So, my old Magnavox set is making a strange noise. Whenever a particularly bright scene comes on the set, it begins to make a high pitched "whistling" or "squealing" noise. It's different than the noise of the H.Oscillator, but I notice that whenever, say an ad, comes on and gives me a totally white screen, the picture wiggles a little from side to side.

I've had the back off the set when it was operating, and while I was adjusting the convergence, and I couldn't see any arcing or corona.

Any idea what it is? The Oscilator maybe? Perhaps some kind of arcing within the flyback itself? Aside from breaking down another set, where could I get a good replacement part?

A interesting puzzle...assuming that the squealing is not coming from the speaker but from the chassis...

A totally white screen takes a lot of beam current so your symptoms could be due to a failing HV shunt regulator tube or associated components. Most color sets use a hold down circuit designed to quickly reduce the horizontal sweep output - which can cause a current spike in the flyback transformer and the core can emit a strange hissing sound (sound level depends on core design). The current impulses can also result in the picture to wiggle. Many circuit designs feed back a few turns off the horizonatl ouput xfmr to set the bias on the phase detector diodes in the horizontal oscillator/AFC multivibrator. Leakage here can also upset set the DC balance in the rectified waveform from the sync sep that sets the grid bias on the multivibrator circuit. Again, the picture can wiggle. Finally, the B+ (usually 260 - 275 volts) that drives the hoizontal oscillator may have a lot of ripple during bright white picture scenes due to the increased beam current. A bad cap in the power supply could be the culprit too.

Role up your sleeves and dig in! :zoom:

It's not the speaker. I checked that already. :) No tubes to fail here though, this is a SS set.

I'm beginning to wish I hadn't junked the parts set I broke down to fix this set after I fell on top of it when I was totally sh*t-housed and blew up the picture tube. :/

A HV problem would make sense because the brightness dims somewhat sporadically whenever I hear this noise. I've never really had to mess around that much with internal circutry before, what would cause it to ripple? Bad caps? Corrosion somewhere?

How old is it? I used to replace yokes on 80s vintage Magnavox because they would buzz and/or squeel. Might be a loose core in the flyback, or in any coil in the horizontal circuit. If it's new enough to have a switching power suppply, it could be in that transformer.
Sometimes using a plastic stick to push gently on these will make the noise change when you hit the right one.
Of course, use all the usual cautions when working in these areas with the set on.

The wiggle you mentioned makes me think it might be something in a switching power supply (if the set is that new). Could be a bad electrolytic cap there. I always suspect the electrolytics.

The set is from November, 1986.

Switching power supply is how newer sets turn on and off (IE the sets that have a power button, rather than a pot or switch)?

Looks like the next logical step is to get a schematic (if there was one inside the set it's long crumbled to dust) and "poke around."

Thanks for all the suggestions.