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brianc · 9th May 2007, 7:54 pm

Hi all
I've been working on a TV62 (the one with the cracked case!) and when powered up, the tube looked a bit tired. A check on the positioning and ion trap assemblies (it's an electrostatically focused tube) improved matters a tremendous amount but it still looked rather dim. I decided to measure the volts across the tube heater. 3.62V!! I then measured the volts across the RF chassis heater chain - this calculates at 69.1V - and got 80V. Why? I decided to open the chain and measure the current. This was a little high at 312mA but this, theoretically, doesn't give 80V. As the tube heater has the right current flowing through it, can I assume that the heater is getting the correct "heating effort"? Help please.
Cheers
Brian

9th May 2007, 7:54 pm	#1
brianc Rest in Peace Join Date: Jun 2004 Location: Burghfield, Reading, Berkshire, UK, Posts: 1,055	Bush 62 Series heater chain anomalies Hi all I've been working on a TV62 (the one with the cracked case!) and when powered up, the tube looked a bit tired. A check on the positioning and ion trap assemblies (it's an electrostatically focused tube) improved matters a tremendous amount but it still looked rather dim. I decided to measure the volts across the tube heater. 3.62V!! I then measured the volts across the RF chassis heater chain - this calculates at 69.1V - and got 80V. Why? I decided to open the chain and measure the current. This was a little high at 312mA but this, theoretically, doesn't give 80V. As the tube heater has the right current flowing through it, can I assume that the heater is getting the correct "heating effort"? Help please. Cheers Brian