On 10 Mar 2016 17:15:23 -0800, you wrote:
...Unlike the bulbs in the z-axis DC restorer, the bulbs in the focus DCSo then... about the CRT circuit... DS47 is supposed to have a slight glow? Isn't that chain of neons supposed to be circuit protection?I have never noticed such a glow but I have not specifically looked
restorer do not hold the focus lead close to the cathode voltage so I
am not sure what purpose they serve.
I pulled the high voltage shield off of my 7854 and in a dark room,
none of the bulbs I could observe showed any activity. They were all
completely dark. When I first powered the oscilloscope up, I could
hear the crackling from the high voltage.
If there is a problem, hopefully work on the vertical amplifier around
U50 will solve it. If not, then I think it will be easier to just
shotgun rebuild the DC restorers instead of trying to diagnose them.
On 10 Mar 2016 17:27:36 -0800, you wrote:
If you guys are referring to the TO-8 and bigger canned hybrids in the vertical amplifiers, as I recall, on some models they had a plastic clamp type thing with a contact and wire lead that would both press the can leads into the socket pins, and make electrical connection to the can top, but only by contact force from compression, not a weld.Maybe there are two different versions of the package. All of the 400
MHz 7000 mainframes mostly use the same ICs and U50 is identical in
all of them but I have never had one of the vertical amplifiers apart
far enough to see if that lead is welded or attached with compression.
I do not think it matters though. There is no ground connection to
U50 that I have been able to find which would cause the observed
vertical deflection behavior. I think the lead is for shielding
Knowing exactly where in the circuit that wire connects would probably
reveal what it is for.