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  #16  
Old 03-27-2011, 04:39 PM
DaveWM DaveWM is offline
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if you get a chance would you pls snap a pic of your CRT neck. I don' think the blue lateral and the purity rings are in the right posistion on mine.
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  #17  
Old 03-27-2011, 05:26 PM
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miniman82 miniman82 is offline
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Wouldn't do you any good, what I have for blue lat is completely different than yours. The one mine has is metal...might not even be the right one. I also learned today that my set is missing the degaussing coil! Guess that explains the vacant 4-pin plug on the chassis. Anyone have one????
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  #18  
Old 03-27-2011, 08:16 PM
DaveWM DaveWM is offline
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wow, wonder how that came to be (no coil),
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  #19  
Old 03-27-2011, 08:25 PM
DaveWM DaveWM is offline
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ok blue intermittant still there, I poked around on one of the 6BL8's and you can make it flicker, but that just may be the shock going thru the board. I will try cleaning the sockets (again) but I need to try and isolate exactly where the problem is. Heck could be a tube with a short I guess (that would certainly account for a thermal issue). I am tired or working on it, so will button it up and give it some time off for pretty good behavior. One thng for sure, it has EXCELLANT color demodulation, no bleeding what so ever, passes the homer simpson test with ease.
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  #20  
Old 03-27-2011, 10:47 PM
DaveWM DaveWM is offline
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I fooled around with the scope, I get about 180pp on the horz drive, which is close to the 190 called out in the sams. I need to break out the VTVM to check but I am guessing based on the scope the drive is fine. I also checked the screen but did not use my VTVM and I dont trust a DMM on that reading since there is a lot of pulsing going on, need to use the VTVM like it says to, I just dont think they react the same to pulsed DC. On the DMM I had 175v (should be 210 per sams).

I set the horz bias so the HV is 25.5 per the sams setup (brighness all the way down). It has a great pic, brighness range looks right, but the HOT current goes up to near 300ma in some scenes (all white screen) most of the time its around 230ma. The HV with the brightness set to normal is about 22-23kv. My only issue is the fly gets pretty darn hot after about 30-60 min.

I tried bridging another VDR and was able to adj the bias to get it down to about 200ma with normal scenes, but then the HV was around 19 and the horz sweep was falling short about 1/4 inch on both sides.

I tried several 6KD6's all about the same. I wonder if a HV rectifier or Damper could affect the fly load?
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  #21  
Old 03-28-2011, 07:49 AM
old_coot88 old_coot88 is offline
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Quote:
Originally Posted by DaveWM View Post

I tried bridging another VDR and was able to adj the bias to get it down to about 200ma with normal scenes, but then the HV was around 19 and the horz sweep was falling short about 1/4 inch on both sides.
Dave, in cases of borderline width and you've exhausted all avenues, there is a little trick that often helps. If you happen to have some 6KV rated disc ceramic caps of around 68pf, 82pf and 120pf, what you do is take the smallest one first (the 68pf) and put it directly across the damper, cathode to plate. This will kick the width out a quarter inch or so on both sides. If it's not enough, sub the 82pf, and if still not enough, try the 120pf.
Each stage will also drop the HOT current by 5 milliamps or so, which you can compensate for with the bias or by upping the screen grid voltage.
You can only take this mod so far, because each stage also drops the HV a bit (as in the old saying "there is no free lunch"). But there is usually a compromise where you have adequate width with reasonable HOT current and decent HV regulation. This situation also often crops up in Admirals using the 6KD6.
Bill(oc)
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