mkent@violet.berkeley.edu (08/05/86)
My amiga monitor has started producing a high-pitched sound after it warms
up. This is extremely annoying, to say the least. I've discovered that
the old-style TV remedy (hitting the cabinet a sharp blow to the side!)
works briefly, but the shriek returns. Has anyone had a similar problem
with a monitor? Suggestions (non- Rube Goldberg) for its correction?
ralph@mit-atrp.UUCP (Amiga-Man) (08/07/86)
In article <1055@jade.BERKELEY.EDU> mkent@violet.berkeley.edu () writes: >My amiga monitor has started producing a high-pitched sound after it warms >up. This is extremely annoying, to say the least. I've discovered that >the old-style TV remedy (hitting the cabinet a sharp blow to the side!) >works briefly, but the shriek returns. Has anyone had a similar problem >with a monitor? Suggestions (non- Rube Goldberg) for its correction? > Such noises may be due to the stepup tranformer which creates the high voltages for the front of the screen. If they aren't mounted correctly or aren't wound right you get noise. There's also the deflection coils which might make such a noise. You hear a high pitched whine cause the horizontal sweep freq. is around 15Khz, just at the top of human hearing range. I really wouldn't recommend hitting the thing. It will just loosen up circuitry inside, especially the picture tube guts, making failure happen sooner. Perhaps you could get it serviced, or if you know what you are doing (LOOK OUT for stored high voltages, even when it's OFF!) you could investigate the noise source.
mykes@3comvax.UUCP (Mike Schwartz) (08/07/86)
In article <1055@jade.BERKELEY.EDU> mkent@violet.berkeley.edu () writes: >My amiga monitor has started producing a high-pitched sound after it warms >up. This is extremely annoying, to say the least. I've discovered that >the old-style TV remedy (hitting the cabinet a sharp blow to the side!) >works briefly, but the shriek returns. Has anyone had a similar problem >with a monitor? Suggestions (non- Rube Goldberg) for its correction? > Get a bigger hammer? (sorry, couldn't resist)
rick@mips.UUCP (08/12/86)
> My amiga monitor has started producing a high-pitched sound after it warms > up. This is extremely annoying, to say the least. I've discovered that > the old-style TV remedy (hitting the cabinet a sharp blow to the side!) > works briefly, but the shriek returns. Has anyone had a similar problem > with a monitor? Suggestions (non- Rube Goldberg) for its correction? > As a previous poster replied, the most likely cause of the high pitched squeal you hear is from the "high-voltage-step-up" transformer, also known as a flyback transformer (due to the way it generates a high voltage using the horizontal oscillator waveform). This noise is also common to television sets. The transformer is easily found by following the fat red wire from the side of the picture tube of the monitor. There should be a funny looking transformer near the end of the wire, kinda like a snail that's been impaled by a square loop of metal. The "loop" is the "core" of the transformer, and it is likely what you hear making noises. there are normally a couple of small bolts holding the thin laminations of this core together, and with age, they can loosen up. Normally the best way (as the repairmen fix them) is to put a bit of epoxy over the windings in a couple of places, and secure the core to it's mounts again. Tightening the little bolts usually broke them off, so the epoxy method works best overall. Some caveats, however: 1) the voltage on the red wire can exceed 18,000 volts (yes, eighteen thousand), so it's nothing to be messed with. 2) there can be a helthy voltage still on the lead for up to 6 hours after you turn the unit off (the tube is used as a capacitor), so a few minutes wait is NOT sufficient. 3) your warranty, if still in effect will certainly be voided if you open the case of the monitor. 4) it could, though not likely, be the deflection coils mounted on the back of the tube. Any competent tv serviceman could take care of the noise for you in less than 1/2 hour, if it indeed is the flyback transformer (99 out of 100 times this is the case, at least in television sets), so it may be best to run the unit down to the local computer repair place (if they have any video guys around) or a tv repair place. If you don't like these solutions, you could always get a nice little amplifier, hook it up to the Amiga's stereo outputs, and use headphones like my son does....(for programs without sound output, he listens to a local rock station..) good luck-- -- --Rick Frazier-- DISCLAIMER: The above is individual opinion (the result of my imperfect recall of facts, real or imagined) in no way representing anyone else. UUCP: {decvax,ucbvax,ihnp4}!decwrl!mips!rick DDD: 408-720-1700 x278