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TAPR Trakbox

Ladies and Gentlemen,
    As some of you may remember, I recently posted a problem involving
the battery backup
circuit on my Trakbox. After a lot of very generous help from Vince,
KD7AI we believe we have
narrowed down the problem to a particular IC in the batt. circuit. To
provide a brief summary, the
initial problem resulted in two dead Li batt. after about 6 mos. I found
with a new cell that the
backup circuit drew a lot of current (304 micro amps). After replacing
the RAM and visually
checking for shorts, we checked U14 or the PST532A.
   We found that the Vo1 (U14-7) was going low at the correct time
(power off), Vcc (U14-6)
appeared to be working, although about 0.6v were present with power off.
BVcc (U14-5), however
only supplies 1.6v with power off and all of the backup ICs in place.
Removing the load allows the
voltage to rise to 3.17v. Vince is surmising that the PST532A may be
faulty, but neither he nor I
 have the specs for U14.
    If anyone has more information, knowledge, or could take some
measurements, I would really
appreciate it. The Trakbox works and has functioned correctly, except it
likes to eat Li batteries. : )
Again I would like to thank Vince for all of his gracious help, without
him I would never have
progressed this far.
            KB9RCA, Eric Pearson    EN53vb

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