[Yaesu] Perplexing Problem...

[KB0NLY]

Hmm.. Ok I will do some schematic hunting on this.

I can tell you that I have owned other 2400 and 2500 Yaesu's and used them 
in this fashion and they didn't exhibit this problem, so this radio must 
have something wrong.

73,

Scott


----- Original Message ----- 
From: "Jim Hargrave" <w5ifp at gvtc.com>
To: "Yaesu Reflector" <yaesu at mailman.qth.net>
Sent: Tuesday, October 13, 2009 4:02 PM
Subject: Re: [Yaesu] Perplexing Problem...


> Scott,
>
> I'm not familiar with the schematic of the 2400, but here are some
> possibilities:
>
> I would check the memory power line going to the CPU. What voltage you are
> getting with the radio off? Its possible that the radio power switch is 
> also
> switching the backup battery out of the circuit when it is turned on in
> order to preserve battery power. If so then you would kill the backup 
> power
> when turning off the power supply leaving the backup battery turned off.
>
> Another problem could be a steering diode in the memory power circuit. 
> Most
> radios have a diode that provides the memory power which in essence 
> switches
> the battery out of the circuit because the source voltage is higher than 
> the
> battery voltage. If that diode is shorted, then the external power supply
> circuitry could pull the voltage down too far to retain memory.
>
>   * 73's Jim W5IFP *
>     w5ifp at gvtc.com
>
>
>
>
>   >-----Original Message-----
>   >From: yaesu-bounces at mailman.qth.net
>   >[mailto:yaesu-bounces at mailman.qth.net]On Behalf Of KB0NLY
>   >Sent: Tuesday, October 13, 2009 7:55 PM
>   >To: Yaesu Reflector
>   >Subject: [Yaesu] Perplexing Problem...
>   >
>   >
>   >If anyone has been following along here i got a hold of a used
>   >FT-2400H that needed a few repairs.  I got the memory battery
>   >replaced and it now retains everything when shut off and
>   >disconnected from power, i shut it off and shut off the power
>   >supply to it yesterday morning and went back down this
>   >afternoon and turned it all on and lo and behold it was holding
>   >its memory and bandsplit info now.
>   >
>   >A quick note on the CPU jumpers and bandsplit, never did get
>   >that working quite right.  It only works 144-148Mhz on both
>   >transmit and receive, its supposed to cover 140-174 on receive,
>   >i tried the procedure of holding both the up and down buttons
>   >and turning the radio on, had to borrow a mic to do that, and
>   >it still stays at 144-148, so oh well i can live with it.
>   >
>   >The problem is now very perplexing as to whats going on.  I was
>   >planning on controlling power to the radio externally via a
>   >relay for APRS, adding an ignition sensed and timed relay to it
>   >so i don't have to remember to turn the radio on and off, but
>   >for some reason this still blanks the radios memory.  Let me explain.
>   >
>   >Radio turned on, if you shut off the power source to the radio
>   >and then turn it back on the radio looses all settings and
>   >memories.  It doesn't seem to matter if its a quick off and on
>   >or a long off and on, it just looses its memories unless you
>   >turn it off with the power button on the radio.
>   >
>   >As i said, i already replaced the memory battery, checked its
>   >voltage, and confirmed that the radio will hold its memory for
>   >more than 24 hours without any power source connected, but
>   >shutting off the supply voltage to it with the radio on seems
>   >to wipe all memories.
>   >
>   >Any ideas??
>   >
>   >73,
>   >
>   >Scott  KB0NLY
>   >
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