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

ms660 · 31st Aug 2018, 6:36 pm

Ballooning means the picture gets magnified as the brightness is increased, eg: picture over scanned, if it's very bad the raster will disappear with the brightness turned up, it's due to insufficient EHT, the most common cause back in the day used to be the EHT rectifier loosing its umph, the beam's velocity is reduced therefore the scan coils can deflect the beam more than they would if the EHT was normal.

Lawrence.

31st Aug 2018, 6:36 pm	#21
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Help needed restoring a Murphy V310 Ballooning means the picture gets magnified as the brightness is increased, eg: picture over scanned, if it's very bad the raster will disappear with the brightness turned up, it's due to insufficient EHT, the most common cause back in the day used to be the EHT rectifier loosing its umph, the beam's velocity is reduced therefore the scan coils can deflect the beam more than they would if the EHT was normal. Lawrence. Last edited by ms660; 31st Aug 2018 at 6:41 pm.