Did you 4600 monitor gurus know this already?

Humdinger

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Made an interesting discovery today. Was in the process of rebuilding several 4600 chassies and after throwing the latest one in the test machine today, I had a monumental sync and hula issue accompanied by an apparent flyback whine. Swapped the cards around and still had the exact issue, so I ruled them out. Noticed that the activity on the screen kept perfect time and intensity with the whine.

Got on trusty KLOV and searched for "4600 flyback whine" and found an interesting tip involving sticking a toothpick down into the flyback's core sleeve to eliminate the noise. Some folks had had good results with that, but the logic behind it had me curious: what would cause the core to loosen enough to (I presume) "oscillate"(?) badly enough to a) cause the whine and b) cause the screen/sync interference?

Then I just happened to notice that a threaded shaft with a tiny nut on the end was trying to slide out of the flyback. Further examination revealed that one side of the flyback's "keeper" clip/retainer thingy that runs up one side and back down through the flyback had corroded and broken off. The only reason I saw this was because the bundle of wires that obscures this shaft (and only allows it to slide out if moved) was originally held fast with a zip tie, and I had cut that tie off earlier. This allowed the wire bundle to move out of the way and then the broken shaft slid right out.

Now say the following in the inflection of the narrator on The Curse of Oak Island: "A broken flyback core retainer? Could this cause the flybacks in thousands of 4600's to make a whiney noise and cause a person to erroneously believe that his flyback was failing? Could a new retainer fix both the noise and the sync/screen issue, thus enabling thousands of presumed-dead 4600's sitting on shelves across the nation collecting dust to come out of retirement?"

I figured that was just too easy, and that surely Entringer or Dokert or Layton or Buffett or some other monitor guru had probably figured this out long ago. But then I pulled 3 more salvage 4600 chassies off the shelf to check the retainers, and what do you know? All broken! Only one looked usable, but when I attempted to gently tighten it down on the chassis I was trying to test, it too broke under the slightest of pressure! Thanks to that, I now have no more retainers to install to see if indeed the problems disappear when the core is held fast.

I have attached a picture of 3 broken retainers. All had brown goo-like corrosion in the very spot where they snapped. It's not rust, but whatever it is must have altered the retainer's metal composition on a molecular level and weakened it internally. :) Has anyone else dealt with this issue? I have never seen another post discussing this retainer thingy and I'm sure I'm gonna have to have a dozen or so made just to prove this theory of mine. I'd love to hear from you guys if you know of a better way to handle this. Or you can just tell me I'm full of poo.
Thanks in advance.
 

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I've never seen this on 4600's, but the exact same thing happens on some of the old black and white Motorola monitors that are in Space Invaders, etc. On those that same exact clip you're talking about is exposed, so when it breaks, the core just falls right off the flyback.

Look really close at this one:

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And this one:

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This is how it's supposed to be:

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Yep. I can imagine it must happen a lot. I wonder if it makes any difference what material that retainer is made of? I'm gonna try to have my miracle worker metal guy make some of these because I'm dead in the water until I get some.
 
Man it sure looks like a coat hanger to me. I know it's threaded on both ends but I'd be really tempted to try and rig up a coat hanger with some plyers to twist it together or something to keep it in place. Of course that won't work if it passes under traces or something underneath whatever the ends thread through...
 
On the 4600, both ends go through a plate underneath the flyback that has a few soldered connections on it. I suppose the tension and the material are critical. It's very hard to bend, so any deformity that allows movement of the core must affect the picture if my theory holds water.
 
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Had a similar issue with the 6100 in my Tempest. Picture was pulsing like it had HV issues, when I pulled the cage, part of the retainer was rattling around inside. I had a backup NOS HVT, so I just swapped it out.
 
Update:::

Grabbed another 4600 off the shelf today, and didn't even bother looking at the nut and shaft; instead I just mashed down repeatedly on the top of the retainer on the side that normally breaks. When mashed, the retainer "squeaked" at the same pitch as the whine I heard when the power was applied. This suggests that it's probably not the core that oscillates, but the broken retainer itself. Does the high-frequency flopping around of the broken retainer leg inside the flyback disrupt the energy field within, causing the screen to do the hula and lose synchronicity? Do I have any idea what the hell I'm talking about?
 
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