Ekco T161 Lack of height - UK Vintage Radio Repair and Restoration Discussion Forum

DoctorWho · 1st Apr 2006, 12:41 pm

I've been working on an Ekco T161 and have a problem in that the set has very reduced height, around 1" in fact.

The set has had all of the condensers changed, except for the main electrolytic (C65/C66 trader sheet 1039). The U25 has also been replacedas has C38 in the EHT line.

The height control itself does work and varies the height of the raster, it's just very narrow. Width is fine and all other picture controls appear to be working as they should.

If anyone has any suggestions with this height problem I'd be very grateful, I'm not sure if I should be ordring a replacement (V8) 20P1, (V16) 6L18 or should be looking elsewhere?

Any advice appreciated.

Thank you.

Peter.

Aerodyne · 1st Apr 2006, 5:03 pm

I feel sure others will be able to assist more accurately, but I was wondering if, assuming all voltages are correct, there might be a problem with the field output transformer or the field scan coils. I see there's a 470 ohm (R72, Trader) resistor across the coils. Possible low value? A scope would help with this fault. Of course you might be right about the valve changing, but even with a low emission bottle I'd not have expected such a severe limiting of scan, more likely a reduced scan with non-linearity when pushed 'open'.
Sorry I can't be of more help: I think the last time I saw one of these I was 13 years old...
-Tony

Danny · 1st Apr 2006, 9:50 pm

Hi peter the hold is locked so i would say its in the output stage and will be a resistor gone high so have a few cold checks on the resistors around the output valve and hight control befor suspecting valve failer also check the supply to bothe the output stage and the osc anode load if the hight is even but low then i wouldnt think the scancoils are to blame check your new caps are all where thay should be we have all made boo boos and wasted time tracing a fault we have caused if we are brave enough to admit it

. check also the value of the hight control and lin as these can change with age as well as resistors. my money would be on the resistor vaues going high though.
Danny

DoctorWho · 1st Apr 2006, 10:11 pm

Thanks for the advice Danny, much appreciated. I'll get a test meter tomorrow and check the areas you have highlighted. The resistors are all originals so you may well be right there. The height is even, and does lock, it is adjusted by the height control, but obviously you can't open it very far. Thanks also for the tip about checking the condensers, it's all too easy to make a mistake and I'll certainly double check those.

I'll let you know what I find.

Peter.

Mike Phelan · 2nd Apr 2006, 8:00 am

Peter
IIRC, the height control is fed from the boost rail with a high value resistor - typically 1.2meg, to give a linear part of the RC ramp.

Check that this resistor has not gone high.

Heatercathodeshort · 2nd Apr 2006, 6:41 pm

Hello Peter,
Something tells me that the 6L18 will be ok. They are a very good valve and emission held up very well. If you have any old heater transformer, 6.3v type I would suggest as a test of the output stage/scan coils and output transformer, you connect one end of the winding to chassis and the other end via a .1uf capacitor to the grid of the 6L18. If the stage is working correctly a much improved, but distorted degree of scan should appear.
As you have checked all the capacitors and the resisitor from the H.T. line to the frame blocking oscillator transformer, it is 1Mohm on my circuit, I would suggest that the only component left if the transformer itself.
Under the fault condition, is the picture locked but just lacking height? Suggest you examine this point again. If its rolling all over the place unfortunately the transformer looks u's. Not surprising after 55 years. Regards John.

DoctorWho · 2nd Apr 2006, 9:44 pm

Hello John,

Thanks for your input. Unfortunately I suspect you may well be right here, it's true that I haven't tried replacing the 6L18, but I have checked and double checked the condensers and resistors, the 1 meg resistor was a little high (not much) but I replaced it anyway, and this made no difference. Thanks for the tip about the 6.3 volt transformer, I'll certainly try that, but I suspect that you're right about the transformer.

The picture does lock, but not very well, it's very difficult to get it to lock and remain stable, and of course it's such a tiny picture that it's also very hard to judge.

This, I'm afraid, is a problem. Does anyone have a suitable transformer going spare that they would be willing to sell to me please? If so please send me a PM.

Thanks again,

Peter.

DoctorWho · 5th Apr 2006, 5:44 pm

Well the fault turned out to be the most unusual. There were a few very low value condensers in this set which looked exactly like resistors, even down to the coloured bands. I've got quite a few radios and TV sets in my collection and I have never seen one of these type of condensers before, my oldest set (radio) is 1931, so I presume these did not have wide useage?

Anyway when I realised that they were in fact condensers and not resistors that made things much easier, they are now all changed and the set runs a treat!

Thanks again to everyone for the help with this set.

All the best,

Peter.

Ed_Dinning · 5th Apr 2006, 9:27 pm

Hi Peter, a few people have been caught with those. They were also fitted to 50's radios. They loked like a 10K resistor with rounded ends, but were about as reliable as the usual Hunts!

Ed

Heatercathodeshort · 6th Apr 2006, 7:45 pm

Hello again Peter,
I'm very pleased that you managed to get the Ekco T161 working at last. Those capacitors! Yes they were made by EIRE a company owned by EKCO. They made resistors, pots and capacitors. The coloured bands correspond with the resistor colour code but I expect they have faded over the years. The confussion may arise due to the last colour band being the tolerance but dont ask me what the colours were! You will also find in some Ekco sets an odd looking 'fat resistor' in the frame circuit. It is in fact a selenium diode used as an interlace filter.......
This is another case of having to study the circuit diagram and component location pictures to identify each component. I use a selection of highlighter pens to mark resistors, capacitors and diodes etc, eliminating each one as they are replaced one at a time..[Perhaps I should change my userword from Heatercathodeshort to Oneatatime..]
Regards John.

Heatercathodeshort · 7th Apr 2006, 7:47 am

Sorry Peter! The name of the company was not as I spelt it in the above reply, incorrectly, ERIE..!
The company owned by EKCO was EGEN, the name of which appears on most of the rotary controls on EKCO receivers. ERIE did of course make resistors as well as a wide range of components but was not owned by EKCO and was not responsible for the 'mini sausages'. Regards John.

Top Cap · 7th Apr 2006, 6:28 pm

As a very old (long retired from TV) engineer, the first bee-line for this fault was the resistor in series with the Height control, as mentioned earlier in this thread. A low frame valve usually manifested itself as additional bottom cramping of the picture. Thinking of those dodgey capacitors, I never forgave Hunts for what they did for the reputation of British set manufacturers but others made similar mistakes. If you ever have to service the old valve Grundig tape recorders you will find large square 'Black Toffee' capacitors made by Wima. They were just as bad and every one should be changed without thinking. As an aside, may I say I think this Forum is a fantastic place to visit, looking at some of the set collections on here reminds me of myself, at the then young age of 12, stripping down an old band 1 TV carcass to get hold of the large round Focus magnet. Oh! such happy times!

1st Apr 2006, 12:41 pm	#1
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Ekco T161 Lack of height I've been working on an Ekco T161 and have a problem in that the set has very reduced height, around 1" in fact. The set has had all of the condensers changed, except for the main electrolytic (C65/C66 trader sheet 1039). The U25 has also been replacedas has C38 in the EHT line. The height control itself does work and varies the height of the raster, it's just very narrow. Width is fine and all other picture controls appear to be working as they should. If anyone has any suggestions with this height problem I'd be very grateful, I'm not sure if I should be ordring a replacement (V8) 20P1, (V16) 6L18 or should be looking elsewhere? Any advice appreciated. Thank you. Peter.

1st Apr 2006, 5:03 pm	#2
Aerodyne Octode Join Date: Jun 2004 Location: Hampton Vale, Peterborough, UK. Posts: 1,698	Re: Ekco T161 Lack of height I feel sure others will be able to assist more accurately, but I was wondering if, assuming all voltages are correct, there might be a problem with the field output transformer or the field scan coils. I see there's a 470 ohm (R72, Trader) resistor across the coils. Possible low value? A scope would help with this fault. Of course you might be right about the valve changing, but even with a low emission bottle I'd not have expected such a severe limiting of scan, more likely a reduced scan with non-linearity when pushed 'open'. Sorry I can't be of more help: I think the last time I saw one of these I was 13 years old... -Tony

1st Apr 2006, 9:50 pm	#3
Danny Heptode Join Date: Jul 2003 Location: North Walsham, Norfolk, UK. Posts: 516	Re: Ekco T161 Lack of height Hi peter the hold is locked so i would say its in the output stage and will be a resistor gone high so have a few cold checks on the resistors around the output valve and hight control befor suspecting valve failer also check the supply to bothe the output stage and the osc anode load if the hight is even but low then i wouldnt think the scancoils are to blame check your new caps are all where thay should be we have all made boo boos and wasted time tracing a fault we have caused if we are brave enough to admit it . check also the value of the hight control and lin as these can change with age as well as resistors. my money would be on the resistor vaues going high though. Danny

1st Apr 2006, 10:11 pm	#4
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Ekco T161 Lack of height Thanks for the advice Danny, much appreciated. I'll get a test meter tomorrow and check the areas you have highlighted. The resistors are all originals so you may well be right there. The height is even, and does lock, it is adjusted by the height control, but obviously you can't open it very far. Thanks also for the tip about checking the condensers, it's all too easy to make a mistake and I'll certainly double check those. I'll let you know what I find. Peter.

2nd Apr 2006, 8:00 am	#5
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Re: Ekco T161 Lack of height Peter IIRC, the height control is fed from the boost rail with a high value resistor - typically 1.2meg, to give a linear part of the RC ramp. Check that this resistor has not gone high. __________________ Mike.

2nd Apr 2006, 6:41 pm	#6
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Ekco T161 Lack of height Hello Peter, Something tells me that the 6L18 will be ok. They are a very good valve and emission held up very well. If you have any old heater transformer, 6.3v type I would suggest as a test of the output stage/scan coils and output transformer, you connect one end of the winding to chassis and the other end via a .1uf capacitor to the grid of the 6L18. If the stage is working correctly a much improved, but distorted degree of scan should appear. As you have checked all the capacitors and the resisitor from the H.T. line to the frame blocking oscillator transformer, it is 1Mohm on my circuit, I would suggest that the only component left if the transformer itself. Under the fault condition, is the picture locked but just lacking height? Suggest you examine this point again. If its rolling all over the place unfortunately the transformer looks u's. Not surprising after 55 years. Regards John.

2nd Apr 2006, 9:44 pm	#7
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Ekco T161 Lack of height Hello John, Thanks for your input. Unfortunately I suspect you may well be right here, it's true that I haven't tried replacing the 6L18, but I have checked and double checked the condensers and resistors, the 1 meg resistor was a little high (not much) but I replaced it anyway, and this made no difference. Thanks for the tip about the 6.3 volt transformer, I'll certainly try that, but I suspect that you're right about the transformer. The picture does lock, but not very well, it's very difficult to get it to lock and remain stable, and of course it's such a tiny picture that it's also very hard to judge. This, I'm afraid, is a problem. Does anyone have a suitable transformer going spare that they would be willing to sell to me please? If so please send me a PM. Thanks again, Peter.

5th Apr 2006, 5:44 pm	#8
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Ekco T161 Lack of height Well the fault turned out to be the most unusual. There were a few very low value condensers in this set which looked exactly like resistors, even down to the coloured bands. I've got quite a few radios and TV sets in my collection and I have never seen one of these type of condensers before, my oldest set (radio) is 1931, so I presume these did not have wide useage? Anyway when I realised that they were in fact condensers and not resistors that made things much easier, they are now all changed and the set runs a treat! Thanks again to everyone for the help with this set. All the best, Peter. Attached Thumbnails

5th Apr 2006, 9:27 pm	#9
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Ekco T161 Lack of height Hi Peter, a few people have been caught with those. They were also fitted to 50's radios. They loked like a 10K resistor with rounded ends, but were about as reliable as the usual Hunts! Ed

6th Apr 2006, 7:45 pm	#10
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Ekco T161 Lack of height Hello again Peter, I'm very pleased that you managed to get the Ekco T161 working at last. Those capacitors! Yes they were made by EIRE a company owned by EKCO. They made resistors, pots and capacitors. The coloured bands correspond with the resistor colour code but I expect they have faded over the years. The confussion may arise due to the last colour band being the tolerance but dont ask me what the colours were! You will also find in some Ekco sets an odd looking 'fat resistor' in the frame circuit. It is in fact a selenium diode used as an interlace filter....... This is another case of having to study the circuit diagram and component location pictures to identify each component. I use a selection of highlighter pens to mark resistors, capacitors and diodes etc, eliminating each one as they are replaced one at a time..[Perhaps I should change my userword from Heatercathodeshort to Oneatatime..] Regards John.

7th Apr 2006, 7:47 am	#11
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Ekco T161 Lack of height Sorry Peter! The name of the company was not as I spelt it in the above reply, incorrectly, ERIE..! The company owned by EKCO was EGEN, the name of which appears on most of the rotary controls on EKCO receivers. ERIE did of course make resistors as well as a wide range of components but was not owned by EKCO and was not responsible for the 'mini sausages'. Regards John.

7th Apr 2006, 6:28 pm	#12
Top Cap Octode Join Date: Mar 2006 Location: Watford, Hertfordshire, UK. Posts: 1,270	Re: Ekco T161 Lack of height As a very old (long retired from TV) engineer, the first bee-line for this fault was the resistor in series with the Height control, as mentioned earlier in this thread. A low frame valve usually manifested itself as additional bottom cramping of the picture. Thinking of those dodgey capacitors, I never forgave Hunts for what they did for the reputation of British set manufacturers but others made similar mistakes. If you ever have to service the old valve Grundig tape recorders you will find large square 'Black Toffee' capacitors made by Wima. They were just as bad and every one should be changed without thinking. As an aside, may I say I think this Forum is a fantastic place to visit, looking at some of the set collections on here reminds me of myself, at the then young age of 12, stripping down an old band 1 TV carcass to get hold of the large round Focus magnet. Oh! such happy times!