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Old 21st Mar 2018, 11:15 pm   #1
Vakito227
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Default First TV Project - Ekco TCG316 - Any Advice Appreciated

Hi everyone, after restoring around half a dozen record players and two radios I thought I might step it up one and have a go at a television. I bought an Ekco TCG316 Tele-Gram and have already serviced the turntable and removed the chassis. Once I find someone to test the tube and it's not a dud I plan on replacing all the major capacitors, out of tolerance resistors, cleaning the pots, standard practice.

However although I'm more or less clued up on the dangers of CRTs, the EHT anode as well as the need for a standards converter, it's still quite unfamiliar territory for me so any guidance will be greatly appreciated.

There's a few things I'd like to know:

Firstly, the clip on the back of the neck which I'm guessing is the ion trap, I can't find any way to remove it - not that I want to at the moment. All the other ones I have seen have some sort of screw that clamps it together but this one I have no idea.

Secondly, according to the service data, the tube used is a Mazda CRM172 although the only sticker on the tube is a Pitrie sticker. The only information I have found on Pitrie is that they were a tube rebuilding service based in London so my tube must have been rebuilt sometime in its life. Anyway back to the CRM172, I did a bit or research and found that the Mazda CRM171 was a disaster of a tube which failed regularly, is the CRM172 just the same or is it like a revised and improved version of its predecessor?

Thirdly, are there any visual signs of a bad tube before I get it tested?

The man I bought it off said he got it when he moved into his house in '92 and the TV and radio did not work then but the record player did and he used it until that stopped working too, looking in the back I noticed the two 1.5A fuses have both been blown. Not sure what could have caused it to happen
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Old 21st Mar 2018, 11:40 pm   #2
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

The Ekco is an excellent choice for your TV restoration. I remember Pitrie tubes well, the company made very good rebuilt CRTs. Back in the sixties I bought my Pitrie tubes from a firm called "Tyne Television Tubes Ltd. Leazes, Newcastle.
You'll find plenty topics about similar Ekco TVs, look for related models T311, T327 and T330.

DFWB.
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Old 22nd Mar 2018, 12:26 am   #3
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Hi,
I have one of these sets bought many years ago for £1 from RWB!! I was unaware at that time of the issues with Mazda tubes and went ahead with the repair anyway.
I was rewarded with an excellent picture but must confess to never having finished it off or even looking at the record player
John (Heatercathodeshort) is a mine of fascinating information about Mazda CRT's & valves and their serious failings back in the 1950's. I had often wondered why Ekco chassis from this period use metal rectifiers when others were still using valves. It would seem that Mazda rectifiers were so bad that even the doubtful technology of metal rectifiers was a better option! Being tied to using Mazda, I guess they could not use other manufacturers valves & tubes.

My personal experience of restoring old TV's from the '50's & '60's is that CRT's cause few problems: LOPT's, however create many more headaches!
If the tube has lost vacuum rapidly it's pretty obvious. The screen phosphor tends to fall off leaving dark patches on the tube face.
Lots of tubes, when not used for 50 years, seem to show no emission when connected to a tester. They sometimes recover once they are back in use for a few hours. CRT testers also have the ability to restore/ rejuvinate emission with certain caveats.
By using a fairly mild 'cleaning' process on the tester, I usually find the emission recovers perfectly well and then stays OK.
Considering the use restored TV's will get, any shortening of life is not that relevant!
When most of these TV's were taken out of service, they probably worked OK and that was why they were kept. So it's a reasonable bet that the tube would have been OK as well.

By doing fairly minimal work on your chassis, it will be possible to get it to the point of producing some sort of picture so you can assess the tube. You can then decide how to progress from there.
By all accounts, the LOPT's in these chassis are very reliable. That said, dampness deep in the windings seems to be a frequent problem when they haven't been used for years.
Warming the EHT overwind by passing a controlled current through it for a week has proved to be very successful for many people. This is probably best done before first power up which is what I now do as a matter of course.

Be aware that the metalwork of the chassis is connected directly to one side of the mains. You must ensure that this is the NEUTRAL. That's probably the most important safety consideration apart from remembering that the HT smoothing caps can, under certain circumstances, stay charged for a time after switch off. The same applies to the CRT. If EHT has been applied to it and no picture produced, it will stay charged up to 16KV for a long time. It will bite you if you touch the EHT cap connection!!

Enjoy the restoration and good luck with it. I guess you will have to take the plunge and buy a standards converter now !!

All the best
Nick
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Old 22nd Mar 2018, 12:53 am   #4
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Quote:
Originally Posted by 1100 man View Post
I guess you will have to take the plunge and buy a standards converter now !!
Another option is a homebuilt modulator and a PC graphics card, for about 1/10th of the price, like mine.

https://youtu.be/ahzdx4KgWBg
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Old 22nd Mar 2018, 1:07 am   #5
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Many apologies, Graham, I forgot your excellent conversion method!! Out of interest, how easily obtainable is a suitable graphics card? I must say, that would make a very interesting project in itself: maybe I'll have to give it a go myself!
Cheers
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Old 22nd Mar 2018, 9:22 am   #6
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Quote:
Originally Posted by Vakito227 View Post
looking in the back I noticed the two 1.5A fuses have both been blown. Not sure what could have caused it to happen
There could be quite a few components that will blow the fuses, the prime candidate is the mains filter capacitor C124 on the Ekco sheet, also C125 connected to the chassis of the record deck.
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Old 22nd Mar 2018, 9:55 am   #7
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

I posted yesterday a reply but it is not here. CRT, check if white deposit in the neck was all I said, if so gone to air.

Not that I think yours had,
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Old 22nd Mar 2018, 6:35 pm   #8
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Thanks everyone for the advice, is there anyone or anywhere you would recommend to get my tube tested or should I commence chassis restoration on the likely assumption that the tube is okay?
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Old 22nd Mar 2018, 6:56 pm   #9
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Just restore as far as you need to go to get a raster, again as I said yesterday but it was deleted I think in fairness as you were asking for a "restoration".

Main caps ie boost cap coupling (frame line osc etc) Smoothing caps if bulging. If look OK you might wake them up gently with a variac or lamp limiter.

Pretty sure the CRT will be fine.
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Old 23rd Mar 2018, 1:01 am   #10
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Hi,
I would certainly start the restoration anyway without worrying too much about the tube. After all, if you got it tested and it showed zero emission (as several of mine have done), what would you do? You might conclude that it would not be worth continuing which would be a shame. Someone in a current thread said they reckoned that it took 8-10 hours of use to get the emission back up. As I said before, I've had very good results rejuvinating low emission tubes which is another option. If for some reason, such as open circuit heater, the tube was non recoverable, it is quite likely that someone can provide a spare or a different type can be substituted. So there are lots of possibilities!!
This should be a great candidate for a first restoration and should be an enjoyable project.
It would be great to see some pictures too!
All the best
Nick
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Old 23rd Mar 2018, 8:16 am   #11
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

I agree about not testing the tube. I have found some commercial testers read low on mono tubes. the emission being much better than indicated.
I have cringed in the past when I have read threads where the tube has been boosted before a picture had been displayed. (I hasten to add this was on the other now closed forum not on here!)
I nearly fell into the same trap myself years ago. I tested the tube on a KB VC2 that I was buying from a friend with his B and K. It showed almost no emission, but later when the set was working the picture was pretty good certainly not worth the risk of giving it a boost.
I suspected the tester was telling lies at the time so I tested a really good mono tube that was in a working set, it tested just above the red section.
I mentioned this (on the other forum) at the time and others agreed that they had found the same especially with the B and K.
I would see what the picture is like before thinking about "bopping"

Rich.
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Old 23rd Mar 2018, 9:08 am   #12
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

The Mazda CRM172 is one of Mazda's better tubes and is capable of giving an excellent picture. The LOPT windings themselves are 100% reliable but the 'plastic' case breaks down and arcs over.

Have a good look at the top where the EHT rectifier is mounted and check it for possible staining and break up.

No problem if it is failing. Construct a simple 'case' from Paxolin, Perspex or sheet plastic.

Other than that overhaul is very straightforward and always leads to a satisfactory result. The FM radio also performs very well.

As David has suggested, search the threads for 300 series EKCO. T310, T311, T326,T327, T330,T331 etc. They all employ a similar chassis with the same stock faults.

Any difficulties, just shout.

Mazda produced excellent valves but some were a bit odd. They had considerable difficulty producing rectifiers. The U801 is the classic nasty but they had even more problems with the boost diodes U281, U282, U301 and U191. [flaking cathodes] Even the 2v U25 wire ended EHT rectifier [not an equivalent to the 6.3v EY51] usually ended it's days in a ostentatious display of sparks and purple light. The later U26 BA based was 'better' but not as reliable as the Mullard EY86.
Later versions of the U191 were fault free.

The metal rectifier employed by Ekco was an AUTOMAT. I have never replaced one even when the chassis was subjected to horrendous storage conditions. Without doubt the best metal rectifier ever produced. They must start failing some day!

Please do not clean and scrub the chassis. Just a 1/2" paint brush and the vacuum cleaner is all that is required. Get it up and working first or you will generate enough man made faults to fill three pages. Good luck with it.
John.
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Old 23rd Mar 2018, 9:31 am   #13
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Quote:
I agree about not testing the tube. I have found some commercial testers read low on mono tubes. the emission being much better than indicated.
This is true, while CRT testers give an idea of emission, take it with a pinch of salt!

As your tube is a regun, I reckon it should be OK. I have restored three sets fitted with regunned CRT's, all produce very good pictures

I restored a very sad looking Bush TV32 a while back, the CRT heaters were disconnected from the heater chain indicating that there was a heater transformer fitted at some stage, possibly to boost the heaters or for getting round a heater cathode short.
Although there was no transformer in the set, first impressions were not good.

Despite this unpromising start, the tube told a different story....
The thread may give you a bit more confidence in your set. https://www.vintage-radio.net/forum/...d.php?t=124007

Mark
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Old 23rd Mar 2018, 11:08 am   #14
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Link to the restoration of the electrically similar Ferranti T1004:

https://www.vintage-radio.net/forum/...ht=Ekco+TCG316

DFWB.
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Old 23rd Mar 2018, 11:42 am   #15
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

From the 1957/58 Radio and Television servicing book.

Showing the modifications to the Ekco T310 chassis.

DFWB.
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Old 23rd Mar 2018, 7:10 pm   #16
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Thanks everyone again for all the advice, I'm taking notes

Quote:
Originally Posted by Heatercathodeshort View Post
Please do not clean and scrub the chassis. Just a 1/2" paint brush and the vacuum cleaner is all that is required.
I'll be honest, as soon as I brought it home I gave the innards a quick blast with compressed air to remove most of the trapped dust, I didn't have it set to a high pressure at all and the air line has a good in-line dryer so hopefully all should be well.
Quote:
Originally Posted by Heatercathodeshort View Post
Have a good look at the top where the EHT rectifier is mounted and check it for possible staining and break up.
The plastic casing looks more or less perfect to me, less can be said about the U26 valve I'll have to get another.

Main capacitors ordered as well as components to make a modulator, should be here in a few days.

Thanks
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Old 23rd Mar 2018, 9:06 pm   #17
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

The LOPTX could have been replaced at one time, it looks good from those photos.
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Old 24th Mar 2018, 10:25 am   #18
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

It certainly looks to be in good shape, it seems to be that some of these crumble and arc out, while others seem to clean up like new.

I use WD40 on a rag to clean the perspex, paying particular attention to the area round the EHT rectifier.
I reckon it will be fine, I have three sets using these LOPT's, all work without issue.

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Old 24th Mar 2018, 11:43 am   #19
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

I'm gathering the components to make a 405 modulator based on the early television museum's design. I'm not too experienced with inductors and can't figure out which one to buy based on the information on the diagram. The website I buy components from has options such as the inductance, Q minimum and test frequency. Bit confused
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Last edited by Vakito227; 24th Mar 2018 at 11:48 am. Reason: Corrections
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Old 24th Mar 2018, 4:31 pm   #20
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Default Re: First TV Project - Ekco TCG316 - Any Advice Appreciated

Search Ebay for "Inductor Shell Skeleton"
They are a former with a ferrite slug. Wind them with approx 20 SWG enamelled wire, close spaced.

Expect it to "just work", mine did, although a frequency counter or communications receiver can be very useful as can a GDO, or modern equivalent.

I like that Early Television Foundation circuit even though MC1374 chips are a bit more expensive than the MC1496 used in other designs that need a separate osc.
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