Quote:
Originally Posted by old_coot88
From the "thought i'd seen it all" department, this has gotta be the first problem I've ever seen caused by the HV being too high in a BW set. Color sets, yes. But never a BW before this one. 
Anyhow, if adjusting the horiz. drive hasn't reduced the HV sufficiently, it's easy to cut back the gain of the output tube itself (the 6AV5). One method is to put a resistor in series with the cathode (say 100 ohms as a ballpark starting value). The other is to reduce the screen grid voltage (on pin 8). This is the method I would try first. Assuming you don't have a resistor decade box or a resistor assortment on hand, go to RadioShack (ugh  ) and get a card of 2.2K half-watt resistors. Locate the 5.6K screen grid resistor R84. Open one leg and insert a 2.2K resistor in series with it. Bring the set up and see what the HV reads. This will give you a ballpark indication of which way to go with R84, ie., whether it needs more resistance or less. If it needs more, add another 2.2K in series. If that's too much, you can make a 1.1K by paralleling a couple of the 2.2K.
The caveat is, if you succeed in getting the HV down and the arcing cured with the set at full line voltage, the width may be reduced too much. I'm betting the width will still be sufficient. If it's not, then a new plan of attack is in order. oc |
Decided to go with Bill's suggestion on this one. I stopped at my local antique electronic shop (sorry just couldn't bring myself to go to Radio Shack) and get myself a handful of resistors. After two hours of shooting the breeze with Don, which if you know Don is a very short conversation, I headed home ready to tackle the task at hand. It took two 2.2k resistors in series with R84 to bring the anode voltage down to the point where the 1X2 stops experiencing high voltage failure. At full line voltage the anode is still way over spec at 16kv, or at least that's what my meter and high voltage probe reads. There is no sign of high voltage problems any more, no sparking 1X2, no corona discharge around components in the hv cage, no black vertical lines on the screen. Tonight I go to sleep for the first time with a full screen raster
. Granted there is no video, the horizontal isn't linear, and the screen is full of retrace lines but I'm pretty happy to be at this point
.
Just some questions/concerns at the end here.
Horizontal size and Horizontal linearity control slugs do nothing to the screen when adjusted.
Can some one tell me what Horizontal Drive and Horizontal AFC are/do?