Neil Gruending wrote:

Thanks for the reply.  One of the first things I checked was the power
supply levels - all are correct.

--
Bob Smither, PhD                                  Circuit Concepts, Inc.

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gbusg wrote:

Done.  All the supply rails look good.

The unit does not have that option.

I did this, but no change.  I wonder if the boot process is assuming
something that has been lost from the RAM.

Reset button?  Don't see that.

Agreed.

Will do.

Thanks for the feedback!

Bob Smither, PhD                                  Circuit Concepts, Inc.

---=======
Blessed is he who expects no gratitude, for he shall not be disappointed.
-- W. C. Bennett

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Smither@C-C-I.Com  http://www.C-C-I.Com  281-331-2744(office)  -4616(fax)

Artekmedia wrote:

Thanks!  I will check out the group.

--

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Bob Smither, Ph.D.                                      Bob@Smither.net

I have a Dream:
First, Ron Paul becomes the Republican nominee.
Second, Dr. Paul becomes President Paul.
Third, our country becomes America again.

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Bob wrote:

The Reset function can be invoked by hitting "blue" (keyshift) key +
SGL/TRIG (TEST/RESET). (This might be only labeled "TEST" in blue on some
versions.)

Good question. I'm not 100% sure, but at that point I'd still expect
Self-Test to conclude with a displayed error (such as  Calibration
RAM error, or RAM error, or ROM error).

So I'm still wondering what/why the CPU (U501) seems caught in an endless
RESET loop?

Does the instrument seem to respond to any front panel keys at all?

Just as a "sanity" check, it might be worthwhile to make sure all front
panel keys are free (and that none of them are stuck).

Sorry to hear none of the "easy" things were the cause so far.

--Greg

gbusg wrote:

Oops!  Found it.  Unfortunately activating it makes no difference.

Not at all - either plain key press or in combination with the blue key.

No difference in the endless cycle with any key press.

Me too!

Many thanks for the good suggestions.  I'm going to continue to poke
around in the digital section and see if I can find a bad part.

Best regards,

Bob Smither                                          smither@c-c-i.com

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speedy and public trial, by an impartial jury of the State and district
wherein the crime shall have been committed; which district shall have
been previously ascertained by law, and to be informed of the nature and
cause of the accusation; to be confronted with the witnesses against him;
to have compulsory process for obtaining witnesses in his favor, and to
have the assistance of counsel for his defence.
-- Sixth amendment to the Constitution of the united States

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Circuit Concepts, Inc.                                    281-331-2744

Bob
Is it possible that this  has been left in the "calibrate" mode ?  I seem
to remember that there is a DIL switch at the rear (number 8), for this
purpose. This is of course an instrument that is equipped with HP-IL, which
makes it a little less attractive, but otherwise a very well made DVM. Good
luck.
Roy

From: "Bob Smither" smither@c-c-i.com
Sent: Sunday, August 28, 2011 6:08 PM
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Subject: Re: [volt-nuts] HP3468A

Roy Phillips wrote:

Thanks for the tip.  I have tried both positions of the calibrate enable
switch - unfortunately no change :-(.

--

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Bob Smither  Office: (281)331-2744  Fax: (281)331-4616  Bob@Smither.net
http://www.tx.lp.org                                    LPT WebMaintainer

---========

gbusg wrote:

Well, I may have found something.  Signature analysis points to a
defective control ROM, U502.  Markings indicate this is a Mostek
MK36752P.  HP part number is 1818-1753.  The pin out looks like that of
a Motorola MCM68764 UV erasable PROM, which I can get on EBay.

So, here is a real long shot - any chance someone the volt-nuts list
would have a listing of the contents of this PROM or know where to find it?

(I will be asking the
hp_agilent_equipment@yahoogroups.com Yahoo group as well.)

Thanks!

Bob Smither, PhD                                  Circuit Concepts, Inc.

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"Neither slavery nor involuntary servitude, except as a punishment for
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within the United States, or any place subject to their jurisdiction.

Section 2.a of Proposed House Resolution 163, 108th Congress:

"It is the obligation of every citizen of the United States, and every
other person residing in the United States, who is between the ages of
18 and 26 to perform a period of national service ..."

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