[Yaesu] FT-2600M Memory Loss

Sun, 11 Aug 2002 00:50:08 -0400

 I looked again at my notes from my last unsuccessful try at
 fixing the memory problem.  One thing I noticed this time because
 of your reference to the Azden problem was Q1030 a M51951 three
 legged thing that I assumed was a regulator.

 It turns out the M51951 isn't a regulator at all but a "voltage
 detecting, system resetting IC".
 see http://doc.what-trend.com.tw/pdf/14560.pdf

 It also turns out there is a Schmitt trigger internal to this chip.

 The input to the M51951 is set by R1171 and R1340 as a voltage
 divider both 4.7k.

 I'm considering changing this ratio so the chip causes a CPU
 power down at a higher voltage. I think I should also move the
 extra caps I added to the output of Q1028 to the input pin. Q1028
 is a three legged 5 volt regulator.

 Of course I could quit while its still working ;-)

 Thank you...

 WA4TUK

> > -----Original Message-----
> > From: [email protected] [mailto:[email protected]]
> > Sent: Saturday, August 10, 2002 11:00 AM
> > To: [email protected]
> > Subject: Re: [Yaesu] FT-2600M Memory Loss
> >
> >
> > While this may not have any bearing on your problem, the Azden PCS-4000
> > initially came out with the same problem.  The cause in that
> case was the
> > input voltage.  When it decayed slowly, the set was unable to determine
> > that the micro should be placed into the "sleep" mode.  If the switch on
> > the set was opened instead, there was a sudden drop in voltage and this
> > could be detected and the micro placed in the proper mode.  Azden had to
> > add an additional transistor to act as a schmitt trigger to the line
> > going to the micro.  This cure the problem.
> >
>