Jean-Francois,
Saying what happened to U6 is only a guess, but I would suggest static
damage. Not necessarily static damage that happened recently, but
sometime in the past. However, if you had a nearby lightning strike
that caused a charge to build on your microphone cable or paddle cable,
that may be the reason.
One of the aspects of static damage is that it often does not fail
immediately, but at some time in the future. I suspect that is what
happened.
That is why we hear so much emphasis placed on using an anti-static mat
and a wrist strap when working with active devices.
Electronic devices are becoming more and more static sensitive, which is
a result not only of the technology used, but also from stuffing more
and more circuits into a smaller and smaller size. Before active
devices are mounted into a circuit, they are quite susceptible and must
be handled with care.
73,
Don W3FPR
Jean-François Ménard wrote:
You are right!! After U6 removed.... RP4 pin 5 and 6 are now at 81k ohm!!
U6 must be replaced
Thanks for your help..... But one question remains..... What did
happen to U6 ??
Jean-François Ménard
Le 08-09-19 à 09:52, Don Wilhelm <[EMAIL PROTECTED]> a écrit :
Jean-Francois,
Sounds like you are homing in on the problem. Try removing the
microprocessor and measuring the resistance between RP4 pins 5 and
6. If it is normal (81K), then you have a bad microprocessor input
at pin 30. If so, replacement of U6 is the only solution I know about.
73,
Don W3FPR
Jean-François Ménard wrote:
I also found another thing.....
Resistance check of Pin 7 and 8 of RP4 on the control board give me
81K ohm, but PIN 5 and 6 give me 19K ohm... should be 81K ohm too !!!
Le 08-09-19 à 09:29, Jean-François Ménard a écrit :
It seems that a resistence check on the control board give me a
hint..... U6 PIN 29 are inside spec, but PIN 30 give me only 16K
ohm and should be higher... around 80K ohm to 90k
The key jack seems to be good, R1 and R2 are OK.
Re-insert controler on RF board, nothing change
Le 08-09-19 à 08:11, Don Wilhelm a écrit :
Jean-Francois,
It certainly could be a faulty key jack, but it could be a
microprocessor problem too.
Turn the power down to zero for further testing.
Then check the voltage at the end of R1 and R2 near the key jack
- they are easy to reach if you remove the left side panel. The
voltage should be near 5 volts if there is nothing pulling those
inputs down.
Remember that the DOT line and the PTT line are one and the same
on the K2, so if that line is low the problem nay be in the key
jack or on the Front Panel board.
Should you find either the DOT or DASH lines near zero volts, turn
power off and make resistance checks to find out if there is a
short (maybe a solder bridge that has been dormant for a long
time). Those signal lines run direct to the microprocessor, so
there is only the jacks, PC traces, and the microprocessor involved.
73,
Don W3FPR
Jean-François Ménard wrote:
It seems that something let my K2 stuck in TX mode. I removed all
module and put appropriate jumpers (unmod kit). Still in TX when
powered ON. I checked this using my DL2 dummy load with my
multimeter.... I always have output power !!
Could it be a defective KEY jack that is jammed? I have nothing
plugged......
Le 08-09-18 à 23:33, Don Wilhelm a écrit :
Jean,
This is strange - the second case of similar behavior reported
on the reflector today. Could it be a case of the 'phase of the
moon'?
When the K2 is in transmit state, the behavior will be as you
describe - no buttons operate but the K2 displays the frequency.
Check to see if your K2 is somehow stuck in transmit. The
easiest way is to check the state of the 8R and 8T voltages.
You can checkby measuring the DC voltage at the anodes of D6 and
D7. During receive, the voltage at D6 anode should be about 8
volts and the voltage at D7 should be near zero volts. If the
K2 is 'stuck in transmit', those voltages will be reversed.
If your K2 is indeed 'stuck in transmit', try removing the key
plug and the microphone - if something external is creating that
transmit condition, it should be OK with those cables unplugged.
73,
Don W3FPR
Jean-François Ménard wrote:
Hi everybody,
I have my first major trouble since my building experience back
in 2004. Now, everytime i power up my K2, I can see ELECRAFT
and then the frequency..... but everything is frozen
after...... still get the frequency displayed, but no button,
no function work. I also tried to reset the K2 to the factory
default by holding 4-5-6 buttons..... Got the 201 message then
back to the ELECRAFT and the frequency..... but still frozen !!!!
Is it possible the the control board PIC got a static discharge
or something like this !?!?!?!
============================
De Jean-François Ménard / VA2SS
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