UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Pye CT205 various faults

Mikey405 · 19th May 2007, 3:05 pm

Hi Taz.

All you need to do is disconnect the 2 little leads (Red and Blue) from the decoder to the CDA panel to rule out the decoder.

I think a scope would be an invaluable aid to sorting out this problem Taz. I can send you a disc with a cross-hatch pattern on if you would like, and then you can get the scope on the CDA panel and start comparing the blue with the other signals. I'm sure you'd be able to find the fault pretty quickly then. If you get stuck, I can always send you another CDA panel, but it may have a worse fault than this one, or you are welcome to bring the set up to Solihull, but it is a bit of a journey for you down in London.

It's interesting that the effect is present to a slight degree on the Green too. The G-Y being generated partly by the B-Y of course. This may point you in the direction of checking on the low-voltage side of the CDA panel too. Perhaps C359, R370, R373 or R364? Maybe even VT31 itself...

Thanks Taz.

Kind regards.

From Mike.
PS. I have dozens of NOS PL509s if you want one.
PPS. Do you have a picture of the red output on its own?

19th May 2007, 3:05 pm	#21
Mikey405 Octode Join Date: Jul 2006 Location: Solihull, West Midlands and Beaford, Devon Posts: 1,626	Re: Pye CT205 - a partial success story! Hi Taz. All you need to do is disconnect the 2 little leads (Red and Blue) from the decoder to the CDA panel to rule out the decoder. I think a scope would be an invaluable aid to sorting out this problem Taz. I can send you a disc with a cross-hatch pattern on if you would like, and then you can get the scope on the CDA panel and start comparing the blue with the other signals. I'm sure you'd be able to find the fault pretty quickly then. If you get stuck, I can always send you another CDA panel, but it may have a worse fault than this one, or you are welcome to bring the set up to Solihull, but it is a bit of a journey for you down in London. It's interesting that the effect is present to a slight degree on the Green too. The G-Y being generated partly by the B-Y of course. This may point you in the direction of checking on the low-voltage side of the CDA panel too. Perhaps C359, R370, R373 or R364? Maybe even VT31 itself... Thanks Taz. Kind regards. From Mike. PS. I have dozens of NOS PL509s if you want one. PPS. Do you have a picture of the red output on its own? __________________ G7TRF Last edited by Mikey405; 19th May 2007 at 3:27 pm.