On 07/05/2016 13:21, Jeroni Paul wrote:
N_Cook wrote:
I "replaced" the duff tube with 3 neons in series on the ps, and the
display and backlighting and DVD play works fine. So looks like the
unmonitored side needed a load also to bring the monitoring into valid
envelope. I have to admit its not obvious which area of the screen is
lacking light, needs wrapping up properly and a normal viewing position
perhaps. Would there be 2 long tubes top and bottom and 2 short along
the sides or 2 short each along top and bottom, I've not ventured fully
inside.
The neons run at 24 deg C over ambient, so perhaps 5 or 6 would be
better if more than a temporary fudge.

I have been looking for a practical/cheap solution for the same problem on a DELL 1707FPt computer display. It has four backlight tubes two at the top and two at the bottom. One of them was cracked and very darkened inside, the rest were fine. Problem is the inverter is not happy without a load on that output, runs for one second and shuts down. I tried three 3W resistors in series adding 120K and it works fine, yet the resistors get quite hot. The missing tube is barely noticeable, it just causes the top 1/3 of the srceen to be slightly darker but goes mostly unnoticed. I would be happy to make it work with three tubes, installing the resistors permanently is one solution but I wondered if the inverter could be modified somehow to disable or ignore that output. The inverter uses a transformer for each pair of tubes so not sure if there is anything that can be done.


This TV was running perfectly happily with 6 neons in series without any
droppers, replacing the failed tube for loading purposes, for 3 hours as
a try out of whether it was possible