To add some background to this thread, the set in question is a 20" Alba T1520, dating from 1974 and one of the few 1500s to be blessed with a wooden cabinet, as opposed to plastic. This was our family set for a few years in the mid 70s, before being replaced with a Ferguson 9000 series colour mode in 1977/8l. The Alba wobbled on it's silver legs for many years as a second set and latterly as a VDU for my Sinclair ZX81 computer. I'm sure the set went to the tip still working sometime in the 1990s. How did I ever let that happen?
Fast forward to a year or so ago and a visit to Neil in Newport who had rescued some sets from an old cellar of a shop in Bristol - correct me if I'm wrong Neil!
One of these refugees was a T1520, which Neil very kindly gave me when I told him it was a model I knew well.
The cellar storage had done the set no favours at all and any thoughts of bravely switching on were switfly curtailed after a cursory glance at the state of the capacitors. Several of the electrolytics were oozing and bulging. All were replaced, along with a couple of wirewound resistors whose legs had rusted through. I also treated the set to a NOS dropper. During this time Marc and Glenys of this parish dropped by for a visit. Marc had his tube tester with him and the previously poor reading given by the A50-120WR crt in the Alba improved markedly after a gentle clean and balance, enough for Marc to give it the thumbs up.
The first power-up of the set proved surprising, as when the line scan started the frequency sounded about spot on for 405 lines! A dim raster lacking height was obtained. Clearly the line frequency was way off. It was also noted that the initial snow visible on screen had vanished leaving a blank raster. IF trouble and a brace of dying transistors no doubt!
What EHT there was evaporated and the line whistle dwindled to something sounding not unlike the dying moments of a bluebottle trapped in a jar. My good friend Brian has VT10 the flywheel DC amp in his sights as being highly suspect. I wouldn't be surprised if all the transistors in the set turned out to be duff. I can give you a couple of voltages:VT10
Emitter 8v (should be 1v)
Collector 10.1v (should be 44v)
So that's where things currently stand, folks. There's also the question of whether damp ingress has affected the line blocking oscillator transformer (T1)
(With grateful thanks to Brian for his invaluable help)