Tek 2467b Test 05 errors

[StefanS]

Hi Everyone,

I'm definitely a newb to electronics repair, so I wanted to get some advice about my Tektronix 2467b.  On startup, the scope errors out with one of two codes: "Test 05 Fail 04" or "Test 05 Fail 42".  However, if I run the diagnostics (single time or loop), test 5 passes.

Generally, the scope seems to be behaving itself (nothing obvious).

Any suggestions on where to start or why it is behaving like this?

Thanks!
Stefan

[JimS]

Hi
From the 2465B/2467B service manual (pg 6-12)

Test 05, Lit Led - ADD, Routine name - Main Board, ...
Error Code - Error Code Meaning
01               AUTO LVL failed to trigger.
X2               Negative level not negative enough.
X4               Negative level too negative.
2X               Positive level not positive enough.
4X               Positive level too positive.

From test description (pg 6-15)

Main Board (Test 05)
The auto level triggering feature (a routine stored if firmware) is operated to detect
the peaks of a line trigger signal.
Detected peaks are compared to expected values to verify operation (and calibration)
of interrelated signal processing circuits.

Test checks:
Line trigger source, the A Trigger generation circuitry and control DAC U2101
(located on the control board, diagram 2)

From my experience with the 2465B/2467B series I would start with:
Get a copy of the service manual from www.tek.com (PN- 070-6863-00)
Check the power supply voltages on the main PCB (bottom board) at J119.
If possible check the ripple on the voltage sources.
I have seen leaking electrolytic capacitors in the scopes power supply assy.
More often in one of the negative supply's Vs one of the positive supply's
The manual also says to preform a complete adjustment on the scope.

Good luck
JS

[StefanS]

Thank you, Jim.  Any idea why it would appear to pass test 05 when I initiate diagnostics manually?

-Stefan

[peter-h]

Would anyone have any great ideas for Test 05 fail 42 on a 2465B?

I have the service manual which shows the above reasons, but how does this map to the circuitry?

Is there something obvious which can be probed?

The triggering works on Normal, and (for a given signal) it works on Auto if Normal was used beforehand to get a stable trace.

[KCT_99]

This might help, I run into a similar problem, seems to be a very common problem.

https://www.eevblog.com/forum/testgear/2465bct-error-test-05-fail-44-(24)-trouble/msg2508813/#msg2508813

[peter-h]

Thank you; I posted my question there. A lot of stuff on google but not much that's conclusive. The big circuits under heatsinks, say U500, are presumably not serviceable...?

[KCT_99]

Well, yes the large custom chips are permanently attached to the heatsinks and can be easily replaced.

But they do not cause Test 05 errors !

The DAC circuit does cause this error as discussed in the link I posted.