Pye B18T found, how did I do?

[Boater Sam]

Just think how much easier collecting TVs will be in a year or so time when you have a driving license and a car!
Nice catch, welcome to the mad house, enjoy the journey.

[Graham G3ZVT]

Originally Posted by Brigham

What would you use to obtain the 405-line video for the Early Television Museum modulator?

You can use a Windows PC with the "right" graphics card. This post documents my "Eureka" moment when I realised that an old technique that had effectively lain dormant for 10 years can now be achieved with a PC running Windows.

https://www.vintage-radio.net/forum/...d.php?t=130716

Please note that the recommended card is now the "ATI Radeon HD 2400 Pro"

Peter Scott had done a write up:
http://www.nostalgiatech.co.uk/Baird%20240%20lines.htm

As far as I know, only Peter and I are using this method, for vintage TVs, and we would like to see it used more widely.

[Freya]

Kat Manton was using this method back in 2006 -07 as far as I know, but this is going way off topic now.

[AC/HL]

Yes, one step at a time, first you need to breathe some life into it.

[beery]

Hi 12jslater,

Originally Posted by 12jslater

I saw this the other day at an antiques shop and asked for it to be put to one side as I was using the bus and have collected it today for £55 it is complete. How did I do on the price?

That is a good price for that set in that condition. Top price should be reserved for sets with perfect cabinets. The lacquer on Pye cabinets scratches very easily, so perfect ones are rare.
One concern is the fact that there is evidence of damp (rust on the audio output transformer etc.) which can mean problems with pots and valve sockets.
There has been mention of EF50s. These are the valves in the red aluminium cans. They are reliable in themselves, but their sockets can be a problem and the fact that the valve is permanently sealed in a can means that you cannot see if there are any serious problems with it.

Pye construction is rather messy using a birds nest approach to component placement. This actually improves the stability of the RF stages, but makes repair a bit of a pain.
Make sure you take lots of close up photos of the underside before you begin replacing components.

Be aware that working on old TV sets of this age can be dangerous. The metal chassis is connected to one side of the mains, so an isolation transformer should be used when testing out of the cabinet. Do ask for any advice you might need there.

All that said, these are very reliable sets. Once all the tubular wax capacitors have been replaced and all the other faults are ironed out, they turn into great little sets. The B18T/LV20 sets produce an extremely linear raster (picture geometry is good) and they just keep working.

Overall a great find and a great introduction to 1940's televisions.

Cheers
Andy

[12jslater]

Something is missing as there is a clamp which should hold a capacitor??

[HamishBoxer]

Yes I think a capacitor is missing or been fitted elsewhere.

[Refugee]

Has it not been removed as faulty and been replaced with what can be seen top left.
It is a surely sign of an engineer who did not bother to shoe horn the new one into the original position.

[Boom]

Originally Posted by beery

There has been mention of EF50s. These are the valves in the red aluminium cans. They are reliable in themselves, but their sockets can be a problem and the fact that the valve is permanently sealed in a can means that you cannot see if there are any serious problems with it.

I think that asking an EF50 to perform as a frame output valve was expecting a bit much.

[12jslater]

UPDATE - The set has been seriously messed with and not in a good way, the soldering jobs are loose and messy and some of the new caps have a date of 55. I can only tell they have been replaced due to the date where as in other places it is original components but resoldered, this is going take longer than i thought.

And the missing capacitor has me wondering if that's the only thing that is missing.

[mark pirate]

The best approach is to go through the chassis with the circuit diagram to hand, marking off with a highlighter as you go.
Return any altered wiring/components to the original spec.

I have the service info should you need it.

Mark

[Graham G3ZVT]

Hi Jake,
As mentioned before, the capacitor that occupied that clip is probably not missing, it is more likely to have been replaced, in a different orientation.
Remember, that the engineer working on it in the 50s or early 60s, would not have had the reverence that we would have now to preserve originality, and if (say) he was replacing a tagged electrolytic in the clip, with a component with axial leads that was a different diameter for the clip, it may have made perfect sense to find a new place for it, as one end is probably going to chassis there would be plenty of options for that lead.

Also, think about the fact that all the glassware is intact (bar one valve I think you said). Is it likely that the chassis has been raided for multiple spare parts, yet the valves were left in place?

What I would do now is this. Take some good pictures at the highest resolution that your camera can manage, particularly of the underside of the chassis and upload them to a Flickr album or something equivalent.
Then we will be in a better position to advice you how to proceed.

Unfortunately, the vBulletin image handling here does not support the high resolution needed.

[Refugee]

As I posted message #28 the old component will have been chopped out to remove a short.
The new component has been soldered into a position where access to the connections is easier for soldering.
Clip mounted parts would have been installed before pre-ssembled tag strips during manufacture.
Whom in this world remove a tag strip while on a time limited service call to change a component?
It is too easy to remove valves. They would be the first components to go if a set is being stripped for spares.

[12jslater]

That had crossed my mind but I think the television has had an attempted repair by somebody with little electrical experience as there is very very very bad soldering on components (great big splodges of solder but very loose) and there is no extra cap that could have replaced the missing one, does anybody have the value of it as this would be of great help as I have seen several images of the chassis and can see where it should be connected.

[Graham G3ZVT]

Have you seen the images in this thread

https://www.vintage-radio.net/forum/...ad.php?t=31528

They should provide you with a better baseline than the layout diagram on the service sheet.

It is important that you make an equally good photographic record of how your set is now, before you make any changes.


I am not saying you are necessarily wrong about a missing component, but be aware that even before any repairman touched them, sets can evolve in small ways during a production run, and component placement or type of component, can change between specimens of the same chassis. Also component values were sometimes changed and sometimes a component is deleted completely. (although unlikely with your big capacitor).

[mark pirate]

Here are some photos of my unrestored set, hope this helps.

Mark

[Freya]

Looks like that might have been twiddled Mark. Good and sweaty though.

[Heatercathodeshort]

Don't worry about using the non metalized PL38 in place of the PL38M. The screening was to reduce the level of line timebase radiation causing interference on nearby radio receivers especially tuned to 1500m Long Wave.
The line output transformer is enclosed in a screening can for the same reason. It does not matter today as you are unlikely to find a domestic radio receiver working on LW in your immediate locality. J.

[12jslater]

I have already ordered a replacement valve that should be here for the end of the week and the capacitors are on order and only 2 resistors to replace on this set!

[Jonster]

Only two resistors? How do you know that they need changing? Good luck with the restoration they are a fairly simple set.