Re: 2467B focus/astigmatism anomaly...
Hi Raymond,toggle quoted messageShow quoted text
I agree that C4403 needs to be investigated. It will be
a week, or so, before I have any parts in hand to try.
C4403's intended purpose is to make moving changes to the
focus as the trace moves about on the screen.
Lifting one leg should stabilize the focus issues, if C4403,
or the dynamic focus circuitry, is part of the problem.
Something killed Q4402, be it old age, physical abuse, or
a random zap from C4403. Ordinarily, I would think that the
backwards diodes CR4410 and CR4411 should have protected against
all but the largest insults... Maybe they are compromised
Raymond Domp Frank wrote:
On Sat, Aug 17, 2019 at 03:14 PM, Chuck Harris wrote:The beam current definitely changes each time between turning intensity down and up again, as the case describes. Although I can understand a jittery/jumping Q4432 role, is there a reason *not* to suspect C4403 leakage? You *did* find a broken Q4402 earlier, didn't you? And where/how does the intensity down/then up scenario cause Q4432 to make its jump, since normally there's (virtually) no (change in) current in the focus electrode circuit? Still sitting on my earlier post...