#16
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To be more clear: Take the cap off the 6BK4, then run the set.
This will take the shunt regulator out of the circuit. By definition, the shunt regulator puts an additional load on a power supply of limited current availability. It relies on additional loading to provide voltage regulation. Think of the HV supply as providing enough voltage and current to run the picture tube. When the picture gets dark, beam current would go down, reducing load on the HV supply. Voltage would naturally go up. The 6BK4 should then conduct more, and load the HV supply source, and bring down the voltage level. Removing the HV lead, or plug at the end of the tube takes out the main current user of the HV supply, HV should go up as it has a very limited load at this time. Normally, the set should supply 20 - 25KV to your set with a mid brightness picture on the screen. You have to determine if the supply has a problem or if there is a problem with the tube, or the reg. It is fairly easy to disable the regulator. Then move on from there. Your tv sure looks like it's producing a nice bright picture. .
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Yes you can call me "Squirrel boy" Last edited by Username1; 03-05-2017 at 09:28 AM. |
#17
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Quote:
Check the value of the resistors around the 6BK4 grid, I'm sure you'll find that one of them has drifted out of spec. Could also be the HV pot itself, use your DMM. Once you've replaced the bad parts, you should be able to set HV correctly with the pot.
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Evolution... |
#18
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Quote:
Is it jumpered out, like it was recommended in another thread. |
#19
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Going to tackle it next sat. Excellent advice from everyone. Much appreciated. I want to keep this set for a long time so I want to get it fixed.
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#20
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OK this was missed by all. If you turn the brite down on any
set the pix should go black or nearly so. Fix this first as it causes an abnormal load on the HV. Start with a by the book set-up especially the G-2's & bright limit. Could be just someone set them too high to get a brighter pix. If not adjustments move to the vid amp & blanking tubes. I remember NO scenario where the HV will cause too much brite........ Normally I would start at the sweep then move on BUT the video is so far off it could be the root of the problem. 73 Zeno LFOD ! [QUOTE=VA561;3179850] Quote:
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Audiokarma |
#21
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Zeno You nailed it! I had previously mentioned that I couldn't get a dark screen. Not even close and the best I could get was 16Kv. As per your suggestion, After turning the brightness knob down as far as it would go, I adjusted the three G2 controls and got a dark screen and most importantly........25Kv! I then brought up the G2 knobs up slightly to where I thought I had a decent picture. I guess the the fact that I couldn't get a dark screen caused you to consider the G2 settings. Thank you so much. I now have a full screen and a pretty good picture. After a convergence is done, that should do it.
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