Very rusty ViewMaster TV

[FERNSEH]

How about this beauty? It's a 12" ViewMaster TV, one of the famous home construction sets of the early fifties.
As you can see from the pictures the chassis is somewhat rusty, just like my wonderful Masteradio T852, remember that one?`

[slidertogrid]

That looks like a challenge! Is the chassis still sound or has it gone really weak ? I had a Sobelette radio that had a thin steel chassis that was very rusty. when I tried cleaning it I went straight through!
My physics teacher at school gave me a load of stuff when he retired including a Viewmaster he had built in the 50s he said it had been the main Tv at home for over 20 years and had only just been displaced by a colour set.
In that time he had modified it for a rectangular tube, ITV and had rebuilt the IF strip with EF80s.
It didn't have a cabinet. and used to horrify my mum when she dusted my bedroom, it was just balanced on a linen basket with a wire up to the picture rail for an aerial.
I loved watching programmes on it with all the valves alight.
One day the lopt started smoking. Once mum realised it didn't work I was under pressure to get rid so I scrapped it for parts, I remember not wanting to but I thought where was I ever going to get a lopt for it?
It was replaced with a Invicta 7070u I caged from a local TV shop, a brilliant set. I still have it 42 years later!
I still regret scrapping the Viewmaster though it was beautifully made..
Rich.

[FERNSEH]

Hi Rich,
The chassis metalwork looks really awful, but in fact it's only surface rust, it's quite solid. I'll have to be very careful with the clean up of the RF chassis, it's not an easy unit to work on. The timebase chassis however can be completely dismantled, the metalwork de-rusted then followed by reassembly.
It is possible to detach the RF unit from the timebase chassis, this will help to make the job easier.

DFWB.

[Brigham]

I was about to ask "Are you going to have a go..."
I never learn, do I?

[Heatercathodeshort]

Hello David,
Now why did you have to obtain that Viewmaster and keep me up late tonight? It is not too bad and should be an easy fix.

I have the full viewmaster service data, modifications and plans. If you want them, please let me know.

I have had this channel 3 chassis version hanging around the workshop for years! I didn't bother with it as I didn't want to play around with the channel selector on the Aurora and maybe break the switch..I decided to pull it out early this evening and give it a go.

I also robbed the Mazda tube for another project so thought it might be fun to fit a Dumont 5FP7 tube. of WW2 vintage that I have had for very many years.
This tube has a 5" screen, magnetic focus and deflection, 6.3v heater, a standard neck diameter and an octal base. It also has a double layer, very long persistance screen....At least five minutes as can be seen from the picture. On a test card it looks fine but on moving images, well you can imagine. Picture looks like a watercolour that has been left out in the rain.

Chassis faults were just caps in the thyratron timebase generators and output stages. Just a bit of fun but the original constructor made a first class job of it. I also had to fit an 'ELAC' focus assembly in place of the original as it was not suitable for a tetrode tube and gave poor focus.
Hope you sort it out. John.
PS The second picture shows the afterglow, three minutes after turning off!

[Nickthedentist]

Originally Posted by Heatercathodeshort

It is not too bad...

That's not the reaction I was expecting from you, John

[Heatercathodeshort]

The viewmaster was without doubt the very best home constructed design that was available.

The construction pack and data is excellent with good technical back up. I think I read in Practical television that around 30.000 had been built and were in regular use.

The circuit was very straightforward and if care was taken with construction the results were without doubt very good matching many commercial receivers of the period.

The chassis could accommodate almost any of the popular 9" and 12" triode or tetrode tubes with very little modification.

The RF gain is very good and a pre amplifier circuit was available if you resided in one of the many 'fringe' areas.

Many of these receivers were constructed by guys that had been involved with Radar during the war and much of the circuitry must have been familiar to them.

David, you will probably discover that the under chassis is relatively free from rust. Mine has some on the top but it was easily shifted with a pot scourer, the type that Tesco sell in a five pack for around 20p. Not too harsh and they have many uses.

I bet the original constructor, probably long departed, would be very amused
to see our entertainment with a couple of Viewmasters 60 years on.

The LOPT is very reliable and has provision for a Mullard EY51 EHT rectifier.
Many were fitted with the massive STC stick rectifier comprising hundreds of metal oxide discs in a paxolin tube.

A picture soon I hope. Just a last thought. If the tube is duff you could nick the one out of the nastyradio..

A couple of better pictures taken this morning and one of the spooky afterglow from the 5FP7.
Regards, John.

[FERNSEH]

Before I even attempt to power up this set the line output transformer must be warmed up to drive out any moisture. The favoured method is to supply the overwind with about 20 to 30 volts in order to bleed a current through the windings, this warms up the transformer to a temperature which is similar to normal use.
it's an easy enough task to remove the transformer for this procedure. it has to be removed anyway because all that chassis surface rust has to removed.

DFWB.

[HamishBoxer]

Very sad that pieces of history are badly stored most of the time before being found by an enthusiast.

Yes I wondered wether the loptx would survive.

[Heatercathodeshort]

Good idea David. These very simple transformers produce around 7kv of very well regulated EHT.

Mine has no cabinet and thinking about it I might make a few base adaptors and use the chassis to picture test any tubes with 35 or 38mm neck diameters. A few pre cut wooden blocks will suffice as support for the various CRT shapes and setting up would only take a few moments.

It would not alter the chassis in any way and maybe a cabinet will become available in the future returning it to a complete receiver. Most odd items seem to turn up if you wait long enough! Regards, John.
PS Totally agree Hamish but at least David has got it and if anyone can get a picture on it I'm sure David will manage it. They don't call us Laurel and Hardy for nothing...

[Heatercathodeshort]

Originally Posted by Nickthedentist

That's not the reaction I was expecting from you, John

Well really.....What can one say?

Just a note. My View Master is tuned to channel 3. It came complete with all the original construction notes and the extra sheets for the Kirk o Shotts transmitter but the envelope is marked Brighton, 'Truleigh Hill'.

This was the first relay station [I think] picking up the AP transmissions and retransmitting them to the Brighton area on channel 3 later to be superseded of course by Rowridge, the high power transmitter on the Isle of Wight. I think it opened in 1952 two years before Rowridge.

You should be able to retune yours David from channel 2 to channel 1 simply by retuning the cores of the RF stages. Maybe worth a go when you have eventually raised it from the dead. John

[FERNSEH]

Hi John,
The construction of the ViewMaster cabinet is very simple. i'm sure I could knock up cabinet for your chassis.

DFWB.

[Heatercathodeshort]

Thanks for your kind offer David. Maybe some time in the future.
Oh, I have a few 'OUTSPAN' orange boxes here that we used to use as bedside tables in the 50's [Complete with middle shelf] If your short of timber, maybe they could be cobbled a bit to fit. Thanks, John.

[Peter.N.]

That takes me back, one of my schoolteachers built one of these in the '50s.

Peter

[FERNSEH]

One advantage of building your own TV set from a kit of parts was that there was purchase tax to pay. The tax on TVs radios and radiograms was pretty punitive in those days. One just has to look at the price lists of electrical goods on sale in the early 1950s.

Hi John, I haven't got any orange boxes but there is a sheet of plywood outside in the back yard. I reckon I could make you a cabinet from that.
Real MacArthur Park stuff, like the cake it was left out in the rain.

DFWB.

[Heatercathodeshort]

Yes, Purchase tax at 66%. Can you believe that. The problem with home constructed chassis was always the cabinet.
Electronics and carpentry did not always go well together resulting in a horrible mess of nailed together wood with a crt aperture hacked out with any old saw that was capable of cutting.
It was only the prestige of owning a television receiver of any kind that the lady of the house allowed such contraptions anywhere near her well dusted living room, rather like the Edwardians with the first horn gromophones.
The View Master arranged to have reasonable cabinets built by professional companies to case a chassis that was worthy of the effort.

I don't like the sound of that 'cake in the rain' plywood. Seasoning is one thing David but peeling old plywood is a bit of an insult for this cracking specimen of a View Master...
I have an old Decca Decola here that looks as if it will make a good donor cabinet. [with a few mods.] We can work the details out later.
Keep the old Plywood for a bird table. Regards, John.

[Heatercathodeshort]

I have been playing around with the View master this evening.
One thing I forgot to mention was the excellent sound obtained from this chassis. Not a trace of vision buzz and the KT61 sound output valve is driven to full output. All this with just one sound RF stage. It certainly was a very well thought out design.

Actually the moving picture is quite acceptable with the very long persistance tubes. This one was taken with a Dumont 7" type 7BP7, CRT that is very similar to the 5" 5FP7 fitted at first.

The blue picture on the back of the tube is bright and finely focused. Such a pity about that thick afterglow coating at the front! Must not moan..Lucky to have what we have got. The picture brightness even with a reduced contrast setting is good even with full workshop lighting. Regards, John.

[FERNSEH]

Originally Posted by Heatercathodeshort

Yes, Purchase tax at 66%. Can you believe that.

66 per cent! How could the radio and television industry survive with such a punitive tax?
It made sense to make your own TV set, in fact you'd still save money even if someone else assembled the set for you.

DFWB.

[SteveCG]

I didn't realise that Purchase Tax was quite that high (I wonder for how long) . It certainly explains the proliferation of articles in Wireless World, Practical wireless etc on home construction. Especially those involving EF50s and ex-radar chassis with VCR 97s.

Did commercially made TV aerials have the same tax rate - in which case I wonder what aerial designs were suggested to complement the ViewMaster?

[FERNSEH]

I don't think aerials attracted purchase tax because such items would have been considered as components and accessories in the same manner as the parts that were used in the ViewMaster.

However, valves and CRTs did have purchase tax although I seem to remember Parliament changed the rules on replacement CRTs, sometime around 1957/8.
No tax on rebuilt CRTs. Mullard introduced their range of "Luminar" tubes and Mazda "Relife".

DFWB.