistors always seem to go high in equipment of this age.

David – As far as dual standard capability is concerned, it is all operational although the correct rod that goes from the tuner to the system switch was missing. Mike’s lent me the one from his 2030 for now as the makeshift one that was in this set was kind of bendy and caused not very reliable system switching.

Here are some pictures of the old girl in action. I’m pleased with how it turned out and will be even more pleased when I’ve sorted the cabinet!
Attached Thumbnails
Click image for larger version

Name:	IMG_20190901_201730.jpg
Views:	354
Size:	88.3 KB
ID:	189584   Click image for larger version

Name:	IMG_20190901_201746.jpg
Views:	337
Size:	87.2 KB
ID:	189585   Click image for larger version

Name:	IMG_20190901_202109.jpg
Views:	344
Size:	85.0 KB
ID:	189586   Click image for larger version

Name:	IMG_20190901_202441.jpg
Views:	316
Size:	77.9 KB
ID:	189587   Click image for larger version

Name:	IMG_20190901_202244.jpg
Views:	320
Size:	68.5 KB
ID:	189588  

__________________
All the very best,
Tas
Tazman1966 is offline  
Old 6th Sep 2019, 8:03 am   #6
ben
Dekatron
 
ben's Avatar
 
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 7,484
Default Re: A bonus GEC 2028

What a result! The tube looks especially good. And most importantly, a rare set made usable again - well done!
__________________
Regards,
Ben.
ben is offline  
Old 6th Sep 2019, 8:52 am   #7
mark pirate
Dekatron
 
mark pirate's Avatar
 
Join Date: Mar 2008
Location: Worthing, West Sussex, UK
Posts: 5,185
Default Re: A bonus GEC 2028

What an excellent set, I had the same model in my bedroom in the late 70's.
That too had a superb picture, I remember the red light on the front to indicate a colour programme.

For an early colour set the physical size was quite compact, although it was still a heavy beast!

Once you have refinished the cabinet, you should give it pride of place in your collection, these sets were capable of outstanding picture quality.

Although very good, the CVC5 that replaced my GEC, never matched the vibrant colours of the 2028.


Mark
mark pirate is offline  
Old 6th Sep 2019, 8:59 am   #8
McMurdo
Dekatron
 
McMurdo's Avatar
 
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
Default Re: A bonus GEC 2028

very pretty and looks nice and sharp!
__________________
Kevin
McMurdo is offline  
Old 6th Sep 2019, 9:02 am   #9
Hunts smoothing bomb
Octode
 
Hunts smoothing bomb's Avatar
 
Join Date: Oct 2005
Location: Wimborne, Dorset, UK.
Posts: 1,407
Default Re: A bonus GEC 2028

Very nice Taz!
The set looks to be in pretty good shape on the inside with a decent tube to boot!
The cabinet work shouldn't be too daunting and I agree that sanding it back and re-staining will be the way forward to get a good uniform finish.
I recommend the use of "Blackfriar" woodstain, available in many colours and a good product. You've got a goodun there mate, well done!
Makes me wish that I still had mine now.

Cheers
__________________
Lee
Hunts smoothing bomb is offline  
Old 6th Sep 2019, 11:27 am   #10
linescan87
Heptode
 
linescan87's Avatar
 
Join Date: Mar 2014
Location: Meath, Ireland
Posts: 547
Default Re: A bonus GEC 2028

Great write up Taz, well done on getting it going. Such a cracking crt to.
__________________
All the best, John Joe

www.youtube.com/c/ojnojirishvintagetvandradio
linescan87 is offline  
Old 6th Sep 2019, 12:07 pm   #11
dazzlevision
Dekatron
 
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 3,596
Default Re: A bonus GEC 2028

These are very nice sets and I always thought the colour rendition extremely good (I prefer the picture with CDA, compared to RGB CRT drive).

I've had my own GEC 2028 for 30+ years and I (like many) "single standardised" it, including removing the system switches and replacing them with wire links.

However, I did retain all the 405/625 switching components, so I shall restore it to full dual standard operation at some point.
dazzlevision is online now  
Old 6th Sep 2019, 12:40 pm   #12
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,884
Default Re: A bonus GEC 2028

Well done Taz (as usual) on a great set - and even the colour beacon works. I remember having one of these alongside a 19" Thorn 2000 and deciding this had the edge on the picture quality. CDA drive seemed to be a more sympathetic way of driving the tube.
That oily covering is odd, but I'm sure that's not the first time I've seen it in a GEC. Having said that, I've no idea what it is! However as it seems to be inert I'd leave well alone there.
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is offline  
Old 6th Sep 2019, 2:58 pm   #13
Hunts smoothing bomb
Octode
 
Hunts smoothing bomb's Avatar
 
Join Date: Oct 2005
Location: Wimborne, Dorset, UK.
Posts: 1,407
Default Re: A bonus GEC 2028

Quote:
Originally Posted by Welsh Anorak View Post
That oily covering is odd, but I'm sure that's not the first time I've seen it in a GEC. Having said that, I've no idea what it is! However as it seems to be inert I'd leave well alone there.
I had exactly the same oily covering all over the panels of the insides of a G6 that I had years ago and I was convinced that it was switch cleaner residue.

Cheers
__________________
Lee
Hunts smoothing bomb is offline  
Old 6th Sep 2019, 3:47 pm   #14
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,884
Default Re: A bonus GEC 2028

Possibly WD40? After all, if it frees rusty hinges it's bound to sort out a line sync problem on a TV....
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is offline  
Old 6th Sep 2019, 8:29 pm   #15
Graham G3ZVT
Dekatron
 
Graham G3ZVT's Avatar
 
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,676
Default Re: A bonus GEC 2028

Quote:
Originally Posted by Welsh Anorak View Post
Possibly WD40? After all, if it frees rusty hinges it's bound to sort out a line sync problem on a TV....
Lubricates the flywheel.
__________________
--
Graham.
G3ZVT
Graham G3ZVT is offline  
Old 7th Sep 2019, 6:15 pm   #16
davyrocket2
Pentode
 
Join Date: Apr 2011
Location: Westgate On Sea, Kent, UK.
Posts: 246
Default Re: A bonus GEC 2028

Stirling work Taz my eyesight is fairly good and in one of the photos I can see a Panasonic NV8610. I had a few of those myself, built to last but some did suffer with video heads wearing out due to the back tension being set too high.
davyrocket2 is offline  
Old 9th Sep 2019, 8:11 pm   #17
Tazman1966
Nonode
 
Tazman1966's Avatar
 
Join Date: May 2006
Location: St Albans, Herts, UK.
Posts: 2,193
Default Re: A bonus GEC 2028

Thanks for the comments folks!

Yesterday afternoon, I started to prepare the cabinet for refinishing. I gave it a thorough sanding down using three different grades of paper to achieve a nice smooth finish. Luckily the front is in good (although not perfect) condition. If it hadn't been so good, I would have had to have completely dismantled the set to properly strip the front. That said, I was nearly persuaded to by Mrs S who said that she would have preferred it in a lighter finish but the hassle of a complete strip down was too much for my increasingly lazy old ways!


After the rub down, I rubbed the bare wood over a couple of times with white spirit and allowed it to dry in the Sunday sunshine in readiness for the staining which will be the next time that I get some free time.


I put the set up on the bench and powered it up - the first time since I brought it back down from Mike's place. There is a fair amount of patterning on the screen. There appears to be some issue in the signals stages. Certainly someone has been in the UHF tuner before. In fact, the cover was off the side of it when I picked the set up. I am wondering though if the patterning is from my UHF modulators which are directly under the bench. This set does seem a bit "touchy" on the tuning so we'll see.


Thanks again
Attached Thumbnails
Click image for larger version

Name:	20190908_160011.jpg
Views:	172
Size:	97.2 KB
ID:	189842   Click image for larger version

Name:	20190908_160023.jpg
Views:	156
Size:	94.0 KB
ID:	189843   Click image for larger version

Name:	20190908_160710.jpg
Views:	162
Size:	94.0 KB
ID:	189844   Click image for larger version

Name:	20190908_161840.jpg
Views:	160
Size:	70.1 KB
ID:	189845  
__________________
All the very best,
Tas
Tazman1966 is offline  
Old 10th Sep 2019, 10:33 am   #18
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,884
Default Re: A bonus GEC 2028

I'm with Mrs Tas! Still, I'm sure its original finish is what you'd prefer, and I wouldn't relish stripping the set to get to the front panel. These sets always looked old before thir time - a bit like the Deccas - but now have a nice period look about them.
I think the rare Masteradio version had a light wood cabinet.
Hope no-one's been trying to "adjust" the tuner to get rid of the patterning.
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is offline  
Old 10th Sep 2019, 11:45 am   #19
Hunts smoothing bomb
Octode
 
Hunts smoothing bomb's Avatar
 
Join Date: Oct 2005
Location: Wimborne, Dorset, UK.
Posts: 1,407
Default Re: A bonus GEC 2028

Nice work Tas, cabinet veneer is looking pretty good.

You'll find that you won't need a stain as dark as yo think. On some cabinets that I have done I've found that just the application of the lacquer alone darkens the wood dramatically. Always best to try an inconspicuous area out first!

Cheers and good luck!
__________________
Lee
Hunts smoothing bomb is offline  
Old 10th Sep 2019, 1:40 pm   #20
beery
Heptode
 
beery's Avatar
 
Join Date: Jun 2006
Location: Ware, Hertfordshire, UK.
Posts: 988
Default Re: A bonus GEC 2028

Hi Tas,
It's going to be a great set when it is finished. Sometimes bonus sets are the best

Cheers
Andy
beery is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 2:45 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 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.