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 10th Jan 2017, 7:32 pm   #1
Mikey405
Octode
 
Mikey405's Avatar
 
Join Date: Jul 2006
Location: Solihull, West Midlands and Beaford, Devon
Posts: 1,626
Default Ekco TS46 Excitement

Hi everyone.

In the vein of Steve’s quickie write-up of his dual-standard GEC, I thought I’d just put a few words up about an Ekco TS46 that my pal Tone and I sorted out a few weeks back.

The set, actually an Ekco TS46/1 with the extra pre-amp stage, had been lying around in my spare room for a good few years after having been purchased from a chap somewhere near Salisbury (if my memory serves me right - which it rarely does). The cabinet was a bit wishy-washy with somebody having tried to re-varnish it in the past and a few small bits of veneer missing here and there but generally it wasn’t the worst I’d ever seen. The inside had obviously been used as a source of spares, having been raided of its speaker, its volume pot (more on this in a moment), the line-linearity pot and a few other sundry items including its original knobs, some wire-wound components and the back cover from the EHT cage. The volume pot was actually there – in a fashion – but it had actually been replaced with a random-value pot with no on-off switch (or connected wires) so that at least the set had a place to put all its knobs. (Murphy radio knobs as it turned out.) The sound stage had been modified somewhere along the way too – Not the official Ekco modification for distorted sound issues, which entailed disconnecting the feedback winding and making a few other circuit changes here and there, but some other unusual mod which Tone or I couldn’t really make head nor tail of. This was never going to be an A1 set (although it didn’t turn out that bad as it happened) so I thought a fairly quick restoration was called for. No Andy Beer amazing re-building and re-stuffing methods for me – My method was much more akin to a Friday-afternoon repair job with bright yellow Vishay custard caps and not much thought to originality underneath.

First of all the volume / on / off pot was replaced with something that looked suitable and wired up. The shaft was miles too long so that was cut down to size.

Next, the missing smoothing caps were replaced with some ancient-looking but suitable-value ones fished out of the loft. Unfortunately however, most of the caps (including the ones we’d just installed) were beyond reforming so I cut them open near the base with a hacksaw, Tone soldered in some new ones and we taped them back up again. Not a particularly glamorous re-stuffing process but when they were clamped back in the chassis they looked pretty good.

Next we set about re-wiring the audio stage to the original circuit diagram. The negative-feedback winding on the audio transformer seemed fine so it was put back to the pre-Ekco-mod circuit. The screened cables that fed the volume control were very crumbly so these were replaced with something modern but which looked reasonably similar.

Now our attention turned to the missing line-lin pot and some other wires which had inexplicably been cut off the height control. A new pot (not exactly the same value but near enough for me) was found in my big-bumper-box of old pots. It was installed and wired up – along with the wires which had been cut from the height control.

One of the two Visconols was missing from the RF EHT generator and the other one looked a little bit the worse for wear so these were also replaced. I know you can’t really tell what’s going on just from the look of the thing – but I just decided it might be nice to replace the manky looking one anyway. I had a pair of unused Visconols of the right value which I didn’t really expect to work all that well – but I soldered them in regardless.

Next the P61 EHT oscillator valve was tested on my finest Mullard-Never-Right valve tester and although I’m highly suspicious of the readings I get from my Mullard monster, the valve seemed to test okay with good emission. This particular P61 however was missing all its screening-paint so we decided to try out a bottle of “Graphit 33” paint that I had lying around. Tone masked up the base and I set to cleaning the remnants of old paint off the valve and then proceeded to spray it (out in the garden). Apart from a few “runs” it actually turned out remarkably well and so the valve was reinstalled back in the set.

The U22 EHT valve was next tested on the big Mullard tester and was shown to have absolutely zero emission. Now I just happened to have a pair of brand new U22 valves that our very own John Wakely had very kindly provided for another set, so one of those was borrowed and installed. As soon as I pressed the valve into its base however, one of the rivets holding it in gave way and the valve fell through the chassis. The rivets were drilled out, a suitable pair of nuts-and-bolts were quickly installed and all was well again. Whilst we were in the EHT section, I replaced the grotty-looking wax cap and a resistor on top of the transformer and then put the EHT cage back on, feeding the very crumbly rubber EHT cable through the hole in the can and connecting it up to the tube.

Now came the moment of truth. Everything wired up and ready to go, we just thought a final check to make sure the HT wasn’t too low resistance or anything might be in order. And it was a good job we did – In my haste to wire up the new smoothing capacitors, I’d managed to connect the earth wire that joins the mains transformer to one of the smoothing caps and the rest of the chassis directly to the output from the smoothing choke. This was quickly rectified and my obvious stupidity overlooked so that we could get to the interesting part. The set was plugged in and switched on.

We certainly had a good initial result. With my hand poised on the on / off switch, heaters started to glow. After about 20-30 seconds we actually had a line on the screen but, oddly, no line whistle. Or at least none that I could hear. The EHT was measured and it was showing 5.5KV, which is within five hundred volts of what it should be. (The manual says that it is supposed to be 6KV but I’m never sure exactly how they measure that as I never seem to get as much as they say when measured on my digital meter and Fluke HV probe.)

Adjusting the line-hold pot on the back of the set brought a just-about-audible whistle and improved the width of the line a bit. When measured, however, the lowest frequency I could get was about 15KHz. This turned out to be an incorrect-value resistor which had been soldered in at the top end of the line-hold pot. Installing the correct value (560 Ohms) restored correct line whistle and a much happier line stage.

To get some semblance of frame scan, it was the usual job of replacing the old wax-and-paper capacitors. The Ekco TS46 tag strips are really nice and easy to work on so the frame circuit caps were changed pretty quickly. This brought up a nice blank raster on which a vague test-cardy form could be made out but there wasn’t really much going on in the RF section.

A quick test of some of the 6F13s in the RF and video stages revealed that most of them were on their last legs (one of them only having seven pins!). The best of the dodgy 6F13s were used in the early RF stages and a small handful of new ones were extricated from the loft and installed.

After that we had a remarkably good picture – even the Mazda CRM92 has a fair bit of life in it. There was a little bit of height and width lacking and the frame linearity wasn’t all it could be. The lack of height was sorted with a nice new PEN45, the lack of width with a PEN46 and the frame linearity was sorted by soldering a 1K resistor in the cathode circuit of the frame valve as suggested in the manual. (Actually the manual suggests soldering in a variable resistor, but a fixed 1K was found to be fine.)

So there we are. A little bit of final fault-finding revealed a few out-of-tolerance resistors causing a bit of video crushing but other than that the set just needed minor adjustments to the shift twiddlers around the focus coil and it was as good as new. (Well, perhaps not quite as good as new, but not far off it.) The set was left running for nearly three hours, after which time the EHT had dropped by about 750V but it seemed perfectly stable at about 4.75KV and the picture was still fine. The new-old Visconols were, somewhat surprisingly, clearly perfectly okay so they were left in.

One thing I still need to do is to solder in some new EHT cable (some 20KV copper-core plain black spark plug cable has arrived and looks exactly the part). I’m in two minds as to whether to get the cabinet sorted – On balance I think I prefer it as it is with all its history, so I suspect I won’t get it tarted up. A couple of last things are that I still need an on / off / volume knob – rummaging in all manner of NVCF events has yet to reveal one (JW again very kindly managed to find me the three other knobs - Thanks John), and also the back of the EHT generator is missing. I know people used to remove them on purpose but I’d still like to find one. The back cover is also a little bit tatty but not too bad so unless another one turns up then I’ll happily keep the existing one.

Wow – That wasn’t so much of a quickie-write-up at all. Congratulations to anyone who has made it this far.

Thanks everyone.

Kind regards.

From Mike.

I scanned in the circuit from a "Trader" sheet so if anyone would like a copy, it can be found here:
http://www.oldtechnology.net/documents/Ekco_TS46.zip
Attached Thumbnails
Click image for larger version

Name:	WP_20170101_15_21_21_Pro.jpg
Views:	363
Size:	98.9 KB
ID:	135725   Click image for larger version

Name:	WP_20170101_16_19_08_Pro.jpg
Views:	347
Size:	83.2 KB
ID:	135726   Click image for larger version

Name:	WP_20170101_15_40_17_Pro.jpg
Views:	386
Size:	66.9 KB
ID:	135727   Click image for larger version

Name:	WP_20170102_14_04_47_Pro.jpg
Views:	389
Size:	91.1 KB
ID:	135728   Click image for larger version

Name:	WP_20170102_14_27_38_Pro.jpg
Views:	300
Size:	23.1 KB
ID:	135729  

__________________
G7TRF

Last edited by Mikey405; 10th Jan 2017 at 7:42 pm.
Mikey405 is offline  
Old 10th Jan 2017, 7:45 pm   #2
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Ekco TS46 Excitement

Nice job and a well laid out report.

I enjoy reading these TV success stories as it's an area I've never ventured into.
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 10th Jan 2017, 8:12 pm   #3
Colourstar
Octode
 
Colourstar's Avatar
 
Join Date: Feb 2006
Location: Ilkeston, Derbyshire, UK.
Posts: 1,397
Default Re: Ekco TS46 Excitement

Excellent stuff. Well done Mike and Tone! It's nice to see long-term residents of the to-do pile get some attention (that's the sets, not you two!)

Was this one conducted in your new bohemian working style (with berets and black polo necks) or was it within conventional working hours (with flat caps and brown overalls)?

Steve
Colourstar is offline  
Old 10th Jan 2017, 8:13 pm   #4
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
Default Re: Ekco TS46 Excitement

Ooooooh Mike. Well done! Any Ekcovision can be brought back to life, they really are incredible.
This one by your description was a very close candidate for the crusher but with your patience it has been brought back to working order.
I have a TS46 that I posted a rebuild of a good while back. The RF EHT unit really struggles. The coil needs to be 100% high Q and mine took many hours to stabilize due to the dreaded damp saturation.
The P61 power triode oscillator runs very hot inside that brass cage. If you remove the cage the EHT rises 1kv as it is very close to the coil and has a damping effect. I expect the cover was removed as the minimum possible.
RF EHT units produce a very high level of rich harmonics creating interference through the mains and by direct radiation but this is not so important now as it was 60 years ago.The RF system survived for around one year before flyback took over. The English Electric Company produced the best unit with SU2150A and 185BT generator but it must have cost a lot of money to manufacture.
I will have a knob hunt. I can use the example at the museum as a pattern. You never know! Regards, John.
Heatercathodeshort is online now  
Old 10th Jan 2017, 9:05 pm   #5
Freya
Octode
 
Freya's Avatar
 
Join Date: Jan 2009
Location: Falmouth, Cornwall, UK.
Posts: 1,987
Default Re: Ekco TS46 Excitement

What a great write up, another Ekco lives.

I really need to find one to complete my Ekco collection.
__________________
Stephen
_________"It`s only an old telly" ___
Freya is offline  
Old 10th Jan 2017, 9:13 pm   #6
McMurdo
Dekatron
 
McMurdo's Avatar
 
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
Default Re: Ekco TS46 Excitement

nice neat set. You made it sound easy!!
__________________
Kevin
McMurdo is offline  
Old 10th Jan 2017, 9:16 pm   #7
FERNSEH
Dekatron
 
FERNSEH's Avatar
 
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
Default Re: Ekco TS46 Excitement

I acquired my Ekco TS46 way back in 1982. It was in a dilapidated state and required major cabinet repairs. In those times the repairs were done with lots of filler, not a nice job really. In more recent times the cabinet has been rebuilt to the extent the only original part is the left side panel. Every else is new, the base, the right side panel, the cabinet top and the front panel.
Recently the mains transformer burnt out so a rewind will be required.
The set was bought from the Vintage Wireless Company, proprietor Tudor Rees.
The TS46 is a TRF receiver fix tuned for Alexandra Palace. In order the set could work in the West Country transmitter area some clever perso made a frequency shifter unit which employed a single 6A8GT a heptode radio frequency valve. The frequency changer unit was fitted inside the cabinet.
Introduced in 1947 the TS46 was the second post-war TV set to be made by Ekco. The first was the TSC30 which was essentially a pre-war design, an over engineered monster.

DFWB.
FERNSEH is online now  
Old 10th Jan 2017, 9:45 pm   #8
samjmann
Heptode
 
samjmann's Avatar
 
Join Date: Feb 2014
Location: Nottingham, UK.
Posts: 645
Default Re: Ekco TS46 Excitement

Loved reading this write-up, great to see another old chassis brought back to life. It was mentioned that the EHT generator on this unit was the 'RF type', rather than the flyback or early mains derived EHT. I've not heard of this type before, Can anyone direct me to some info on this topic please?

Regards, SJM
samjmann is offline  
Old 10th Jan 2017, 10:21 pm   #9
MonochromeMarc
Pentode
 
MonochromeMarc's Avatar
 
Join Date: Jan 2015
Location: Wakefield, West Yorkshire, UK.
Posts: 151
Default Re: Ekco TS46 Excitement

Hi Mikey,

Well you and Tone have done it again, what a lovely way to spend my evening with the company of your tales of do and dare, always wonderful and a smashing telly too.

Well done you two.

Marc.
MonochromeMarc is offline  
Old 10th Jan 2017, 11:18 pm   #10
Hunts smoothing bomb
Octode
 
Hunts smoothing bomb's Avatar
 
Join Date: Oct 2005
Location: Wimborne, Dorset, UK.
Posts: 1,407
Default Re: Ekco TS46 Excitement

Hi Mike,

Very nice write up mate, a credit indeed to you and Tone I enjoyed it right to the end!
A very good looking set, (must get myself a decent TV someday!)

You say the CRT has a fair bit of life left in it, by the definition displayed it looks truly excellent as the line structure is very clear, should be good for years.

It reminds me that I must get on with one of my sets...

Cheers
__________________
Lee
Hunts smoothing bomb is offline  
Old 11th Jan 2017, 12:08 pm   #11
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
Default Re: Ekco TS46 Excitement

Quote:
Originally Posted by samjmann View Post
I've not heard of this type before, Can anyone direct me to some info on this topic please?
The RF EHT unit was a completely separate screened unit usually containing a beam tetrode such as the 6V6G and a very high 'Q' coil assembly not unlike an early line output transformer. The Ekco TS46 employs a power triode P61.

A feedback winding on the coil together with the anode winding provide an oscillatory circuit. The high voltage secondary winding is wave wound in sections to reduce capacity, [damping] usually five or six as can be seen in Mike's picture.

The EHT rectifier such as the U22 [designed as a high voltage rectifier for mains EHT supplies] with a high current heater is supplied by a highly insulated winding on the mains transformer. This can be seen with the porcelain 'Screwit 'connectors just visible in another picture. Some versions use the familiar micro heater current EY51 or U37 with their heater powered from an additional winding on the coil itself.

The disadvantages are mainly the cost of the manufacture of a reliable unit.
The coil needs to be of the very best quality to maintain 'Q' wound with Litz wire.
The oscillator circuit produces rich harmonics that can create havoc with interference.
The circuit is power hungry and of poor efficiency.

It is said that Jules Thorn visited the design department at the Ferguson factory and complained that 'he was putting a ten shilling note in the back of each receiver'. This was the 842T series in 1948, the only Thorn receiver to employ RF EHT. They obviously had problems with it.

The circuit was taken from Television Receiver Servicing by Spreadbury. [1954]
Regards, John.
Attached Thumbnails
Click image for larger version

Name:	RF EHT.jpg
Views:	189
Size:	44.8 KB
ID:	135763  
Heatercathodeshort is online now  
Old 11th Jan 2017, 1:34 pm   #12
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
Default Re: Ekco TS46 Excitement

This is rather a nicely designed self contained EHT unit manufactured by 'HIVOLT Ltd. 34A Pottery lane, London S.W.11.
The valve employed is a Brimar 6BW6, the B9A based version of the 6V6GT with a similar circuit to the Ekco TS46.

The EHT output is dependent upon the H.T. available from the receiver chassis, typically 300/350v producing around 5/7kv.
The primary and grid coils can be seen at the bottom of the low loss Perspex former. The very small 1.2v two turn winding for the U37 filament are seen at the extreme base of the former.

No less than seven stacked windings for the EHT secondary. I have not powered this up but I bet the regulation is good.

How circumstances change. I expect that very small company thought they would be manufacturing these units for quite a few years not realizing that flyback was just around the corner. I wonder how long they lasted?

When I was a kid living in Wimbledon, many small industrial workshops existed. I was fascinated by the goings on along Beulah Road and to the rear of Merton High Street with the barn doors of small workshops open revealing men beavering away in small foundries, sparks flying and arc welding. All gone forever. Regards, John.
Attached Thumbnails
Click image for larger version

Name:	RF EHT unit (1).jpg
Views:	212
Size:	85.6 KB
ID:	135774   Click image for larger version

Name:	RF EHT unit (2).jpg
Views:	234
Size:	101.8 KB
ID:	135775  
Heatercathodeshort is online now  
Old 11th Jan 2017, 6:08 pm   #13
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
Default Re: Ekco TS46 Excitement

Just to conclude the data on RF EHT unit similar to the unit producing EHT for the TS46, I could not resist powering this up to see what it was capable of.

I replaced two decoupling .05uf waxies [note the oscillator frequency adjust trimmer] and connected it to my variable HT power supply.
It worked immediately. With 250v H.T. it developed a steady 5kv and with the H.T. increased to 350v the reading on the EHT meter rose to 7.5kv as per spec.

The RF radiation can be seen by this Neon screwdriver lighting brightly 9" from the top of the coil... [Lovely, and they thought CFLs were bad]

The effect of the radiating oscillator can be seen on the screen of this GEC BT1156 that happened to be on the bench at the same time.

Just a bit of fun for the sci fi fans..

Oh, the address of the makers should have been W11 not SW11. Regards, John
Attached Thumbnails
Click image for larger version

Name:	RF unit operating (2).jpg
Views:	217
Size:	90.9 KB
ID:	135780   Click image for larger version

Name:	RF unit operating (3).jpg
Views:	230
Size:	93.4 KB
ID:	135781   Click image for larger version

Name:	RF unit operating (5).jpg
Views:	234
Size:	95.0 KB
ID:	135782   Click image for larger version

Name:	RF unit operating (1).jpg
Views:	235
Size:	79.9 KB
ID:	135783   Click image for larger version

Name:	RF unit operating (4).jpg
Views:	271
Size:	70.6 KB
ID:	135784  

Heatercathodeshort is online now  
Old 11th Jan 2017, 6:42 pm   #14
bobhowe
Heptode
 
bobhowe's Avatar
 
Join Date: Jun 2005
Location: Sunderland, Tyne and Wear, UK.
Posts: 661
Default Re: Ekco TS46 Excitement

Hi John been forty years since I seen a ht power supply like yours they were been thrown out at the school I was at I should have I got one regards Bob
bobhowe is offline  
Old 11th Jan 2017, 8:44 pm   #15
Jac
Heptode
 
Jac's Avatar
 
Join Date: Jun 2006
Location: Eindhoven, Netherlands.
Posts: 640
Default Re: Ekco TS46 Excitement

Thank you Mike for this write-up.

I've always had a soft spot for the TS46.
(Not in my collection unfortunately.)

The last time I came across an RF EHT is when I restored my Pilot TV37.

Jac
Attached Thumbnails
Click image for larger version

Name:	2013-03-24 TV37 10 in.jpg
Views:	181
Size:	39.3 KB
ID:	135788  
Jac is offline  
Old 11th Jan 2017, 8:49 pm   #16
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
Default Re: Ekco TS46 Excitement

Mike's Ekco TS46 is one of the few chassis that employed this R.F. EHT system. I have mentioned the Ferguson 842T and the only others that come to mind are the English Electric, A rare 21" HMV 1820 and the RGD. Due to it's cost and poor regulation, it was shunned by most of the other popular manufacturers. You can't blame them.
This TS46 is a great example and a round of applause is needed for Mike and Tone for bringing it back to life! John.
Heatercathodeshort is online now  
Old 11th Jan 2017, 9:03 pm   #17
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
Default Re: Ekco TS46 Excitement

Superb write up and result.My TS46 is still sat here also it,s big brother the mirror lid job.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S
HamishBoxer is offline  
Old 12th Jan 2017, 10:14 pm   #18
FERNSEH
Dekatron
 
FERNSEH's Avatar
 
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
Default Re: Ekco TS46 Excitement

From the December 1957 Practical Television magazine, an advertisement for another RF EHT unit.
This one is called the NERA EHT unit and was marketed by a firm called P.A.M Ltd which I believe had no connection which the Pye Group firm.
The valve looks like a Mazda 6P25.
Because the EHT produced by the NERA is over 8KV this unit would be an unsuitable replacement for the RF system used in the Ekco TS46.

DFWB.
Attached Thumbnails
Click image for larger version

Name:	RF-EHT - Copy.jpg
Views:	146
Size:	63.2 KB
ID:	135825  

Last edited by FERNSEH; 12th Jan 2017 at 10:27 pm.
FERNSEH is online now  
Old 12th Jan 2017, 10:53 pm   #19
samjmann
Heptode
 
samjmann's Avatar
 
Join Date: Feb 2014
Location: Nottingham, UK.
Posts: 645
Default Re: Ekco TS46 Excitement

Thank you Heatercathodeshort for the description of the RF EHT generator. Well written and pictures as well! You learn something new in this business everyday on both old and new technologies.
My very first Tv repair was to solder a U25 EHT rectifier into a 60's Ekco under the careful tutelage of my Dad (a trolley-bus engineer). How things have changed.

Regards, SJM.
samjmann is offline  
Old 13th Jan 2017, 11:29 am   #20
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
Default Re: Ekco TS46 Excitement

They certainly have! Thanks, John.
Heatercathodeshort is online now  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 12:00 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 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.