#61
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ok, is the set fixed now?
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#62
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well no its not fixed now the hv pot only raises up to 14kv and seems stable not jumping around but its to low.i will be pulling up the 6bk4 cap and see the hv then ill be pulling the 12by7a and see the hv and ill be lowering each color gun to see again if the voltage goes up to see if infact i did not get rid of the shorts that i found in the crt the one gun that is turned down that raises the hv to where it should be where may indicate a short condition in the crt, at least i think. after removing the shorts in the crt neck and i seen the little arcs i did get a much better picture but it may need more.i also double checked the 2 1.5 meg resistors and they are 1.600 and 1.617. something is clamping the voltage for sure but what i dont know and i hope its not the crt, the crt has very good emissions, good is 200 or more and it tests almost 400.
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#63
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pls one thing at a time.
did the CRT tester indicate shorts? |
#64
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it did not indicate a short for what my tester shows for shorts but a friend that worked on these in the 60s tells me that a certain short i think he said cathode may not show on my tester. all it showed was very good emissions so i went ahead and used the remove shorts function ONLY and there were little sparks on each gun one a little more then another.
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#65
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Do you have a HV prob
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Audiokarma |
#66
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Do nothing more to the CRT with the tester, put the CRT tester away.
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#67
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ok, done. and the chassis is on the bench. i have a 30kv probe.
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#68
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with everything hooked up, turn the brightness all the way down, read the HV at the anode of the CRT, and then read the focus voltage at the CRT. the focus voltage will be at the pin that is in between the other pins on the crt, (there are open spaces between it and the others). You can read this by tracing the black lead from the CRT Plug back to the fly and touching the HV probe there.
after doing this try it again with the shunt tube disconnected (the top plate cap removed, be careful the plate cap has full HV so make sure its not near a ground. what are the voltages of the CRT HV anode and CRT focus with with the shunt tube connected and disconnected. brighteness all the way down. |
#69
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ok very good i will be doing this, the first chance today i get to put the chassis back in.
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#70
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ok, bright down black wire to focus is 2kv while the crt is 14kv with the hv pot still alittle over the half mark the way it was when i got it, it will adjust up to 18kv but thats max. hv moves around alittle on scenes. bright down focus wire just a spec over 2kv and crt just touches 30kv with 6bk4 cap off.
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Audiokarma |
#71
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Next you need to determine if the CRT is drawing the current down or the shunt, I doubt its the CRT since the HV is low even with brightness all the way down.
Next unplug the CRT socket read the HV again with shunt cap on and then shunt cap off, HV adj to max does the schematic show a jumper in the cathode circuit of the shunt tube (since you are positve there is no 1k resistor), but I am getting ahead of myself so just do the above test, CRT socket on and off, HV setting to the max. I have an idea of something that could cause the shunt to conduct when in should not, but since I dont know if its the problem or not I dont want to mention it. |
#72
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crt plug off 18 kv but adjusted up max, hvpot, and it will adjust down as well. cap off and crt plug off runs up to just touch 30kv.
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#73
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ok so it looks like the CRT is cleared, back to the shunt tube.
have you tried a new shunt tube? |
#74
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did you find a jumper inlieu of a 1k resistor to check the shunt current?
For clarity it would be best if you would quote me and then respond. |
#75
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i tried 3 new ones, GE, RCA, RAYTHEON.
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Audiokarma |
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