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B&W TV Marconiphone VT161

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PYE625
(@pye625)
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As this set was no more than a few minutes drive away, I could not really say no. Well, that's my excuse anyway.

It came from an attic in the village of Stuntney, near Ely Cambs, where it has resided for many a year no doubt.

Upon initial examination it appears to be in very good shape. A few repairs have probably been done in the past, notably to the mains dropper. The CRT read almost zero emission initially, but is slowly awakening after it's long slumber. No attempt will be made to rejuvenate it with the B&K until I am sure the set can be repaired to working order. Even then, I may wait to see if it improves with use.

Here are a few snap's to look over...

IMG 5925 50
IMG 5923 50
IMG 5926 50
IMG 5927 50
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Topic starter Posted : 27/06/2021 8:03 pm
LSmith, turretslug, Red_to_Black and 2 people liked
Lloyd
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Nice telly, and that is a very good excuse for buying it!

 Regards 

Lloyd 

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Posted : 27/06/2021 8:34 pm
PYE625 liked
Till Eulenspiegel
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Absolutely brilliant sets. The handwired chassis is something rather special. Apart from a version made for rental companies, British Relay? the chassis was also used in many export 625 line receivers, hence the all those spare holes on the IF deck.  The special fringe area Ferguson 505T has similar chassis metalwork. In my set the mains dropper resistor needed replacement and it was found the slab like dropper employed in the 1961 Ferguson 725T has the almost the right values. Brackets were made for the new component.   The CRT needed replacement and I was fortunate to have an unused Mullard AW43-80Z. This was a modified version of the older tube and is fitted with the gun assembly from the 110 degree AW43-88. The CRT base is the 8pin B8H type. No ion trap required. The Marconi VT161 was released late 1958 and was still available in 1960.  

Till Eulenspiegel.

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Posted : 27/06/2021 8:39 pm
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PYE625
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With the chassis removed from the case, here are a few more pic's along with a fibre item found partially stuck to the chassis with dried up tape. Can you guess as to what it's purpose was for?

IMG 5931 50
IMG 5933 50
IMG 5928 50
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Topic starter Posted : 27/06/2021 9:51 pm
Lloyd
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Some sort of insulator? Or maybe a heat shield?

 Regards 

Lloyd 

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Posted : 27/06/2021 10:39 pm
Till Eulenspiegel
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I'm sure that is the template for setting the position of the line linearity sleeve on the neck of the tube. Although there is no mention of such a device in the VT161 service manual or in the 1959/60 Radio and Television book.

The attachment shows the line linearity adjustment for the Ferguson 305T and was taken from the 1957/58 R & T servicing book.

Line Linearity Adjustment
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Posted : 27/06/2021 11:57 pm
PYE625
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You are quite right Till, and the instructions from the Marconi service data are very similar to the Ferguson....

template
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Topic starter Posted : 28/06/2021 6:46 am
Till Eulenspiegel
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And yet the ten page service manual I have here makes no mention of the linearity sleeve.

Till Eulenspiegel. 

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Posted : 28/06/2021 10:31 am
PYE625
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No because there is a service data supplement consisting of two additional pages that cover schedules B, C and D. Schedules C and D have the linerarity sleeve apparently. I need to check which schedule this set is.

I downloaded it from Paul Stennings site as an instant download...

https://www.service-data.com/

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Topic starter Posted : 28/06/2021 5:03 pm
PYE625
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Guess who can't spell "linearity". 🙄 

Anyone fancy some good old genuine Fenland dust from the 60's ? I have plenty. I might put it on ebay if there are no takers here... 😆 

This chassis was smothered and most of it has almost filled up the hoover bag. I imagine the set gave many hours of happy viewing and well into the 70's by my guess.

Have a look at these pic's and you will see what I mean, a Willow Vale PCL82 in the frame stage installed after April 1972. (Could have been a tad difficult to install it before then maybe?)

Also, the place where the linearity template is kept.

Still not found a mark bearing the schedule of the chassis, so will assume for now it is A.

IMG 5935 50
IMG 5936 50
IMG 5938 50
IMG 5942 50
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Topic starter Posted : 28/06/2021 6:34 pm
Jayceebee
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Posted by: @pye625

Guess who can't spell "linearity". 🙄 

Some people even struggled to say it. Linarity was heard quite often. 😊  

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Posted : 28/06/2021 6:44 pm
PYE625 liked
Katie Bush
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Posted by: @jayceebee
Posted by: @pye625

Guess who can't spell "linearity". 🙄 

Some people even struggled to say it. Linarity was heard quite often. 😊  

I've even heard it pronounced as "Line'Arity" - Though that was not in television circles. We had results which were pronounced as not "line-are" and "Line'arity of results not important at this stage".

 

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Posted : 28/06/2021 7:59 pm
PYE625
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After a bit more of a clean, the components can now at least be seen.

IMG 5940 50

The "Fireball" tuner can be seen just above the mains dropper in the photo. This is the first time I have seen one and after making some notes of the connections, removed it from the chassis. The reason for this was to open the tuner and give it a gentle clean and service.

It was fairly simple and essentially a light re-greasing of the moving parts, plus using Servisol switch cleaner to remove slight oxidation of the many switch contacts, it was re-assembled. Previously, the fine tuner control was rather stiff and removal of the old dried grease on the tuner switch shaft solved this. At least it is now mechanically good, time will tell if it is electrically ok.

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Topic starter Posted : 28/06/2021 8:39 pm
Till Eulenspiegel
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The first attachment shows the main dropper currently fitted in my VT161.  The component was intended for use in the Ferguson 725T and had been in my parts stock since the early seventies. The brackets were bought from a local hardware shop.  Since these pictures were taken the tuner has gained a screening can.

Marconi VT161 dropper 2

The set was made in 1958 and the serial number is 1958.

Marconi VT161 SN 1958

Till Eulenspiegel.

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Posted : 28/06/2021 9:30 pm
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PYE625
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With the screening cover off the tuner, it looks a bit like a round hedgehog !

In time, I may consider re-winding the dropper in this set. It will be a bit easier than the Murphy I did as the sections that are open circuit are of less resistance. The dropper itself appears of similar construction with lugs to attach the new resistance wire.

The set, at a guess, is mid to late 1959 as the main electrolytic has Jun 59 on it.

IMG 5929 50
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Topic starter Posted : 28/06/2021 9:46 pm
Till Eulenspiegel
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30974 Looks like they made quite a few Marconi VT161 sets and the near identical versions for rental companies. The sets were rumoured to have been made at the Hainault, North East London works.

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Posted : 28/06/2021 10:14 pm
Nuvistor
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Fireball tuners, possibly one of the easier tuners to clean the contacts on.

 

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Posted : 28/06/2021 10:22 pm
PYE625
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The chassis really is quite filthy, plus nicotine stained to a degree, so this evening I have removed the CRT to aid proper cleaning of it and the chassis. I can confirm that a linearity sleeve is fitted so this must be of a later schedule, as mentioned earlier.

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Topic starter Posted : 29/06/2021 9:50 pm
PYE625
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Last night I typed in "mains dropper" on ebay. I was quite surprised after a brief scroll to find an exact dropper replacement for this set, so I thought "Ill have that blighter".

s l1600

This evening I removed the LOPT and gave the compartment a good clean. The LOPT itself looks and test's in good condition. No molten big lumps of tar. However, C67 an 800pf 5KV capacitor mounted on the LOPT does not look so good. It is a LEMCO and has a crack just past the LEM legend. Again, amazingly, the exact same type is available on ebay at modest cost so I have bought that too.

IMG 5943 50
IMG 5945 50

 

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Topic starter Posted : 30/06/2021 8:00 pm
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PYE625
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It's a well known fact that aged metallised paper capacitors such as the Hunts mouldseal type can be leaky and out of spec. There are a fair number dotted about this set as might well be expected.

One such capacitor is C68 that couples the line scan coils via the width coil to the LOPT and is, in this chassis, meant to be 1uf. If I had not measured it myself, I would not believe that it is in fact almost ten times it's rated value. This must be replaced.

IMG 5946 50
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Topic starter Posted : 30/06/2021 9:19 pm
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