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FERNSEH · 18th Nov 2007, 1:17 am

The Pye CTV has always had a frame timebase fault, displaying compression at the bottom of the picture. Various frame output transformers have been tried with little or no improvement. Also, there has been just sufficient vertical scan to fill the screen. I've always suspected that the fault is between frame output transformer secondary and the scanning coils. The set has a lot of RCA CTC2B DNA in it, the colour decoder is similar and so is the frame output stage. Like the CTC2B the Pye employs a vertical centering choke which is associated with the vertical shift control. A non-polarised 1000microfarad capacitor is connected between scanning coils, the centering choke and the secondary of the frame output transformer.
This capacitor has gone low capacity. I've replaced it. I'll report the results of this evenings work tomorrow.

DFWB.

18th Nov 2007, 1:17 am	#2
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Coming soon: 405 colour on my Pye CTV The Pye CTV has always had a frame timebase fault, displaying compression at the bottom of the picture. Various frame output transformers have been tried with little or no improvement. Also, there has been just sufficient vertical scan to fill the screen. I've always suspected that the fault is between frame output transformer secondary and the scanning coils. The set has a lot of RCA CTC2B DNA in it, the colour decoder is similar and so is the frame output stage. Like the CTC2B the Pye employs a vertical centering choke which is associated with the vertical shift control. A non-polarised 1000microfarad capacitor is connected between scanning coils, the centering choke and the secondary of the frame output transformer. This capacitor has gone low capacity. I've replaced it. I'll report the results of this evenings work tomorrow. DFWB.