dseah@wpi.wpi.edu (David I Seah) (06/21/89)
A friend of mine has taken to beating his Apple IIGS RGB monitor. After about
an hour of use, something inside it starts this incredibly annoying
high-pitched whine. Whacking the monitor will fix it for about ten minutes,
but the noise soon returns. After a certain point, nothing will stop the
noise, and my friend has to poweroff for at least an hour.
Any ideas what is causing this?
--
David I. Seah | dseah@wpi.wpi.edu | Twinkie & Banana Club - MA
| dseah@wpi.bitnet | "Amazing stuff, plastic!"JWANKERL@UTCVM.BITNET ("Josef W. Wankerl") (06/21/89)
On Tue, 20 Jun 89 20:05:27 GMT David I Seah said: >A friend of mine has taken to beating his Apple IIGS RGB monitor. After about >an hour of use, something inside it starts this incredibly annoying >high-pitched whine. Whacking the monitor will fix it for about ten minutes, >but the noise soon returns. After a certain point, nothing will stop the >noise, and my friend has to poweroff for at least an hour. > >Any ideas what is causing this? > >-- >David I. Seah | dseah@wpi.wpi.edu | Twinkie & Banana Club - MA > | dseah@wpi.bitnet | "Amazing stuff, plastic!" I had the exact same problem with my monitor a while back. It's the fly back transformer (or so the guy said when I took it in to be fixed). They replaced it for free (it was still under warranty) for me, so I was happy. Before I took it in it was *extremely* annoying to listen to... to the fact that I didn't want to use my computer, even. This sounds like something might be flaky with the RGB architecture if things like this go wrong a lot, but maybe it's just a chance type thing... -Gonzo /**********************************************************************\ |* Joe "Gonzo" Wankerl |*| The views expressed here are *| |* BITNET => JWANKERL@UTCVM |*| not necessarily yours... *| |* |*| ...but they should be. *| \**********************************************************************/
SEWALL@UCONNVM.BITNET (Murph Sewall) (06/22/89)
>an hour of use, something inside it starts this incredibly annoying >high-pitched whine. Whacking the monitor will fix it for about ten minutes, >but the noise soon returns. > >Any ideas what is causing this? I had a TV which did that once. By and by, the power supply melted itself into a glob and shorted out entirely. Dying transformers can complain audibly. If that's the cause, eventual labor costs will be much lower if some expensive per hour tech doesn't have to spend a lot of time *literally* scrapping hardened transformer innards out of the monitor case. Murph Sewall Vaporware? ---> [Gary Larson returns 1/1/90] Prof. of Marketing Sewall@UConnVM.BITNET Business School sewall%uconnvm.bitnet@mitvma.mit.edu [INTERNET] U of Connecticut {psuvax1 or mcvax }!UCONNVM.BITNET!SEWALL [UUCP] (203) 486-5246 [FAX] (203) 486-2489 [PHONE] 41 49N 72 15W [ICBM] -+- I don't speak for my employer, though I frequently wish that I could (subject to change without notice; void where prohibited)
myers@hpfcdj.HP.COM (Bob Myers) (06/22/89)
>A friend of mine has taken to beating his Apple IIGS RGB monitor. After about >an hour of use, something inside it starts this incredibly annoying >high-pitched whine. Whacking the monitor will fix it for about ten minutes, >but the noise soon returns. After a certain point, nothing will stop the >noise, and my friend has to poweroff for at least an hour. >Any ideas what is causing this? This is almost undoubtedly one of the magnetics in the horizontal deflection circuit - probably the flyback transformer - vibrating at the horizontal sweep frequency. This sort of thing happens quite often, and usually flybacks and the like are varnished, potted in epoxy, or otherwise secured to prevent it (it's really the ferrite core vibrating in its mounting, or the two halves of the core vibrating, etc.). The horizontal linearity coil is also a likely culprit. You can confirm the problem by touching the flyback with an *insulated* rod (a plastic rod is ideal, or touch it with the eraser end of a wooden pencil), and listening for a change in the sound - or maybe even a cessation of the noise. (NOTE: The insides of monitors are dangerous places to be - there are some particularly nasty voltages to be found here, esp. around the deflection circuits and flyback. DO NOT do this unless you're confident you know what you're doing!!!!) If you can confirm which part is "singing", try fastening it down a little better by using some RTV adhesive or HV "corona dope". (Whatever you use should be suitable for high voltage and moderately high-temperature environments. I've used RTV with some success for quite a while.) Pay particular attention to the core mounting and any gaps between core pieces. Hope this helps! Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not Ft. Collins, Colorado | those of my employer or any other myers%hpfcla@hplabs.hp.com | sentient life-form on this planet.
bird@ihlpf.ATT.COM (Walters) (06/22/89)
From article <8906211109.aa02636@SMOKE.BRL.MIL>, by JWANKERL@UTCVM.BITNET ("Josef W. Wankerl"):
> I had the exact same problem with my monitor a while back. It's the
> fly back transformer. (text deleted)
> This sounds like something might be flaky with the RGB
> architecture if things like this go wrong a lot, but maybe it's just
> a chance type thing...
The flyback circuitry is where much of the power in any vdt is
consumed and since power translates to heat &/or wear, that is
where such things tend to break.
--
Joe Walters att!ihlpf!bird
IHP 1F-240 (312) 713-5356sb@pro-generic.cts.com (Stephen Brown) (06/22/89)
Network Comment: to #2587 by pnet01!crash!purdue.edu!mailrus!ulowell!m2c!wpi!dseah For about the first 6 months, my monitor did exactly the same thing. It would be on for a while and all would be well. Then after an hour it would whine annoyingly until (a) it was given a few good whacks, or (b) until it felt better, or (c) until the relative positions of the planets pleased it again. Then all would be well again. I WAS going to take it in to my local (?) freindly (?) Apple dealer, but the problem went away by itself. I suspect that it was either the PC-board, the flyback transformer core, or the horizontal output transistor that was vibrating in response to the 15,750hz horizontal-oscillator signal which causes the electron beam to do a horizontal dance across the picture tube screen. In TV sets, the actual offending vibrating piece may be difficult to pinpoint, but its in there somewhere. I don't know whether the heat (and thermal expansion) causes something to be the right shape/size to resonate, but it would make sense. Unfortunately, hard to trace, and the act of moving the monitor might be enough to cure it.... I don't know. Stephen Brown ProLINE: crash!pnet01!pro-generic!sb@nosc.mil
lauch@cpsc.ucalgary.ca (Christopher Lau) (06/24/89)
I don't think it's a design flaw in the monitor.. a lot of monitors regardless of brand do this.. I've got a Zenith ZVM-122 Amber monitor, and it occasionally produces a high pitched whine which can be cured by smartly whacking the monitor on the right side.. I've also experience the same symptoms with my DataTrain DC600 on my PC compatible.. I think the whine is related to resonance in the ferrite core of the flyback.. and is harmless but annoying Chris
JWANKERL@UTCVM.BITNET ("Josef W. Wankerl") (06/26/89)
On Fri, 23 Jun 89 17:04:43 GMT Christopher Lau said: >I don't think it's a design flaw in the monitor.. a lot of monitors >regardless of brand do this... (Text omitted) > >Chris Well they shouldn't do that. It's a pain to listen to one. Since it doesn't work the way I want it to, I think it is a flaw. I want my monitor to be nice and quiet, thank you. -Gonzo /**********************************************************************\ |* Joe "Gonzo" Wankerl |*| The views expressed here are *| |* BITNET => JWANKERL@UTCVM |*| not necessarily yours... *| |* |*| ...but they should be. *| \**********************************************************************/
barak@lakesys.UUCP (Mark Litscher) (06/27/89)
As far as I have ever noticed all monitors and TVs do this. I can walk past a room and tell if a TV is on or not. As long as I am not reminded of the wine, it doesnt really bug me, but when people talk about it alot it get's to be rather annoying. Most of the time I have discussed it with anyone else we decide it's the magnets resonating to the vertical scan rate. Later... ------------------------------------------------------------------------------ | Mark Litscher | "Ahead warp zillion!" | | barak@lakesys.COM | "Ack phbbbt!" | ------------------------------------------------------------------------------