16 Oct
2013
16 Oct
'13
10:40 a.m.
On Wed, 16 Oct 2013, Tony Duell wrote:
Sure. I've bene none ot cautiously weak the sub-brightness and A1
('screen') presets in some 'blank screen' monitors to see if I can coax
any light out of the CRT. But I would advie against twiddling prests
unless you know what they do.
An old TV engineer's trick was to shrrt the control grid of the CRT to
its cathode. If the fault is in the video stages, the CRT is being biased
beyond cut-off, then this will get a bright white raster. Again, do it
with care, some video amplifiers don't like it too much.
The monitor circuit is pretty conventional,
fromwhat I remember, but I
suspect that's not a lot of ohelp to you. I cna tell you how I'd
troubleshoot it :
0.5) Turn up the brightness.
In this, and many other cases, that is ALL that is needed.
But, in many cases people will be horribly offended by that suggestion.
But, in the case of an actual fault, being able to see whether the screen
lights up and/or shows a raster and/or retrace is a significant diagnostic
step. 1) Take off the case. Power up
Although not relevant here, check the other controls.
When I was in college, there was a little Sony monitor (AC/DC, with tuner
AND video inputs) from a Sony AV series video recorder that was discarded.
I found that there was a double throw switch that was in between its two
positions.