Re: 2465B - Weak Readout Intensity

Chuck Harris

The trigger hybrid triggers the A and B time base hybrids,
and they feed their gate signals (/SG) into the the PAL U975,
which chews on them, and feeds FF U980B, which talks back to
the PAL, which passes it on using /SGB goes back to the
trigger hybrid, and display sequencer.

So, it could be the trigger hybrid, the sweep hybrids, the
PAL (clean its socket), and U980B's flip-flop.

There is a Parametric Measurements flow chart, you should look

My recollection is it is usually the trigger hybrid, the trigger
hybrid's socket, or the PAL's socket.

-Chuck Harris

flanneltuba@... wrote:

I tried cleaning and deox'ing the Trigger Hybrid, but the problem remained. Swapped it out with another chip, and still not change, or at least no meaningful change. (Curiously the error text from the chip out of a 2465 was just, "NOISEY OR APERIODIC SIGNAL" without the "CH1:" prefix.)

I tried feeding a higher signal amplitude into the scope, 2v PP instead of 500mv PP, with no change. Then tried some higher frequencies. Previously I had used 5kHz; I bumped it up to 20MHz and the scope at least made an attempt to read the signal frequency, but it was way off. It assessed the 20MHz signal to be 33.94MHz. The same signal measured with the cursors on 1/t was right at 20.4MHz. See the pics I posed at the top of the Album:

The auto Measure feature does take correct aptitude readings. It read a 2.0v PP 2kHz sine wave right at 1.998v PP. There's some hope, I suppose. Aside from giving it a real calibration, it does seem to be working quite well. I was able to get it to trigger on and display a signal up at 1.0 GHz, though the cursors marked it at 797MHz. Not bad!

So it's down to this last little foible. I can certainly live w/o the frequency measurement feature, but, heck, why stop short of perfect?

Any other thoughts on my aperiodic little 2465B?

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