Philips K9. - UK Vintage Radio Repair and Restoration Discussion Forum

Hampus · 4th Feb 2013, 2:43 pm

This tuning cap in my Philips K9 also went open a few years ago. I was watching the set when the picture suddenly collapsed and there was a loud and nasty high voltage flashover. I jumped out of the sofa and turned the set off. A search on google told me that this capacitor was a common fault on Philips K9 and that it could result in such horrible damage as a punctured CRT.

I took the back cover off, I felt sorry for myself and expected the worst has happened. But no damage could be seen on the CRT, and after I replaced the capacitor the TV worked perfectly again and has done so for several years now.

Always replace this capacitor! Not everyone is as lucky as I was, and a capacitor is much cheaper and easier to get than a new CRT!

Billy T · 14th Feb 2013, 4:17 am

They could sometimes run for a brief period with a very small and bright picture, during which time they were reputedly generating X-Rays.

It was a tribute to the quality of Philips Loptx and triplers that they could withstand that treatment. The caps failed open circuit, and in some cases, if the line output transistor did not succumb to the flyback peak, they could run long enough for the EHT to perforated the neck of the CRT.

I seem to recall that it was the light green tuning caps that failed, the dark green ones were very reliable but if they did fail, it was always short-circuit and no harm was done.

Cap value was 11n5 if I recall correctly.

Cheers

Billy

Mike Phelan · 14th Feb 2013, 10:28 am

I assume it's the fifth-harmonic tuning across the LOPTx?

Hampus · 16th Feb 2013, 2:56 am

This problem seems to plague more of Philips models. I have a K9.

It's about the capacitor(s) across the horizontal output transistor. Some models of K9 had two caps in parallel, some had just one cap. The total capacitance was 11.5nf anyway.

4th Feb 2013, 2:43 pm	#1
Hampus Pentode Join Date: May 2010 Location: Sandviken, Sweden Posts: 233	Philips K9. This tuning cap in my Philips K9 also went open a few years ago. I was watching the set when the picture suddenly collapsed and there was a loud and nasty high voltage flashover. I jumped out of the sofa and turned the set off. A search on google told me that this capacitor was a common fault on Philips K9 and that it could result in such horrible damage as a punctured CRT. I took the back cover off, I felt sorry for myself and expected the worst has happened. But no damage could be seen on the CRT, and after I replaced the capacitor the TV worked perfectly again and has done so for several years now. Always replace this capacitor! Not everyone is as lucky as I was, and a capacitor is much cheaper and easier to get than a new CRT!

14th Feb 2013, 4:17 am	#2
Billy T Retired Dormant Member Join Date: Feb 2008 Location: Auckland, New Zealand Posts: 631	Re: Philips K9. They could sometimes run for a brief period with a very small and bright picture, during which time they were reputedly generating X-Rays. It was a tribute to the quality of Philips Loptx and triplers that they could withstand that treatment. The caps failed open circuit, and in some cases, if the line output transistor did not succumb to the flyback peak, they could run long enough for the EHT to perforated the neck of the CRT. I seem to recall that it was the light green tuning caps that failed, the dark green ones were very reliable but if they did fail, it was always short-circuit and no harm was done. Cap value was 11n5 if I recall correctly. Cheers Billy

14th Feb 2013, 10:28 am	#3
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Re: Philips K9. I assume it's the fifth-harmonic tuning across the LOPTx? __________________ Mike.

16th Feb 2013, 2:56 am	#4
Hampus Pentode Join Date: May 2010 Location: Sandviken, Sweden Posts: 233	Re: Philips K9. This problem seems to plague more of Philips models. I have a K9. It's about the capacitor(s) across the horizontal output transistor. Some models of K9 had two caps in parallel, some had just one cap. The total capacitance was 11.5nf anyway.