britain4 wrote on 2018-06-21, 19:54:I’ve got 9 Compaq CRT screens from a job lot in my shed at the moment and I have to get rid of some as I don’t have the space! […]
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I’ve got 9 Compaq CRT screens from a job lot in my shed at the moment and I have to get rid of some as I don’t have the space!
A few of them when first turned on made a little “crack” sound from inside the screen along with the picture flickering as it made the sound
The frequency of this varies but on the worst one it did it about every 5-10 seconds at first before getting less and less frequent the longer the monitor was on. Is this something that can happen after a CRT’s been in (slightly damp) storage for a long time (probably the best part of 15 years) that’ll stop happening as they get some use or is it a sign they’re knackered?
I don’t want to start selling them only to find they’re crackling and dying for the new owner a week later but at the same time I don’t have time to thoroughly check all 9 of them for hours on end!
Funny. Last year I trash picked a 17" that had been sitting in the rain for some days. It was surprisingly clean inside and looked very unused. The former owner said it used to work and sat ~15 years before they put it onto the trash pile. I hadn't high hopes for it, but it worked after letting it dry for a few days. However, it made distinct snapping sounds like those of a high voltage DC spark flashing over, combined with a jitter of the picture. At first, it did that every one or two seconds or so, and after a minute of on time the frequency already decreased significantly. A few minutes it decreased to about 2 snaps a minute and after two hours of playing Doom the snapping was gone for good until this day. As I didn't see any visible sparks in the dark I just thought "ok, maybe there was water in the flyback".
However, last week I got donated another one with only the degauss PTC broken. I fixed that, and when turning this one on it showed exactly the same "snapping" symptoms as the one last year. This monitor was also stored in working condition ~15 years ago, but this time in a dry place. I had this thing running for like 60 minutes in total and the snapping frequency is already down to around one per 15 minutes. That doesn't make it easy to locate the source.
This behaviour can't be a coincidence. It has to be related to these things having been stored unused for a decade. I suspect something is "self-healing" when you turn these back on. I wonder if there is a hidden spark gap somewhere which would explain why I am not able to see these sparks in the dark.