Don
I have always wanted a 3458A - but I am amazed at the number of faults you
fellows are encountering with this instrument - -this must make it a very
hazardous purchase, in particular from a private source !! I have both 3456
& 3457, which for some years have been faultless - maybe because they are
less sophisticated ?
Roy
----- Original Message -----
From: "Don @ True-Cal" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Tuesday, August 04, 2009 3:29 PM
Subject: [time-nuts] Another 3458A problem
Hello,
Seems this is the month for errant 3458A DMMs. I have a unit that was
working fine and passing both the power on and full Self Tests. The unit
has been stored away for a few years and is very clean. After several days
of continuous error free operation, is started kicking out the error:
114 System Error – multislope rundown error
At first, the error was only every few minutes (all default power on
settings) but is now almost constant. I can clear the error and proceed
for a few more seconds. It is also the only error in the stack.
Suspicious of electrolytics, I checked all voltages and ripple on both
outguard and inguard supplies with everything looking good. I did replaced
some caps that showed barely low values. This unit is 11 years old. At
this point, I am reasonably sure it is not power supply related. I am also
sure it is not a cal related condition as I started a procedure and it
would not get past the first offset section – same error.
Does anyone have any documentation of knowledge of this error? ERRSTR 114
is not mentioned in the Assembly Level Repair manual. Thanks.
DonRegards...
Don
________________________________
From: Dick Moore <[email protected]>
To: [email protected]
Sent: Sunday, August 2, 2009 2:08:08 PM
Subject: Re: [time-nuts] new request for 3458A info
On Aug 2, 2009, at 5:00 AM, [email protected] wrote:
Message: 4
Date: Sun, 02 Aug 2009 03:00:06 +0200
From: "Dr. Frank Stellmach" <[email protected]>
Subject: [time-nuts] 3458A info
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-15; format=flowed
Dick,
did you already try an ACAL DCV, or ACAL ALL from the front panel?
Maybe the false cal constants will be set correctly.
In the calibration manual, its explained, which constants are set by
atocal (and cured), and which one are set by basic calibration,
requiring external standards (10 volt, 10kohm).
I think, DAC Vos and 10V gain are set by ACAL.
Frank
Yes, tried all that. Last night I gave up and opened the box, which I had
been reluctant to do -- DC board had burned components right in the
center. There are 2 unrecognizable ICs and a handful of resistors, etc,
and a badly charred board. Probably unrepairable. Have no idea what could
have happened to make it so bad without also killing the power supplies,
which are AOK. Shouldn't have been anything on the input, which is
protected against over-voltage/-current. Too bad.
Thanks for all the advice and tips.
Dick Moore
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