UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Restoration of a 1937 first generation pre-war television (HMV 900)

beery · 14th Oct 2020, 5:04 pm

Hi Catkins,
That's great work on the PSU.
How were you able to get to the point of being able to polish the chassis? Wast the rust only a thin film without any pitting?

The open circuited EHT transformer was no great loss as I suspect that if it had been intact then it would have only lasted a few hours before it started to break down anyway.

Some data on GPO heat coils:-

Heat Coil Green 5.5 ohm, trip in 60 seconds at 0.5A
Heat Coil Brown 0.7 ohm, trip in 60 seconds at 1.5A
Heat Coil Violet 8.2 ohms, trip in 120 seconds at 0.38A
Heat Coil White 20 ohms, trip in 30 seconds at 0.3A
Heat Coil Yellow 0.55 ohms, trip in 60 seconds at 2.0A

Cheers
Andy

14th Oct 2020, 5:04 pm	#44
beery Heptode Join Date: Jun 2006 Location: Ware, Hertfordshire, UK. Posts: 988	Re: Restoration of a 1937 first generation pre-war television (HMV 900) Hi Catkins, That's great work on the PSU. How were you able to get to the point of being able to polish the chassis? Wast the rust only a thin film without any pitting? The open circuited EHT transformer was no great loss as I suspect that if it had been intact then it would have only lasted a few hours before it started to break down anyway. Some data on GPO heat coils:- Heat Coil Green 5.5 ohm, trip in 60 seconds at 0.5A Heat Coil Brown 0.7 ohm, trip in 60 seconds at 1.5A Heat Coil Violet 8.2 ohms, trip in 120 seconds at 0.38A Heat Coil White 20 ohms, trip in 30 seconds at 0.3A Heat Coil Yellow 0.55 ohms, trip in 60 seconds at 2.0A Cheers Andy __________________ www.youtube.com/user/andyvalve100