Pye tv - LV30 ?

[peter10tv]

I told you so! You are also suffering from the same disease as most of us. Once you have started you just can't let go. I can't wait to hear the next installment of the journey. How long shall we say, a couple of weeks?
Regards
Peter

[HamishBoxer]

Richard,without going o/topic was it yourself i bought a Lotus radio off?? Certainly remember Bella if so.

David

[slidertogrid]

Hi David, I don't ever remember a lotus radio. I did sell a couple of early sets some years back some of which were collected by fourum or BVWS members.
But they were Ekco, Marconi and one that was very deco.. but I can't remember the make of that one!
Yes I certainly have the old telly bug, it doesn't help when my mate, Mick has a workshop full...
I am keen to get the Pye working, I have started a fund to buy another converter, but I won't buy one until I know the Pye is repairable as there is no knowing what the damp storage has done to the coils, transformers, lopt, etc.
Then there is the tube, I can see it has no ion trap so (if it has any emission) I bet it has a burn! I might see if I can test the tube and do a few resistance checks before I go too much further with it!
That said if it is beyond reasonable repair I havn't lost much!
Cheers , Rich.
Edit: The set was a Radio instruments "Airflow".

[HamishBoxer]

Sorry Richard!that was it the "Airfow", its now in Scotland.Certainly remembered Bella the boxer and we have Hamish now nine.

Thats me,no more off topic.Thanks for reading.

David

[MickMcmichael]

Well it's still here with the ERT service sheet awaiting attention.

I keep walking past it and wonder whether it would work if I ....

No don't worry. I won't.

[HamishBoxer]

It will work Mick,did one of these years ago and it all went fine.

[Heatercathodeshort]

Plug the Bxxxxy thing in!
Hello Mick,
The tube will probably have good emission but may have an ion stain. This is all part of television history and it does not bother me at all.
Keep the EHT up to scratch and I doubt if it will be all that noticable. Those early Mullard tubes were very sturdy things.
Like your approach with the paint brush and vacuum cleaner. That is all that is required. The LOPT has become a weak point with these little receivers but they can usually be rewound by Mike Barker.
Regards, John.

[MickMcmichael]

Well John, you've probably gathered it's not my set. It is sitting on my bench as it's probably the safest place for it to be until Rich's capacitors arrive and we organise another one of our "telly days" to get the thing fired up.

Shouldn't be long now. The set will be first in line for attention and I've got a few gems to fill out the day if the LV30 turns out to be a damp squib.

The dropper has been the centre of conversation due to its poor state. Do we work out and replace almost every section to keep it original or, do we just work out the necessary values for the mains voltage around these parts? We're tempted by the latter but I think a set of this age really must be kept original if possible. I've looked through my vast collection of droppers and there isn't an LV30 type in the box so the former could well be the initial choice.

Watch this space and all will be revealed ....

in due course. Come on Rich, where's those caps ?

[Heatercathodeshort]

Replace the whole dropper with RS 'polo mints' on a length of studding. Stick to the original values [within a few ohms] and set the mains tapping for 240V. The droppers were crammed into a small space on these receivers and tended to overheat the back panel.
You can see my example working here. http://www.youtube.com/watch?v=wJL6-hyjYiA
The picture quality does not show up that well due to me uploading it on an odd format.
Gives the general idea. Regards, John.

[petertheorgan]

I have just made up a "polo mint" dropper for the G E C that I am restoring , make sure that there is a strong physical connection to the dropper segments before soldering as the terminals may get hot enough to melt solder.

Photo below

Peter

[Heatercathodeshort]

Such a neat job Peter. Have you been attending crochet evening classes?

Seriously Peter a very neat job and those droppers never fail. They are indestructible. That GEC looks a cracker!
Mains droppers can be made up for any receiver with these RS 'power sections' as they were known in the catalogue. Fortunately there are still a lot of them around for us to play with.
Regards, John.

[wd40addict]

Hi John,

On your video description you say the misaligned ion trap magnet caused the tube to become slightly damaged. What happened?

Regards,

Paul

[Heatercathodeshort]

Ion trap magnets that are very slightly off adjustment can cause the microscopic hole in the grid assembly to become slightly oval due to electron stream erosion. The result of this is what is called astigmatism, the ability to focus the beam vertically or horizontally but not both together. It can also cause a random stain similar to an ion burn but an irregular shape. Ion burns tend to be 2 to 3 inches in diameter and form a perfect circle at the centre of the tube due to being influenced a lot less by the magnetic field of the deflection coils. Maintaining the maximum permissible EHT will reduce the effect due to the higher beam velocity punching through the damaged screen phosphor.
I must add that it takes years of use for these faults to become apparant to the viewer.
Regards, John.

[wd40addict]

John, thank you for the explanation! I've seen service manuals refer to tube damage if it's misaligned, but they never say what the damage is.

Regards,

Paul

[Heatercathodeshort]

I would add that ion trap magnets must at all time be adjusted for maximum brightness. They must not be used to centre the picture, remove corner cutting or compensate for poor focus.
Some non ion trap tubes such as the straight gun aluminised GEC types [aluminising replaces the need for an ion trap] use a small magnet that looks similar to an ion trap, to remove corner cutting but as I have mentioned these tubes were not fitted with a gun that required a trap. These were purely correction magnets. J.

[FERNSEH]

I'm working on a BV20C for a forum member. Having got it going I decided to bring down from upstairs my LV30C for comparison.

It hasn't been switched on for years, I must confess was not a great fan of these small Pye TVs although since working on the BV20 I changed my opinions about these sets. They are actually rather good little sets.

Anyway, The LV30C did not need any work doing to it, the picture is really good, the CRT is the ion trap Mullard MW22-16.
One problem though, the picture is off-set slightly to the left. I had a similar problem with the BV20. In that set I introduced a degree of DC component into scan coils which solved the problem.
As do not have a circuit diagram for the LV30 I'll leave the set as it is for the time being.
The set came with a Band 3 converter fitted, it was removed when I serviced the LV30 and now I have to decide whether to refit it or not. One could say it is part of the set's history so it should be refitted.
Some pictures of the working set.

DFWB.

[Heatercathodeshort]

Yes David, the unloved PYE LV30. A great little receiver weighing in at less than most valve radio receivers. By 1950 Pye must have finally used up the million boxes of EF50's left over from WW2. This was the first receiver to employ the new Mullard 'World Series' B9A valves. The Early EF80's were fitted with square tight fitting screening cans. A bit over the top but probably worth the trouble when working at full gain in a fringe area.
The chassis still sports the Octal PL38 and PZ30 soon to be replaced with the PL81, PY82 and PY80. They were produced in massive numbers and gave very little trouble. The Lopt's still hold up today. The mains dropper with it's proximity to the back cover was the only weak point. The MW22-18 tube suffers from ion burns but nothing in life is blemish free and it's all part of the history.
Pye, Bush, Ferguson and many more makers were producing first class AC/DC receivers in the 1949/50 period. Compare these with the EMI 1807. [I cannot understand why the designers at EMI didn't go to the Radio Show, purchase a Pye B18T, pull it to bits and see how it should have been done.] I have table and console versions of the LV30 and a launch article somewhere. It really was a simple receiver and very cheap to purchase. Regards, John.

[FERNSEH]

Originally Posted by Heatercathodeshort

It really was a simple receiver and very cheap to purchase. Regards, John.

Hi John,
The LV30 shows you that it is possible to make a TV set cheaply and still not compromise performance.
I'm lucky with this set because it has the ion trap CRT, the Mullard MW22-16, the tube that went on to be the standard replacement 9" tube. It replaces the MW22-7, MW22-14 and MW22-18.
These simple sets got the industry under way and allowed many more people to acquire a TV set at a reasonable price. £30 + PT.

DFWB.