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murphyv310 · 14th Sep 2011, 9:34 pm

Hi Colin.
In addition to HKS's advice, there are two things that come to mind, 1, the Cathode of the CRT is O/C and no amount of shorting grids to cathodes will help.
2, You now need to ascertain the CRT has emission, If you don't have an EHT meter you can insert a microamp meter in series with the cathode, upping the brightness should increase the cathode current, if this increases then you should have a raster and adjusting the ION trap should result in said raster.
No increase in cathode current on upping the brightness would suggest an O/C cathode or very low CRT. shorting grid to cathode of the tube should show some current on the meter but nothing denotes a duff tube.

14th Sep 2011, 9:34 pm	#124
murphyv310 Dekatron Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,422	Re: Restorers dream part 2 the chassis. Hi Colin. In addition to HKS's advice, there are two things that come to mind, 1, the Cathode of the CRT is O/C and no amount of shorting grids to cathodes will help. 2, You now need to ascertain the CRT has emission, If you don't have an EHT meter you can insert a microamp meter in series with the cathode, upping the brightness should increase the cathode current, if this increases then you should have a raster and adjusting the ION trap should result in said raster. No increase in cathode current on upping the brightness would suggest an O/C cathode or very low CRT. shorting grid to cathode of the tube should show some current on the meter but nothing denotes a duff tube. __________________ Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member Last edited by murphyv310; 14th Sep 2011 at 9:45 pm. Reason: Wrong name, silly me!