[time-nuts] OT: Question on dead HP34401
paulswedb at gmail.com
Tue Dec 11 20:40:39 UTC 2012
Two comments the manuals available on agilent
What on earth is a crossguard?
On Tue, Dec 11, 2012 at 3:16 PM, Bruce Griffiths <bruce.griffiths at xtra.co.nz
> Ulrich Bangert wrote:
>> 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
>> 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
>> is that there is a 7 kHz repeating reset signal on the reset line that
>> NOT come from the voltage regulator's reset output but must be generated
>> 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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> Which reset?
> Assuming the circuit is the same as mine (Setember 1991 -October 1991)
> The Floating logic reset, the Earth referenced resets: 8051 reset
> (generated by absence of crossguard comms) or the 9914 reset?
> The only ASICS are U101(analog switch array), U102(resistor array) and
> U501 (gate array), none of which generate a reset.
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