#61
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Say hey. if you got the K down to 200ma., great. The dip is usually much sharper than you describe, but if it holds at that value, what the hey. It wouldn't hurt to keep the meter on it for a while. Gotta luv the Simpson 260 huh?
It doesn't sound like you have any heat problem to speak of. The power xfmr will run pretty hot to the touch. The fly will get fairly warm. Sheet metal will warm up from radiant heat off the hot tubes. The hiss sorta remains a work in progress. |
#62
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Quote:
A fellow tech had sent his wife to class with his old meter to save a buck or two. Not even the instructor knew how to use it, but they figured out enough to set it to resistance and had gotten the manual out and found out that they had to zero the meter. Well, the meter wouldn't deflect but about half way. I knew that the batteries were dead. I told her that I had a digital meter that would suit her needs for the class as well as any other (which was true) and that I would trade her even. I told her that I was pretty sure that it was the batteries, but I wouldn't know until I changed them and I would take a chance on it in a trade. She was happy; I was VERY happy! Yellow case and all; like new. Anyway, thanks for all the info. I feel better about a lot of things except the lack of dip point that you mention. I knew that there should be a more profound effect on the current while turning the slug. Actually, it was pretty close to begin with and turning the slug only brought it down a bit. On the hissing, I might double check the H.V. rectifier and regulator.
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
#63
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try moving the HV filament leads around. The insulation may be breaking down on them, and they run right next to the cage.
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#64
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Quote:
Hope I can get it to stop. It's not an actual arc or loud snap, but more like a hiss which is still an arc of some sort, just not the really bad kind.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
#65
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Do you smell any ozone from the HV area?
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Audiokarma |
#66
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Maybe you have already done this, but I always clean the inside of the HV cage -- and everything inside it -- with isopropyl alcohol. Great for removing any grease or black soot. Even if it doesn't magically cure your hiss, it might make it easier to see what's going on.
Phil Nelson |
#67
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Good job , now like stated make sure everything is clean including the pins in the tube sockets , also post when you start tackling the color issue.
btw the glow inside my rectifier is blue/green in color. mike |
#68
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No, can't say that I smell anything. Just hear the hiss and see the blue glow inside of the rectifier, and of course the resultant interference on the screen. I only mention the blue glow inside of the rectifier because I expected to see something when I turned out the lights, but that is all that I saw.
Perhaps it just wasn't in a viewable area. I have had a number of sets through the years to have sharp solder joints or whatnot causing arching, not a hiss, but actual arching. Seems like a long time ago I had an old color set like this that was doing this and it was just moisture around the H.V. lead to the C.R.T. Perhaps I should check that just to be sure. They are in close proximity, so maybe I mistook the sound's origin.
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
#69
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If you have a length of flexible plastic tubing, you can use it as a sort of stethoscope to track down the source of the noise. Sometimes it's surprisingly difficult to pinpoint a noise source.
Phil Nelson |
#70
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A HV Rectifier tube that is glowing blue is getting gassy. 3AT2's are cheap and hopefully you have some spares to compare. Gassy rectifiers will take out flybacks!
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Audiokarma |
#71
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If the HV rectifier is gassy it will run hot. See if it feels inordinately hot (after you discharge CRT of course).
Last edited by old_coot88; 02-24-2014 at 09:09 PM. |
#72
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oops on my end I was referring to the 6BK4
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#73
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I seem them give off a ghastly green around elements on those when shunting a lot (dark screen).
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#74
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Just a side note, I have had my eye on a certain notorious for failing "bumblebee" capacitor for a swap out just for general purpose. But before doing that I wanted to see what circuit that it involved. Turns out that it is a .01 600V cap (C117) that looks to be in parallel with what looks like 3 grids maybe inside the c.r.t.
So, I'm missing color but I don't think that this is the cap that would be one that would take it out leaving behind a good black and white picture. I probably still should get rid of the cap just based on the failure rate. I guess right now I am in the stage of repairing the set as opposed to just jumping in there and replacing every cap with no regard for actual troubleshooting. But even when I get it right I do plan on replacing most of the caps. I may keep the multi section cans as I have found them to be pretty darned tough.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
#75
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Yesterday I turned the set on to see if I could find a lower dip point than the slightly over 200mA (more like 210) that I measured. To my surprise I looked at the screen and the color had come back, nearly perfect. But it didn't last long and then it was gone.
At least I know that whatever is going on is probably something pretty simple. I cleaned all of the tube pins and sprayed the sockets when I first brought the set home, so it may not be THAT simple. I need to check the color related tubes again for shorts and also that H.V. Rectifier for gas since I still have the aggravating hiss reeking havoc on an otherwise crystal clear picture. And B.TW. I disconnected one end of that .01 bumblebee and it measured dead on with a D.V.O.M. capacitance tester, so I just tacked it back in place. I know that it along with the other brown drops need to go if I am to use the set regularly. As I stated before, I sort of like doing the repairs and learning something rather than shotguning a bunch of new caps in. Indeed, my way is probably much more trouble than the shotgun method of repair by luck. Especially with the lack of some useful equipment like a very badly needed oscilloscope.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
Audiokarma |
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