Decca 1000 Projection TV. No EHT. - UK Vintage Radio Repair and Restoration Discussion Forum

robot797 · 22nd May 2015, 8:49 pm

I have a problem with my EHT unit. It oscillates on 960Hz, there is -33V on the grid of the EL38 and there is no high voltage.

Who here can help me in finding the problem?

Danny · 26th May 2015, 11:32 pm

Hi have you tried a new EL38. I have known these to cause this problem. Is the screen supply to the EL38 present. Next you need to see if you can draw a small spark at the EL38 anode. If yes then the ringing transformer block has problems. Also check the HT is reaching the ringing transformer primary. You can run these up on a bench supply if you have one, to make working on the unit more easy. Danny

HamishBoxer · 28th May 2015, 12:01 pm

Believe these are full of EY51's possibly suspect.

22nd May 2015, 8:49 pm	#1
robot797 Triode Join Date: Dec 2014 Location: Enschede, Overijssel, Netherlands Posts: 24	Decca 1000 Projection TV. No EHT. I have a problem with my EHT unit. It oscillates on 960Hz, there is -33V on the grid of the EL38 and there is no high voltage. Who here can help me in finding the problem?

26th May 2015, 11:32 pm	#2
Danny Heptode Join Date: Jul 2003 Location: North Walsham, Norfolk, UK. Posts: 516	Re: Decca 1000 Projection TV. No EHT. Hi have you tried a new EL38. I have known these to cause this problem. Is the screen supply to the EL38 present. Next you need to see if you can draw a small spark at the EL38 anode. If yes then the ringing transformer block has problems. Also check the HT is reaching the ringing transformer primary. You can run these up on a bench supply if you have one, to make working on the unit more easy. Danny

28th May 2015, 12:01 pm	#3
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,930	Re: Decca 1000 Projection TV. No EHT. Believe these are full of EY51's possibly suspect. __________________ G8JET BVWS Archivist and Member V.M.A.R.S