[time-nuts] OT: Question on dead HP34401

steve heidmann steveheidmann at yahoo.com
Tue Dec 11 21:18:02 UTC 2012

Long shot remedy : There is a front pannel push button sequence to turn off/on the display.

--- On Tue, 12/11/12, Ulrich Bangert <df6jb at ulrich-bangert.de> wrote:

From: Ulrich Bangert <df6jb at ulrich-bangert.de>
Subject: [time-nuts] OT: Question on dead HP34401
To: "Time nuts" <time-nuts at febo.com>
Date: Tuesday, December 11, 2012, 5:52 AM


I own a dead HP34401. On switching it on the display stays dark. It will
however react on pressing the SHIFT key. 

By changing pcbs against a working one the display board has shown to be ok.
There must be a problem with the main board. Without knowing whats inside
the ASICs make trapping the problem difficult. One strange thing that I see
is that there is a 7 kHz repeating reset signal on the reset line that does
NOT come from the voltage regulator's reset output but must be generated by
the processor or an ASIC. Anyone having an idea to that?

Best regards and TIA for your answers 

Ulrich Bangert
Ortholzer Weg 1
27243 Gross Ippener 

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