[time-nuts] Data Precision 8200 Voltage Standard

[Brooke Clarke]

Hi Skip:

Don't know this unit, but can comment on this kind of problem.  The most 
likely cause is a poor (oxidized) electrical connection.  So if there 
are switches, connectors, sockets, etc. involved then they need to be 
cycled a few times.  See What Goes Wrong:
http://www.prc68.com/I/HaT.shtml#Wgw

Another possible problem relates to electrolytic caps where the 
electrolyte has gone bad.  You need an Effective Series Resistance (ESR) 
meter to check them, see Capacitor Failure:
http://www.prc68.com/I/HaT.shtml#CF

Have Fun,

Brooke Clarke
http://www.prc68.com



Skip Withrow wrote:
>
> Realize a voltage standard post might be a little off-topic, but have 
> seen them discussed quite a bit, so here goes.
> We have a Data Precision 6-1/2 digit voltage and current standard, 
> which seems to operate except for the function of the front panel 
> voltage selection.  The mode and +/- voltage switch work fine.  We do 
> have the service manual, and the switches are read by the 
> microprocessor.  After checking the signals associated with the 
> switches (read signals are generated by the uP, and read back on the 
> data bus) my best guess is the the uP code my not be working correctly.
> The processor in this unit is a ROMed R6500/1 (cousin of the 6502).  I 
> fear that perhaps a bit in the ROM is being read incorrectly (in the 
> switch read routine).  My guess is that there is no way to read the 
> code out of this part.
> If any time nuts have a parts unit laying around I would like to try 
> swapping the processor to confirm my theory.  My next check will be to 
> adjust Vcc up and down and take some freeze spray to the processor to 
> see if I can find a point that it will operate, however, that will 
> certainly not provide a fix.
> Any help appreciated.
> Skip Withrow
>
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