K2 display failure

[Bob & Debbie Fish]

Hi Gang,
I have been tolerating an intermitant problem with the display on my K2
for several months now and finally I've decided to dig in and fix it.
Here is the problem, After powering up the radio, the LCD display will
go blank. Sometimes after 5 minutes , sometimes after 45 minutes. The
S-meter still works fine and the audio from the radio seems ok. I can
change frequencies and I get the expected sounds from the speaker. When
I first started experiencing this , I merely powered the radio off and
then on and the display returned to normal operation. However, now the
problem is happening with greater frequency. Sometimes recently, I sit
down and turn on  the radio I will get no LCD display and I can power it
on and off 10 or 15 times in a row and still no display. I can come back
10 minutes later and get the proper display on the first power up. Also
sometimes when I change bands the display will only partially change, in
other words the right hand side of the display doesn't change only the
first few digits of the left side change. Many other peculiar anomalies,
too numerous to mention, have presented themselves recently.
Here is the problem, I cant figure out a way to get a meter in the
various places that might shed some light on this problem while the
radio is in a failed condition. Short of disassembling the radio and
tack soldering some enamel wire to various strategic points in the
circuit,  reassembling the radio, waiting for a failure, to make voltage
measurements and thereby make a reasonable guess as to where the failure
might be. Has any one seen this problem before or have an idea on a good
way to chase it?

Thanks in Advance,

Bob  K6GGO
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[Don Wilhelm-4]

Bob,

You likely have an unsoldered or poorly soldered connection on the Front
Panel Board.
Separate the front panel from the board and you can probe most
everything on the front panel board.

Do a visual check and you may be able to find it - check pin 1 of the U1
socket, that is a common one to skip soldering on.  Check the pin 1 of
all the rest of the ICs and pin 1 of the connector.
Those pin 1 places have round solder pads while the other pins are
rectangular pads and it is easy to miss the pin 1 solder connection and
not notice it.

73,
Don W3FPR

Bob Fish wrote:

> Hi Gang,
> I have been tolerating an intermitant problem with the display on my
> K2 for several months now and finally I've decided to dig in and fix
> it. Here is the problem, After powering up the radio, the LCD display
> will go blank. Sometimes after 5 minutes , sometimes after 45 minutes.
> The S-meter still works fine and the audio from the radio seems ok. I
> can change frequencies and I get the expected sounds from the speaker.
> When I first started experiencing this , I merely powered the radio
> off and then on and the display returned to normal operation. However,
> now the problem is happening with greater frequency. Sometimes
> recently, I sit down and turn on  the radio I will get no LCD display
> and I can power it on and off 10 or 15 times in a row and still no
> display. I can come back 10 minutes later and get the proper display
> on the first power up. Also sometimes when I change bands the display
> will only partially change, in other words the right hand side of the
> display doesn't change only the first few digits of the left side
> change. Many other peculiar anomalies, too numerous to mention, have
> presented themselves recently.
> Here is the problem, I cant figure out a way to get a meter in the
> various places that might shed some light on this problem while the
> radio is in a failed condition. Short of disassembling the radio and
> tack soldering some enamel wire to various strategic points in the
> circuit,  reassembling the radio, waiting for a failure, to make
> voltage measurements and thereby make a reasonable guess as to where
> the failure might be. Has any one seen this problem before or have an
> idea on a good way to chase it?
>

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