hughes@math.Berkeley.EDU (Eric Hughes) (06/17/89)
I have a pair of related problems I would like to get some advice on. Both have to do with getting rid of various whines and buzzes induced by various oscillations in my computer equipment. The first is the flyback transformer in my CRT. Occasionally it whines pretty loudly, but a good whack on the side of the case makes it go away. Honest. The other is an EMI/RFI filter and surge protector which buzzes. I've taken the case off and it looks like the wire wound torroids are doing the buzzing. Sometimes it is very loud, other times not. What I would like to find is some goop to spray on the components to absorb and dissipate the vibration. I would imagine that two different products would be needed for the different frequencies involved. The surge protector is glued together and some liquid seems to be the only way to get in contact with the torroid. I have not opened up the case of my CRT to see how the flyback is mounted. Questions: Is this approach feasible and safe? Are there products specifically designed for this, or will some common material suffice? Any and all help appreciated. Eric Hughes hughes@math.berkeley.edu ucbvax!math!hughes
sparks@corpane.UUCP (John Sparks) (06/22/89)
In article <25538@agate.BERKELEY.EDU> hughes@math.Berkeley.EDU (Eric Hughes) writes: >The first is the flyback transformer in my CRT. Occasionally it >whines pretty loudly, but a good whack on the side of the case makes >it go away. Honest. This one seems to make the usenet rounds about once every 2 months or so. :-) The high frequency noise is 15Khz as the flyback works the horizontal scanning on the CRT. It is at a potential of 25KV. There is a substance called "Corona Dope" available as a paint or spray that is a very good insulator. It is used to repair leaking high voltage leads from the flyback to the CRT. You might try to put some of this on the Flyback and its core to stop the vibrations (noise). Just make sure it is something with a high insulation value like corona dope. -- John Sparks | {rutgers|uunet}!ukma!corpane!sparks | D.I.S.K. 24hrs 1200bps ||||||||||||||| sparks@corpane.UUCP | 502/968-5401 thru -5406 I'm the person your mother warned you about.
barry@hprmokg.HP.COM (Barry Fowler) (06/22/89)
Try RTV (Silicone sealant). Many TV manufacturers use it in the High Voltage circuits and, in general, to secure components. Make sure it is cured before you fire it up. "Corona dope" can also be used. It can be purchased at most electronic supply stores that specialize in TV components.
mmm@cup.portal.com (Mark Robert Thorson) (07/22/89)
My dad used to have a TV repair business in Palo Alto. He once was called to fix a set that was making a high-pitched whine. Even back then, my dad's high-frequency hearing wasn't too good, so he couldn't hear the noise the lady was complaining about. He took off the back of the set and found that there was a Coke bottle back there. He figured the noise was coming from the high voltage rectifier section (this was 30 years ago, before TV's had silicon diodes), so he shoved the Coke bottle in among the tubes there. The lady said that fixed the problem! I would guess that your problem is a bit similar. You might see if you can shove one or more toothpicks between the secondary of the flyback and the flyback's core. The toroids are probably mounted horizontally with a bolt through the center, so maybe you can tighten the bolt (or shove in more tooth picks). You say the toroids are in your EMI filter and surge suppressor? Then they shouldn't be buzzing. You'd have to have a lot of EMI to make one of those toroids flinch. Are you sure you aren't looking at your DC power supply? Lots of switching power supplies produce irritating buzzes.