UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Malcolm Burrell · 24th Sep 2007, 8:49 pm

Actually, the image on the TV24 isn't bad! The previous comments regarding the centring adjustments on the bronze backing plate are correct. The screws can be tight and must be adjusted with care - if you hear the focus magnet grating on the tube neck, stop!

In my youth I ruined dozens of sets while striving for perfection! The slight displacement of the lower portion of the test card isn't the result of shorting turns in the scanning coils. It is almost certainly the result of their assembly. That was the result of mass production. Another set of coils might be an improvement but there might be distortion elsewhere. These sets were made to a budget and on the assumption that the viewer was going to watch Muffin the Mule instead of the test card!

As to definition, most of these sets should just about display the 2.5MHz bars (4th set on left) on Test Card 'C'. An exceptional receiver might faintly show the 3MHz bars (5th set on left) on a broadcast transmission. However, unless using the 'NTSC' version of the Aurora standards converter, the highest video frequencies are attenuated to remove any residue of the colour sub-carrier. A good picture resolving 2MHz is preferable to one badly resolving higher definition with 'ringing' etc.

24th Sep 2007, 8:49 pm	#6
Malcolm Burrell Retired Dormant Member Join Date: Oct 2006 Location: Romford, Essex, UK Posts: 3	Re: TV24 Help required please Actually, the image on the TV24 isn't bad! The previous comments regarding the centring adjustments on the bronze backing plate are correct. The screws can be tight and must be adjusted with care - if you hear the focus magnet grating on the tube neck, stop! In my youth I ruined dozens of sets while striving for perfection! The slight displacement of the lower portion of the test card isn't the result of shorting turns in the scanning coils. It is almost certainly the result of their assembly. That was the result of mass production. Another set of coils might be an improvement but there might be distortion elsewhere. These sets were made to a budget and on the assumption that the viewer was going to watch Muffin the Mule instead of the test card! As to definition, most of these sets should just about display the 2.5MHz bars (4th set on left) on Test Card 'C'. An exceptional receiver might faintly show the 3MHz bars (5th set on left) on a broadcast transmission. However, unless using the 'NTSC' version of the Aurora standards converter, the highest video frequencies are attenuated to remove any residue of the colour sub-carrier. A good picture resolving 2MHz is preferable to one badly resolving higher definition with 'ringing' etc.