Re: Concentric A and B time-base knobs/interlocking

Tom Gardner
 

On 15/07/18 14:13, Colin Herbert via Groups.Io wrote:
Hi,
I thought that I recalled some discussion on dismantling these A and B time-base knobs safely, but I can't find it now. My problem is that I have a 466 which looks to be fine so far, except for the B (delayed) time-base settings. The A time-base looks to be ok (thought I haven't checked its calibration fully), but pulling out the knob to select the delayed time-base settings results in the knob simply turning freely with no detent positions. Also, the knob cannot be turned to the locked position while pulled out, only when released back to the "in" position. I thought that I had seen a "bright-up" spot when switching to "A INTEN" which could be moved with the delay time position control, but this can't be seen now. There is no evidence of a B sweep at all; the "BEAM FINDER" button only shows a bright spot.
I have tried removing the knobs on another dual time-base some time ago and found it troublesome to put it back together again, to say the least. Does anyone have any hints for me?
TIA, Colin.
475 rather than 466:
http://www.eevblog.com/forum/repair/renovating-an-early-tektronix-475-oscilloscope-a-few-random-hints-and-tips/

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