Hi.
Iv'e been the lucky owner of an Ekco TSC30A for a couple of years. I was very lucky indeed to be given the set by David Boynes which I am eternally grateful for such a nice gift. Due to some health issues I haven't done as much as i would have like to have done, most of the work has been in dribs and drabs. David reconstructed the cabinet many years ago as it had been chopped up to make a table model. For a 9 inch screen it is a big set and heavy into the bargain. David had done some work on the set but it had been left for a while then when looked at again had some issues with focus and picture shift. It was felt at the time the focus coil was the issue then residual magnetism. Without a doubt the CRM92 is low emission and my personal opinion is the CRT is the main issue with poor edge focus. I do have the offer of another CRT but these days I am not keen on long runs, I'm hoping to get something organised soon though. In the meantime I'm going to fit a 7BP7 radar tube that I used with success on my 240 line experiments on an old scrap Bush TV22 chassis. Fitting it in the Ekco should be easy enough, the 2v heater can be connected in series with the 4v heaters foe the rest of the set and the resultant 6v with be fine for the 7BP7, it will fit the existing scan coils and focus coils, a temporary IO base and G1 volts from the EHT bleeder network.
I have written up a thread elsewhere about the set but there are many on here that may be interested too so I will add to this thread with pictures and info on the set in due course. At the moment the set is on the bench and I'm restuffing caps and replacing out of tolerance resistors.
One of the interesting things is the EKCO stamp on the RF chassis that clearly shows 9/39 which i assume is a date mark making at least part of the chassis pre-war. As we know we declared war on the 3rd September 1939 which was a Sunday so the factories were not geared up for immediate production stoppage, I'm sure many of these chassis were stockpiled and used after the war. It is odd though they were not re used for the war effort, who knows though.
Cheers,
Trevor.
MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member
This TV rang a bell with me, I remembered David posting about this at Vrat a few yeas back. A quick search and here's the thread from 2013. It contains a few photo's including how it looked as a table top before being returned to a console.
Very nice indeed, look forward to reading your updates ?
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What an interesting set! Strange the cabinet had been cut down.
Move got a soft spot for Ekco, not sure why! I’ve got a T161 on the bench currently, which I must write about soon, and earlier in the year I got an R.S.3 radio that I’d been after for about 16 years! Need to write about that one too before I forget what I’ve done to it.
Regards,
Lloyd
Hi Trevor,
I'd be interested to know what the core of the scan coils is made of? I think that magnetic focusing is simply incompatible with iron cores for reason of residual magnetism.
Peter
Thanks chaps.
I'll not get much of a chance to work on the set today as I've other things to do. Looking at the pictures from 2013 I can see some of the more recent work done. The white spot limiter isn't adjustable and clips peak white even on low contrast, at the moment its disconnected. Both EHT smoothers have been opened up and restuffed, the cans have been araldited together, David has replaced a 2uf cap with a different component but again I've restuffed another can with a modern component so this will be fitted this week at some point. I'm enjoying working on it and fortunately I've a good strong bench!!
Cheers,
Trevor.
MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member
Always a soft spot for the Ekco range of TV’s and radios, we had the agency for the town. Oldest sets that I got to work on were probably 1956-57 at the oldest, so this one is new to me. I moved to that company in 1965 so they were middle 50’s sets were being replaced. Perhaps my favourite sets were the T368 type chassis, I think the T370 had FM radio as well. Reconditioned a T368 for my parents around 1966, excellent picture, I like the cabinet style as well.
Looking forvward to your progress with this TSC30A.
Frank
Ah, yes, I revived a T368 back in 2014, probably about time I fired it up again to see how it is!
Regards,
Lloyd
Pictures looking pretty good on that, I see what you mean about the edge focus though, I can just make out the horizontal lines of the test card getting thicker towards the edge of the screen.
Regards,
Lloyd
Later on today I'm going to re stuff one of the main smoothing capacitors that at the moment has been disconnected and two caps are hanging loose. Also while working on the power supply section I will replace the wax decoupler on the brightness control supply as it looks rather distressed. Before this the CRT will need to come out as it is too dodgy pulling this heavy chassis around with it in place. The tube in these sets are not properly mounted and only when in the cabinet are they secure. Once this work is done the 7BP7 Radar tube will be tried to check the focussing.
Cheers,
Trevor.
MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member
Hi.
Well I'm on course and instead of re stuffing the sound and vision power supply smoother I found a NOS one, ancient nevertheless. Its been reforming most of the day and is doing nicely. I've replaced some badly perished wire and done the last of the out of tolerance resistors. Unfortunately the 7BP7 CRT neck is marginally larger in diameter for the Ekco scan coils so unless I decide to use a different type I will have to abandon that idea.
Cheers,
Trevor.
MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member
The Ekco TSC30A is a development of the pre-war model TSC902 which is housed in a similar console cabinet. The only difference was that the earlier cabinet was presented in a darker finish.
Concurrent with the TSC902 was the table model TS701. Except for a few different valve types this receiver employed a similar chassis. The line output valve is a Mazda AC6/PEN and the frame output is a Mazda PEN45. The two HT rectifiers are Mazda UU5s, UU7 in the post-war sets. EHT rectifier is an U21. U22 in the TSC30/A.
My TS701 has what appears to be a fringe area reception unit, see third picture. An additional RF amplifier stage and the Dickert sound noise limiter.
The CRT is a Mazda 7" Mazda CRM71.
Till Eulenspiegel.
The attachment shows the circuit of the Dickert sound noise limiter. It operates quite differently from the more common series limiter, but like the series limiter the interference spikes have to be preserved in order that the circuit works correctly.
Till Eulenspiegel
So C2 will charge to some negative value, D2 none conducting under normal conditions. A large negative spike will cause D2 to conduct clamping the audio line to the value on C2.
Is this correct? Were there any advantages with this over the series type?
Frank
Hi Frank,
that's exactly how the circuit works. There's an explanation about the workings of the Dickert sound noise limiter in the 1962 Spreadbury book "Television Receiver Servicing". It takes four pages to explain the operation of the circuit.
The attached pictures show the Ekco vision only model TA201. This model was on sale in 1938.
Till Eulenspiegel.
Posted By: Nuvistor
were there any advantages with this over the series type?
The Spreadbury book states that this was the first sound noise limiter circuit and pre-dates the more common series type. I don't think it has any advantages over the series type of limiter.
I've added component values which are according to the book typical for this type of circuit.
Till Eulenspiegel.
I had never heard of the Dickert noise limiter until today.
Every day is an education here. ?
To understand the black art of electronics is to understand witchcraft. Andrew.
It's likely it was invented in-house by Ekco Ltd.
Till Eulenspiegel.
Hi.
So the TS701 you have David has the Dickert limiter on a pre war set? This is very interesting.
Cheers,
Trevor.
MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member
Hi Trevor, no modifications have been done to the TA201 otherwise it is very similar to the TS701. The main difference is that all the components omitted in the TA201 are in the sound output stage.
Vision only receivers were also made by Pye and GEC. An Invicta version of the Pye 817 was also available.
Till Eulenspiegel.
