Need assistance with vertical troubles on my silvertone - Page 2 - Videokarma.org TV - Video

roundscreen · #16 06-01-2009, 07:41 AM

You made mention of a power supply problem. Do you have 270 at test point c? Check r 505 and c 507. Try changing the tube again. Go through the board again and check for more bad connections and grounds.
Ed

jpdylon · #17 06-01-2009, 10:36 AM

the 270v supply is present at point C. R505 and 507 are 104 and 102k respectively. The 440v supply is present at the plate of the vert out (pin6)

andy · #18 06-01-2009, 04:21 PM

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jpdylon · #19 06-01-2009, 11:28 PM

Quote:

Originally Posted by andy

Start by checking the resistors....

Quote:

Originally Posted by sampson159

...i had a similar issue with my ctc 15.there is a resistor off the linearity control that may solve this.mine was almost identical.also a cap in the vertical by the output tube.good luck and that is a good looking roundie.keep us posted on this.

You guys called it. R136 is a dropping resistor that takes the 440v supply from the top of the vertical centering control and drops it to supply the vertical height and grid voltage through a voltage divider network. its supposed to be 150k - which it initially tested in circuit. However I was apparently measuring the total resistance of the circuit. When i pulled the resistor it turned out to be damn near 2 meg!

I discovered this when tracing back the voltage from the grids of the oscillator/output tube. when I got to R136 it had over 400 volts across it. If it were a 150k it would be on fire - so i figured it had gone way up in value. Pull it out of circuit - sure enough.....

I'll get a new resistor in there. Should take care of the problem.

jpdylon · #20 06-03-2009, 01:06 AM

Replaced the resistor and I've got my bias and control grid voltages back. Gonna pop the chassis back in and try to finish the setups.

Hopefully everything will work out.

*zenithfan1* · #21 06-04-2009, 01:04 AM

Good luck! I hope she works for you.

jpdylon · #22 06-06-2009, 09:10 PM

Bad news: The vertical restored and the set played for awhile. Then SNAP SNAP SNAP SNAP. The screen went dark momentarily then the breaker tripped.

The flyback melted down from a short in the primary. It wasn't running hot, was holding steady at 195ma on the HO cathode current. It just died horribly. I think I'm gonna call it quits on this one. It seems as though I'm just running into more nasty failure each time I try and run the thing.

I would rather take the excellent CRT outa this one and use it in another more favorable working set that needs it then continue to sink time into this set.