Products > Test Equipment

Tek 2465 Horizontal Sweep Issue

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tautech:

--- Quote from: kellymcdonald78 on April 19, 2024, 10:54:59 pm ---Not sure exactly what changed (reseating U700?) but my sweep is back :)

--- End quote ---
With a portion of intensified trace from the dual timebase.

kellymcdonald78:
And it's gone again :( Not sure where to go next, might need to see if I can borrow another scope to troubleshoot it further

MarkL:
On your probing of pin 18, the ramp will take as long as the sweep, approx. 10x the sweep setting to cover all 10 divisions.  If you're measuring with a voltmeter with the prescribed test settings, you'll never see the ramp because it's too fast.   One thing you could do is turn the sweep down to 0.5s/div.  The sweep across the screen will take about 5 seconds, and you should be able to see such a slowly changing ramp on a voltmeter.

Since you're getting a vertical deflection, you could also probe pin 18 with Ch 1, again at a slow sweep.  With this problem on your scope, what you should see is a dot slowly going up and then resetting, repeatedly.

What are you seeing on the back panel A GATE OUT?  A logic high here indicates that the A sweep has been triggered.

Does XY mode work?  Seems that it probably should given the other symptoms.

I would also try removing and gently cleaning the contacts with isopropyl on hybrids U500 (trigger) and U650 (display sequencer).  Don't mess with the nut on U800; it is prone to failure from mechanical stress.

kellymcdonald78:
I’ll take another look, been out of town recently. XY mode seems to work, and I’ll check the voltage on pin 18 to see what I see.

kellymcdonald78:
Brilliant idea using the scope itself on pin 18 (scope, heal thyself). I’m not seeing any change in voltage on pin 18 (I checked at variety of timing settings). Not seeing any change on pin 9 of U735 either,  which should be the  A sweep from U-700. I get a near constant -1.24 volts here. Tried swapping U700 and U900 again but no change

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