Pye CTM4 "Continental"

[Terry]

Trevor, have you thought of impregnating the transformer in something suitable or even just trickling it into coils?

By filling any air spaces it would both constrict the wire and provide sound deadening.

An alternative, suggested by Bush, I think, when a customer complained about the volume of the line whistle was to hang heavy curtains behind the set!

[ppppenguin]

I thought Trevor had used a jellypot transformer, so not possible to impregnate any further.

[Murphyv310]

Hi.
Yes I've used Jellypots in two Bush TV22 but not in the Pye V4. Jellypots are like a Rolls Royce for being quiet but the Ferguson one frightens the life out of anything that comes close.
I'll pop up a photo of it later.

[Murphyv310]

As promised.

   

[Geordie McBoyne]

It's time to do my line output transformer substitution in the Pye CTM4.  it's almost five years ago when I fitted an ersatz line output transformer in another Pye TV set, a CTL58F.  The transformer chosen for the task was a multi-purpose transformer which was donated by UKVRRR member Wilfrid (wiwior). The transformer was designed for use in an 819 line set, however, it has been discovered that the same transformer work on the 405 and 625 line standards.
This is the transformer I'm going to fit in the CTM4.
The link to the UKVRRR topic about the Pye CTL58 restoration:                                                https://www.vintage-radio.net/forum/show...p?t=100522

Geordie McBoyne.

[Geordie McBoyne]

Wired in the substitute transformer this evening. Using the Rank-Bush-Murphy EHT meter to monitor the results I find that just under 11KV is available at the cathode of the EY86 rectifier, just about right figure for the 14" CRT.
It's likely a higher EHT voltage will be possible when the CRT is connected.
Tomorrow the chassis will be refitted in the cabinet so then we'll find out if the French 819 line transformer will work properly in the 405 line CTM4.
At least this evenings experiment proves that the original line output transformer is faulty.

Geordie McBoyne.

[Geordie McBoyne]

This morning I tried out another line output transformer in the CTM4. This one is of unknown origin, most likely it was taken out of an early fifties set.
Can anyone identify it?

Anyway, it's of no use in the CTM4, the EHT voltage is only 7KV, so it's most likely it was once fitted in a 12 inch CRT receiver. The EHT rectifier is an EY51.

According to the VT4 service manual the EHT should be 14KV.

Geordie McBoyne.

[Murphyv310]

Hi.
Here are some pictures of the V4,  its chassis is quite rusty but the pictures are stunning,  I've no intention of cleaning up the chassis as this set has an interesting history and the rust depicts it's early life and the conditions it was used in.
   
   
   

[Geordie McBoyne]

My ViewMaster TV was pretty rusty when I found it.

Geordie McBoyne.

[Geordie McBoyne]

Yesterday evening the chassis was reinstalled into the cabinet.
The scan coils refitted on the tube neck, the ion trap positioned in line with CRT base pin 3, the link between CRT heater pins 1 and 12 removed.
The set is ready for testing.
The attachment shows the results. Even with only 10KV the picture is quite bright. The height control has no effect on the picture, turns out the coupling capacitor between the frame oscillator and the grid of the PL82 output valve needs rewiring so that the height control is in series with the capacitor. No frame sync will almost certainly be the miniature selenium interlace diodes having gone high forward resistance.
No line sync because the reference pulses to the flywheel discriminator are absent.
Now we know the set is a viable restoration proposition I might consider having the original line output transformer rewound.

Geordie McBoyne.