[Elecraft] P3 Failure, and question

[Dave New]

  I've been experiencing intermittent failures of the internal  
display, as well as loss of at least one setting (Track/Fix).

I've been leaving the K3s/P3 powered on continuously, but recently  
started turning them off, to save some 'always on' energy while trying  
to figure out why our house is running about 1200 watts continuously.

So, when powering on the combination (the P3 is set to power on with  
the K3s power), very nearly always now, the internal display fails to  
come on, but the SVGA display always works.  Normally, cycling the  
power switch on the P3 recovers the internal display, but just  
yesterday, I had to cycle the power several times before it came up.

I'm now leaving things powered on, until I can troubleshoot what the  
issue is.  I did go as far as looking in the P3 manual to see if there  
is a coin cell battery in it, that might need replacing, but that is  
apparently not so.

I'm concerned about the loss of settings, which may point to a  
corrupted EEPROM.  Reflashing the P3 hasn't fixed this, and so far,  
I've not tried a 'factory reset' on the P3, which would lose all my  
settings.

Hope that helps,

-- Dave, N8SBE

Quoting Dave Cole <dave at nk7z.net>:

> Rick,
> A further thought on this...  Next time your P3 fails, can you try  
> and grab an image from it using the utility?  I just thought of  
> that, mine will not grab an image, when it is failed, so it is  
> probably not the backlight on mine.
>
> 73, and thanks,
> Dave (NK7Z)
> https://www.nk7z.net
> ARRL Volunteer Examiner
> ARRL Technical Specialist, RFI
> ARRL Asst. Director, NW Division, Technical Resources
>
> On 4/12/21 6:03 AM, Dave Cole wrote:
>> Rick,
>>
>> Thank you!  I appreciate the datapoint in this.  I was just looking  
>> over the schematic and came to the same conclusion...  It looks  
>> like a backlight problem to me as well...  I tried to find a  
>> datasheet on teh 4538 IC that appears to control it, but alas,  
>> nope.  I got mine to come back on by power cycling it as well...
>>
>> Hopefully someone has actually fixed this, and knows which cap...
>>
>> 73, and thanks,
>> Dave (NK7Z)
>> https://www.nk7z.net
>> ARRL Volunteer Examiner
>> ARRL Technical Specialist, RFI
>> ARRL Asst. Director, NW Division, Technical Resources
>>
>> On 4/12/21 5:27 AM, Rick Stanback wrote:
>>> My P3 does the same thing.  If i keep cycling power it eventually comes
>>> on and works.  I suspect there is a bad capacitor in the LCD backlight
>>> power.  I have not actually looking into it yet.
>>
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