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Old 9th Sep 2020, 10:05 pm   #1
1100 man
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Default Dynatron TV32 'Marlborough'- Future project!

Going to the NVCF or BVWS auctions can be a dangerous game- you often come home with things you didn't expect! This TV is a case in point.

A long time ago, probably the best part of 20 years when the NVCF was still at the NEC, I spotted this monster console TV in all it's faded grandeur. It had seen better days: The walnut veneer was in a poor state and the doors had fallen off and there were quite a few woodworm holes in the front.

However there was something appealing about it and I looked at it several more times during the day. Luckily the seller wanted 35 quid for it, so I could easily talk myself out of buying it! Unfortunately I got chatting to the chap and despite my protestations that it was far too big, he ended up giving it to me for free on condition that I restored it! He really didn't want to take it home either!

Well, I could hardly refuse, so into the car it went. It was seriously heavy! Back home, it took two of us to get it into the house and then to get the complete chassis with tube onto the kitchen table. There it stayed for the next two years until I moved house as I couldn't move it on my own!

It has a very large, heavy gauge steel chassis that runs the full width of the cabinet and almost the full depth. The massive 90 degree 21" tube is attached to this with an equally thick angle iron frame. Just to get the weight up a bit more, there is a huge mains transformer. The whole lot is painted in green Hammerite type paint which seems odd for a TV chassis.

It's quite remarkable, especially in the UK to have a mains transformer in a TV. I seem to remember it uses a combination of 'E' series & 'P' series valves. There are more than enough valves in it to use a conventional series string and mains dropper and I can see no benefit in using a transformer.

Also of note is the push pull sound output, using two EL84's (I think) driving a very large speaker.

This really did seem a 'no expense spared' TV especially considering the quality of the figured walnut veneer cabinet. The set came with a sales brochure listing the whole model range. The 'Marlborough' was listed at 203 Gns- eyewatering in the late '50's!

Since being relegated from my kitchen table, the set has spent the last 10 years in a very dilapidated barn which is rapidly being consumed by woodworm and wood rot. Luckily, the woodworm seem to have so much to eat in all the structural timbers in the barn that they don't seem to have noticed the various TV's stored in there!

I seem to remember I got to the stage of getting a picture on it but I didn't have a proper standards converter back then so couldn't really progress much further.

I never managed to track down a circuit for it so if anyone has one I would be most interested in a copy of it. Looking at the pictures of the chassis, the LOPT looks very EKCO to me. I don't know the history of Dynatron, so would they have made the whole thing, or bought the chassis in from another manufacturer?

I still have every intention of one day honouring my commitment to the chap that gave it to me and actually restoring it to it's former glory. Unfortunately, I don't think that will be any time soon!

All the best
Nick
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Old 9th Sep 2020, 10:19 pm   #2
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Some history, Dynatron sold to Ekco 1954, the Hacker bros stayed until 1959 before forming Hacker Radio.
http://www.dynatronmuseum.org.uk/History.htm

They probably needed the mains transformer to power the push pull audio stage, it’s a large TX so it probably powers other parts of the set. The tuner, Metrosil and LOPTX are of Ekco stock.

https://www.vintage-radio.net/forum/...d.php?t=108863
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Old 10th Sep 2020, 1:43 am   #3
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Hi Nick,
This will a very interesting restoration project. The TV32 was the subject of my topic started in August 2014. The set is the result of collaboration of Dynatron and Ekco design teams. Expect the picture and sound reproduction to be of a very high standard.
I haven't the full service manual but do have the circuit diagram if you need it.

DFWB.
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Old 10th Sep 2020, 10:55 pm   #4
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Hi David,
I would certainly appreciate a copy of the circuit- it would be interesting to see what circuit techniques they have used. I imagine there will be some sort of interlace filtering? Did it have 'spot wobble' as fitted to other Ekco sets?

Interesting that even on a set of this quality, there is no black level clamping or DC feed to the CRT. This certainly can't be down to reasons of cost. I am more and more convinced that manufacturers actively decided not to maintain rigid black level for a variety of reasons in nearly all UK receivers. I get the impression that it was considered an undesirable feature, rather than down to cost cutting.

Thanks for the link, Frank. Rather amazingly, I was unaware of the link between Dynatron, Hacker & Ekco! I am now a little wiser.

Here's a picture from the sales brochure showing the Marlborough and the other TV's in the range. I can't believe many were sold at that price!

Cheers
Nick
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Old 11th Sep 2020, 12:26 pm   #5
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Default Re: Dynatron TV32 'Marlborough'- Future project!

I'll be interested to see how you get on with this project. The sound should be excellent with 2 x ECL82s in PP and a generous 10" x 6" speaker. A great improvement on the later Dynatrons where the chassis was nothing more than a bog-standard Pye/Ekco unit with no circuit enhancements, the only difference being a larger loudspeaker.
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Old 11th Sep 2020, 4:37 pm   #6
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Default Re: Dynatron TV32 'Marlborough'- Future project!

What a fantastic set Nick!

How have you resisted not restoring it for so long? Guess it’s got a Mazda airbag in it, so let’s hope it’s capable of producing a reasonable raster.

Anything with the input of Ron & Arthur Hacker will be excellently engineered. Now that you’ve let the cat out of the bag, we’ll all be nagging you to get on with it!

Cheers.

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Old 11th Sep 2020, 6:10 pm   #7
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Quote thermionic: "Guess it’s got a Mazda airbag in it, so let’s hope it’s capable of producing a reasonable raster."
The Dynatron TV32 employs Mullard valves and and an MW53-80 CRT.
If Ekco designers were involved with the design they had steered clear of Mazda valves and CRT.
It could be that Dynatron had chosen Ekco scanning components purely on a supplier basis.

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Old 11th Sep 2020, 6:34 pm   #8
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Default Re: Dynatron TV32 'Marlborough'- Future project!

I haven't seen a tube in a cradle since the Ekco T283 I used to have! Looks like a huge beastie to manhandle....
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Old 11th Sep 2020, 10:16 pm   #9
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Quote:
Originally Posted by 1100 man View Post
Interesting that even on a set of this quality, there is no black level clamping or DC feed to the CRT. This certainly can't be down to reasons of cost. I am more and more convinced that manufacturers actively decided not to maintain rigid black level for a variety of reasons in nearly all UK receivers. I get the impression that it was considered an undesirable feature, rather than down to cost cutting.
The attached book excerpts, one from Davies (“Understanding Television”) and one from Hutson (“Television Receiver Theory”) provide some background as to why full black level retention was often avoided in domestic receivers.

One reason was that if done, it required better EHT regulation than was the norm for domestic receivers in order to avoid other deleterious effects. As Hutson put it: “The partial loss of the d.c. component is the lesser of two evils, and involves a commercial compromise. In terms of absolute picture fidelity both complete retention of the d.c. component and a well regulated e.h.t. system are necessary.”


Cheers,
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Old 12th Sep 2020, 4:44 am   #10
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Quote:
Originally Posted by Edward Huggins View Post
A great improvement on the later Dynatrons where the chassis was nothing more than a bog-standard Pye/Ekco unit with no circuit enhancements, the only difference being a larger loudspeaker.
I was of the impression that the later TV50 chassis was modified by Dynatron to include AFC for both TV (via the sound channel) and FM. Was this though an Ekco original feature? The sound channel used a double diode acting as both an AM demodulator and an AFC discriminator.

Cheers,
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Old 12th Sep 2020, 7:54 am   #11
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Quote:
Originally Posted by FERNSEH View Post
Quote thermionic: "Guess it’s got a Mazda airbag in it, so let’s hope it’s capable of producing a reasonable raster."
The Dynatron TV32 employs Mullard valves and and an MW53-80 CRT.
If Ekco designers were involved with the design they had steered clear of Mazda valves and CRT.
That’s good news, I would imagine that based on that information, Dynatron had the main input into this sets design and development.

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Old 13th Sep 2020, 9:39 pm   #12
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Quote:
Originally Posted by thermionic View Post
What a fantastic set Nick!

How have you resisted not restoring it for so long? Guess it’s got a Mazda airbag in it, so let’s hope it’s capable of producing a reasonable raster.
Hi Simon,
The weight of the whole chassis & tube is a big factor- I can't lift it by myself. It's one of those sets that needs a workbench to itself where it can be worked on as and when. I've only had rather makeshift repair facilities in recent years. One day I plan to build a decent workshop so I can finish all my 'works in progress'!

To be fair, I've never had much trouble with Mazda tubes. Most of the tubes in the sets I get are generally low emission and just need a gentle wake up with the B&K. This seems to affect all the makes equally. I've not had other faults such as O/C heaters or shorts in any make of tube either. Now LOPT's on the other hand....!!

Synchrodyne- many thanks for providing the information on the black level clamping issues- most interesting and it shows that there were good reasons for not maintaining rigid black level. I always thought there was more to it than cost cutting!

All the best
Nick
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Old 14th Sep 2020, 12:55 am   #13
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Here is another item, which ascribes AC-coupling of the video as an anti-flutter device:

PTV 195802 p.330 Flutter Reducer.pdf

I think that this item about the Dynatron “Chippendale” 21-inch TV receiver probably refers to the TV32 chassis:

PTV 195802 p.342 Dynatron TV.pdf

It was stated to have gated AGC (presumably black level AGC) and stabilized EHT. That being the case, the use of partial DC coupling was probably not done to make life easier for the EHT system, but perhaps to some provide anti-flutter performance. Assuming that the EHT was stabilized to the point where full DC coupling was possible, then one may wonder why, in such an upmarket receiver, there was not a preset control that would allow a customer choice between full and partial DC coupling, with the latter recommended where flutter was as issue, the former for users who preferred that the black level stayed where it was put.


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Old 16th Sep 2020, 11:46 pm   #14
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Default Re: Dynatron TV32 'Marlborough'- Future project!

The earlier thread on the Dynatron TV32 is here: https://vintage-radio.net/forum/showthread.php?t=108863.

The anti-flutter circuit is mentioned in post #14 therein.

It also appears that the RF side of the circuitry was legacy Dynatron, whereas some other aspects were from Ekco practice. That makes some sense. In respect of its radiogram products, Dynatron’s strong suit was the RF side. On the AF side, both control and power amplification, its circuitry up to 1955 could be described as being fairly ordinary, and afterwards as derivative. In its 1955 Ether Pathfinder series, the T10 tuner chassis largely followed previous Dynatron practice, whereas the TC10 control unit and LF10 amplifier look as if they were derivatives of the Osram 912. (And the later LF20 amplifier was known to be a Mullard 5-20.)


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Old 17th Sep 2020, 12:03 pm   #15
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Hi nick
That looks even flakier than my 2k!, i think it needs to be loved, perhaps if you get more permanent facilities it'll get some treatment, looks very rare and interesting.
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Old 18th Sep 2020, 11:01 pm   #16
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Default Re: Dynatron TV32 'Marlborough'- Future project!

Quote:
Originally Posted by Synchrodyne View Post

I think that this item about the Dynatron “Chippendale” 21-inch TV receiver probably refers to the TV32 chassis:
Yes, it certainly would seem to be the TV32. I assume they are using the word 'Chippendale' as the whole range is built into luxury wood cabinets.

In the 'anti- flutter' article, they also talk about the introduction by manufacturers of mean level AGC rather than the superior 'gated' AGC.

Quote: "As quite a number of viewers like to increase the brightness during night scenes of a play... Manufacturers have quietly introduced [mean level AGC] to their sets and since no 'hue and cry' has been raised by the 'black level fanatics', nobody seems to have noticed any difference!"

Yet more evidence to suggest that the viewing public did not appreciate rigid black level and actually preferred an increase in brightness during dark scenes.

Quote:
That looks even flakier than my 2k!, i think it needs to be loved, perhaps if you get more permanent facilities it'll get some treatment, looks very rare and interesting.
Hi Greg,
I've always had a preference for large screen sets and 21" was about as big as it got in 1958! The down side of course is the size and weight of the thing!

The cabinet is actually pretty solid and even the rear cover is intact. I just need to polish up my veneering skills! This will be a very imposing set when fully restored and is definitely on my 'to do in the future when I get a decent workshop' list!

With 23 valves, it's got quite a few more than any of my other sets!

All the best
Nick
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