By the way, I no longer have a K3 or P3 (lost in a house fire) so this
is from memory...
> Since the internal display seems to show OK, no matter how briefly,
> I'm thinking this is not an internal display connection issue.
Agreed.
> This seems to be a power on reset issue of some sort.
Can you send/receive RS-232 commands to the P3? If so, then the power
must be on.
If you haven't already, I would try moving the power-on jumper (on the
rear-panel I/O board at the back of the P3) to the "always on" position
(jumper pins 1 and 2).
> I take it that the 3.3V supply is 'on' as long as 12V external is
supplied to the P3?
No, it's only on when the P3 is on.
What happens is that when the P3 CPU wakes up, one of the first things
it does is to enable the PWON signal to the I/O board which holds the
power on. If that is not working for some reason, then moving the
power-on jumper to "always on" should force the P3 to stay on.
Alan N1AL
On 2/26/23 12:22, Dave New, N8SBE wrote:
Alan,
Before I got the chance to look into your idea of possibly bad display
connection,
I DID reload a saved configuration into the P3 using the P3 Utility,
and it restored
the high-res setting on the external display.
After power cycling (the generator quit unexpectedly due to a low oil
sensor),
now I can't get the external display on at all, but interestingly, the
internal
display comes up briefly with the P3 Boot Loader and Checksum Test
messages, and
if it's been a while since I've tried to power up, I get a brief
spectrum display
with the message, Waiting for SVGA, then it goes blank, apparently
with an internal
power fail, since every time I push the Power button, I get the same
sequence.
Since the internal display seems to show OK, no matter how briefly,
I'm thinking this
is not an internal display connection issue.
This seems to be a power on reset issue of some sort. I note from the
schematic that
that Power button feeds SW_ON which is tied to INT4/A15 on the PIC33F
chip. I'm assuming
the PIC has that pin programmed for INT4, so pushing the Power button
is 'waking up' the PIC33F
with INT4, and it goes partially through the start up, and then fails
apparently failing to
latch 'on' from the momentary push button press.
I take it that the 3.3V supply is 'on' as long as 12V external is
supplied to the P3?
Thanks,
-- Dave, N8SBE
On 2023-02-24 13:23, Alan Bloom wrote:
Hi Dave,
Another possibility is that perhaps one of the display connectors has
come loose or is making a bad connection.
I normally wouldn't recommend this since these tiny connectors are
kind of tricky, but since the P3 isn't working anyway, there's nothing
to lose.
There are two surface-mount connectors located underneath the display
on the front-panel board: a 4-pin connector for the display backlight
and a 40-pin connector for the rest of the display electronics.
To access them, remove the front-panel board from the P3 and then
remove the LCD display by gently prying it free from the rubber
holder. Be careful so as not to put stress on the flex circuits going
to the two connectors.
Examine each of the connectors to see if it looks like the flex
circuits are properly seated in them. To re-seat one, open the
connector by using a fingernail to pop open the top. After
re-positioning the flex circuit, press the connector top down again
until it clicks.
As I say, this is a rather delicate operation (which is why the front
panel came pre-assembled in P3 kits). So you might want to consider
sending the P3 in for service and let the experienced Elecraft techs
handle it.
Alan N1AL
On 2/24/23 10:51, Dave New, N8SBE wrote:
Mike,
Thanks for the idea! I hadn't considered that mitigation.
Anyone else have ideas for a permanent corrective action?
73,
-- Dave, N8SBE
On 2023-02-24 09:13, Mike Flowers wrote:
Hi Dave,
If you have a way of sending P3 control commands to the P3, there
may be a
chance that you could the resolution of the external display set to a
useable value.
I've attached my copy of the P3 Programmer's Reference.
- 73 and good DX de Mike, K6MKF, NCDXC Life Member
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