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  #46  
Old 11-29-2018, 10:58 PM
Electronic M's Avatar
Electronic M Electronic M is offline
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Quote:
Originally Posted by old_coot88 View Post
Doesn't the '25 have a Kine Bias switch? If so, it might be dirty. Try cycling it a few times with a shot of cleaner.
Could be... its been about 2 years since I last saw the inside/back of one...
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  #47  
Old 11-30-2018, 04:29 PM
ZenithNut ZenithNut is offline
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Quote:
Originally Posted by old_coot88 View Post
Doesn't the '25 have a Kine Bias switch? If so, it might be dirty. Try cycling it a few times with a shot of cleaner.

Yes it does. The thing is it had everything working when I brought it home. Niw that ive done work on it i have this to figure out.

I replaced the boost diode with a 1n4007 and this other diode labled ge gecr-2 with a 1n5408. I also replaced a few small value e caps here and there.

Last night i was wondering why the h output current would go up 50+ma with the hv rectifier in circuit so i swapped the 6bk4 shunt regulator with a 6el4 and a fat (i wanna say 10 watt) 600 ohm resistor under the shunt reg started going up in flame. The leads were green anx corroded looking. So now i have that to clean up.

I do know theres hv at the fly output though.
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  #48  
Old 11-30-2018, 06:37 PM
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You should get a HV meter or probe capable of measuring at least 30KV...The difference between 18KV, 25KV and 32KV is hard to discern drawing an arc, but can be the difference between no picture/slowly killing the CRT by drawing too much current to achieve normal brightness, normal operation, and the fly arcing and shorting internally...In some cases, wrong HV can be much worse than excessive H output current.

May want to check your HV rect is not shorting. If you have HV AC going to the CRT you will be able to draw an arc, but you won't have a picture.
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  #49  
Old 11-30-2018, 06:45 PM
ZenithNut ZenithNut is offline
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Originally Posted by Electronic M View Post
You should get a HV meter or probe capable of measuring at least 30KV...The difference between 18KV, 25KV and 32KV is hard to discern drawing an arc, but can be the difference between no picture/slowly killing the CRT by drawing too much current to achieve normal brightness, normal operation, and the fly arcing and shorting internally...In some cases, wrong HV can be much worse than excessive H output current.

May want to check your HV rect is not shorting. If you have HV AC going to the CRT you will be able to draw an arc, but you won't have a picture.
Well I did "test" the hv rectifier but that doesnt necessarily mean much, especially for sweep tubes were the tester doesnt even scratch the surface of the tubes operating range. I will think over what youve said.
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  #50  
Old 12-04-2018, 06:55 PM
ZenithNut ZenithNut is offline
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[QUOTE=Electronic M;3206251]You should get a HV meter or probe capable of measuring at least 30KV...The difference between 18KV, 25KV and 32KV is hard to discern drawing an arc, but can be the difference between no picture/slowly killing the CRT by drawing too much current to achieve normal brightness, normal operation, and the fly arcing and shorting internally...In some cases, wrong HV can be much worse than excessive H output current.

I got a two size plastic hex tool in my possession now. I also have a NIB Rca 3a3c hv rectifier coming in the mail. So now I can correctly adjust coils without breaking them.
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