Re: Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail

Chuck Harris <cfharris@...>

The Test81, Fail 03 is a combination of a Fail 02, and Fail 01,
which means that your reference oscillator is not calibrated.

The Test82, Fail 02 is hopefully spurious. Everything is closely
dependent on the oscillator being right. Let's just say that I have
seen it spuriously appear when the reference is uncalibrated, and
spuriously disappear after calibration.

Calibrating the CTT is easy, if you have a good clean frequency
standard that can make either a 50% duty cycle 1Vp-p square wave,
or a 1Vp-p low distortion sine wave at the correct frequency and

I use an HP3336B, with my GPS disciplined Rb lab standard as
the reference. The 3336B with the high stability option would
be fine by itself.

The HP is set to 1MHz, and makes a nice low distortion sine wave
referenced to the lab standard or internal reference.

-Chuck Harris

Jean-Paul wrote:

Chuck, with known good CTT board exchanged for the one in the failed scope, all cables properly reattached.

A5 board is know good and had no SMD leaky caps.

Only, partial success, CTT works but the following faults on self test:

Test 01 -06 PASS

CT TEST 81 Fail 03
CT Test 86 Fail 02
All others PASS

So really confusing results.

Your thoughts?


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