UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Pye StudioCOLOUR (K35 chassis) No picture / sound

harvestgold · 19th Jan 2022, 4:43 pm

Thanks Glyn - much appreciated!

Firstly, I checked the brightness / contrast voltages on the decoder and they are normal enough - brightness 0.5 - 3.1v on pin 18 & contrast 2.3-3.2 on pin 19.

Then I looked at TS535, and the voltages are a bit off here:
Again according to the diagram, I should have 12.3v on the base, but have 16.9v.
At pins 5 & 9 on the decoder connector, (which goes to pin 8 on the TDA3560) I should have 1.1v but have 5.4v.

I've checked the resistors surrounding TS535 (R535, R534, R529 & R540) all are ok.

I wonder if the overly high voltages are a symptom or a cause of the problem?

Neil.

19th Jan 2022, 4:43 pm	#27
harvestgold Hexode Join Date: Jul 2005 Location: Worcestershire, UK. Posts: 282	Re: Pye StudioCOLOUR (K35 chassis) No picture / sound Thanks Glyn - much appreciated! Firstly, I checked the brightness / contrast voltages on the decoder and they are normal enough - brightness 0.5 - 3.1v on pin 18 & contrast 2.3-3.2 on pin 19. Then I looked at TS535, and the voltages are a bit off here: Again according to the diagram, I should have 12.3v on the base, but have 16.9v. At pins 5 & 9 on the decoder connector, (which goes to pin 8 on the TDA3560) I should have 1.1v but have 5.4v. I've checked the resistors surrounding TS535 (R535, R534, R529 & R540) all are ok. I wonder if the overly high voltages are a symptom or a cause of the problem? Neil.