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Old 19th Jul 2011, 2:15 pm   #33
TriMan66
Pentode
 
Join Date: Jun 2009
Location: Royston
Posts: 116
Default Re: Help with a HMV TV

The previous issue with the EL36 overheating is not present anymore and the HT1 and HT2 lines are stable within a few volts of their correct values.
The current problem is that the boost volts take over an hour to rise from 450V to 650V.
This has now happened three times.
The pictures below show the TV picture with boost volts at 450V, 550V and 650V, and then the test pattern at 670V. The boost volts then remain at 670V after that. The correct value is 650V.
Pin 3 volts to the tube are a little low at 360V instead of 400V.
I thought I might try another slow baking session. The reason I haven't coated the EHT winding yet, is that I didn't want to do something permament just at the moment.
I'd like to ask people's opinion to see how to resolve this slow rising boost volts issue.

regards
Craig
Attached Thumbnails
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Name:	HMV_TV_Picture_Boost_450V.jpg
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Name:	HMV_TV_Picture_Boost_550V.jpg
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Name:	HMV_TV_Picture_Boost_650V.jpg
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ID:	54139   Click image for larger version

Name:	HMV_TV_TestPattern_Boost_650V.jpg
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ID:	54140  
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