Re: Tek 2467B Erratic Intensity controls


Chuck Harris
 

Hi Siggi,

Yes, I keep forgetting they did that. Putting a
cheap little LM311 on the A5 board simplifies the
circuit board routing greatly, and keeps the noise down.

The trigger hybrid is used as the comparator for
anything related to parametric measurements... and,
well the trigger.

I don't think I have ever seen that LM311 go bad...

Thanks for keeping me honest.

-Chuck Harris

Siggi wrote:

The comparator U2510, an LM311, is used to compare the DAC output to pot
readings, and the MPU uses this with successive approximation to make a
software ADC. This is described in the “Theory of Operation” section.

The trigger hybrid is not involved in pot scanning, though otherwise it
works the way Chuck describes it.

On Sat, Nov 30, 2019 at 04:49 Chuck Harris <cfharris@...> wrote:

There is no ADC part in the 2465 family scopes.

There is a DAC that is used as a part of an ADC
that is made from the DAC, CPU, MUX's, Sample and
Hold cells, and the trigger hybrid. The trigger
hybrid is used as the comparator that compares the
DAC output to the pot's wiper voltage.

The voltages get to the trigger hybrid by way of
a pair of muxes.

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