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Quick TV cabinet refurbishment 60s style.

 
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Quick TV cabinet refurbishment 60s style.

Post by Till Eulenspiegel » Sat Apr 12, 2014 12:19 pm

Imagine what it was like working in the TV rental trade fifty years ago. You've got to prepare a certain set for re-rental, and fast! Here's an example, this Defiant TV is ready to go but the cabinet needs some work to make it a more viable rental proposition. Sets that were over three years old could be rented out without accepting an advance payment of thirteen weeks.

Let's see how fast I can tidy up this set.

Till Eulenspiegel.
Attachments
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Re: Quick TV cabinet refurbishment 60s style.

Post by Till Eulenspiegel » Sat Apr 12, 2014 1:07 pm

Forty minutes later and that's the surface prepared for French polish.

Till Eulenspiegel.
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000_9965.jpg

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Till Eulenspiegel » Sat Apr 12, 2014 3:49 pm

First application of French polish. It certainly brings out the grain of the wood.

Till Eulenspiegel.
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Re: Quick TV cabinet refurbishment 60s style.

Post by Katie Bush » Sat Apr 12, 2014 9:10 pm

Hi Till,

Wow, that is a real smartner on this set, and what a handsome set too.. Not over cluttered with buttons and knobs, functional but at the same reservedly smart and attractive. :aad I'll bet it's a real Plessey to work on. :aap

Now, I just have to say, I like it! :bba

Marion

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Till Eulenspiegel » Sat Apr 12, 2014 9:25 pm

Hi Marion,
The cabinet top just needs "spiriting off" and then it's ready for delivery tomorrow. So far I've resisted the "just plug it in" routine.
This set has a 90 degree CRT, a Mazda CRM173, magnetic focus. The Rediffusion version, the CA174B has the Mullard AW43-80 electrostatic focus CRT.

Till Eulenspiegel.

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Katie Bush » Sat Apr 12, 2014 9:43 pm

Hi Till,

I have a variac...... :bba

I have to say though, it really is a smart looking set, and my guess would be that it's the same chassis as my table top Defiant 17" model.. Mine needs a look at to find the cause of its picture shrinkage, but otherwise, it worked from first light with excellent geometry and focus.. Picture quality was aboslutely spot on with first rate brightness & contrast, and perfect lock on both timebases.

I think Plessey made a first class job of this chassis, and I'd guess that it was the ideal candidate for rental sets. :aad

Marion

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Till Eulenspiegel » Sat Apr 12, 2014 9:53 pm

Hi Marion, Servicing data for this set can be found in the 1958/59 R & T servicing book, on pages 344,345 and 346. Model 7109.

Till Eulenspiegel.

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Katie Bush » Sat Apr 12, 2014 10:02 pm

Hi Till,

Looking at as I type. :aad

Marion

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Till Eulenspiegel » Sun Apr 13, 2014 12:19 am

Another Defiant TV set which employs a similar chassis as the console 7109. This is an early version of the Plessey chassis. Made in 1956 this set, model 1410X employs a 14" Mazda CRT type CRM143, a rather curious tube as does not have a aquadag coating and for that reason a separate EHT smoothing capacitor is required. A later CRT, the CRM144 has the aquadag. Note the very early version of the PY32 HT rectifier, it has the ST shape bulb. Later PY32s have a tubular bulb. the PY32 was replaced by the PY33 which has a special cathode coating which offers a lower A-K voltage drop.
The upper rear batten needs replacing. Sort of split in two. I'll make a new one.

Till Eulenspiegel.
Attachments
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000_9970.jpg

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by crustytv » Sun Apr 13, 2014 12:23 am


 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Till Eulenspiegel » Sun Apr 13, 2014 12:49 am

Hi Chris, Your 7109 is the later version and has the excellent electrostatic focus Mazda CME1702 CRT which replaces the CRM173 employed in the set which is the subject of this topic.
The final model in this series, the 719 used a PCL84 as the video amplifier.

Till Eulenspiegel.

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Till Eulenspiegel » Mon Apr 14, 2014 3:26 pm

The Defiant TV set was delivered yesterday. We've learnt something else about this set, it has FM radio. The turret tuner has three positions for BBC Home, Light and Third.
The circuit for this set resembles that of the Regentone T21FM and information about that set can be found in the 1958/58 Newnes Radio and Television book. The only difference between the Regentone version is choice of valves, Mullard instead of Mazda.

Till Eulenspiegel.

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Mikeymushradio » Mon Apr 14, 2014 4:36 pm

Nice job on the cabinet Till, did you resist the urge to plug it in?

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Katie Bush » Mon Apr 14, 2014 4:38 pm

Hi Till,

This is a really nice set.. Many thanks indeed. :aad

I haven't really looked in at any depth, but I had a good peep before I put the back, back on, and I'm impressed with the build quality of the cabinet, which is excellent.

The chassis has a lovely layer of dust which reveals nice clean metalwork beneath.. It shows no sign of previous repairs (as yet anyway), but I am itching to replace that particular cap you referred to lastnight, and see what happens.

I'll probably kick off with repairing the channel knob, even if just to simplify the task of knowing which channel we're on!

Now, for everyone else' benefit... We just had to give it the beans, didn't we?

So, we took a hybrid approach to this... Not my own usual reserved slow wake up, but then not full on power approach neither.

In our eagerness to see first light, "we" skipped the snipping out of the filter cap :aao , and brought up the volts on the variac over about ten or fifteen minutes (well, Marc and Till did!) until there were signs of life.. I have to confess, I couldn't really hear the line whistle (tinnitus and all that), but there was a healthy flame of EHT from the rectifier top-cap.. A minute or so of Till adjusting the ion trap, and voila! we had a raster - First light.

Next job was to bring on the Aurora, and find a channel, and there we had it, a bit distorted (frame linearity) but bright and healthy testcard. *** More on the electronics later ***

Prior to this, we had a little French polishing lesson - courtesy of one of my cats! :ccg and that is an artform in its own right.. I know Marc has done this kind of work before, and watching Till at work on the cabinet was quite absorbing and interesting, just to see that shine reappear from the polish (naughty puddy-tat, put paw marks all over it) with nothing more than methylated spirits and linseed oil, Till recovered the shine. :)

In the fulness of time, I will begin a thread on this set, and will see how well I can restore the electronics, though it shouldn't be difficult.

Marion

 
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Re: Quick TV cabinet refurbishment 60s style.

Post by Till Eulenspiegel » Mon Apr 14, 2014 5:45 pm

Mikeymushradio wrote:Nice job on the cabinet Till, did you resist the urge to plug it in?


Hi Mike,
We did this one properly, used the variac and brought up the supply voltage slowly.

The picture is compressed at the top and this fault will almost certainly be due to a leak in C41, (C37 in the Regentone version). See attached circuit diagrams. A leak in this capacitor will cause the negative voltage present in the blocking oscillator appearing at the control grid of the output pentode.
Worth noting that the Regentone has two frame linearity controls, it should be possible to modify the Defiant to this spec. Perhaps the designer wished to optimise the frame linearity on the 21" CRT receiver.

This was one of the most reliable 1950s TV chassis, although I'd reckon the RGD Deep 17" was even more reliable.

Till Eulenspiegel.
Attachments
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