[K2] voltage/current sensing K2 SN 4277

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[K2] voltage/current sensing K2 SN 4277

Karl Erb
Display now reads E00.7 i0.06 and low batt following my poking around inside.  Following guidance in the archives I measured (RX mode — TX display readings of swr, pwr seem ok)

D10 anode 13.89,  cathode 13.69 volts
Pins 2 and 3 of xxx 13.65 and 13.65
R9 voltages 13.67 and 2.62
R8 voltages  13.65 and 13.65
U3 voltages (1) 13.57 transitioning to 0 after 1 sec; (2) 13.65; (3) 13.61 transitioning to 0;  (4) 0; (5) 2.61; (6)2.66; (7)2.66; (8) 13.61
U6 pin 5    2.66V

Probing for suggestions for what to measure next (or advice to go ahead and replace U3 and/or U6 or something else)

Tnx for any help,
Karl W3BF
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Re: [K2] voltage/current sensing K2 SN 4277

Don Wilhelm-4
Karl,

The voltages at U3B (pins 5, 6, and 7) are correct.  Check to see if the
voltage at U6 pin 5 is the same as at U3 pin 7 - it should be.
In this case, the fact that the display indicates a low voltage says
either that the trace between U3 pin 1 and U6 pin 5 is broken, or that
the U6 pin 5 input is faulty.

As for the display of current part, either Q11 is misbehaving or there
is something wrong with R7 (check for solder bridges).
That may be correct if part of the receiver is not functioning.  The
normal current draw is 0.240 to 0.270 amps dependent on the options
installed.

You did not say what your "poking around inside" consisted of.  If you
induced static charge on some of the pins of U6 that could be the cause
- OTOH, if you were soldering, look for solder in places where it should
not be (solder bridge).

73,
Don W3FPR

On 3/26/2015 5:25 PM, Karl Erb wrote:

> Display now reads E00.7 i0.06 and low batt following my poking around inside.  Following guidance in the archives I measured (RX mode — TX display readings of swr, pwr seem ok)
>
> D10 anode 13.89,  cathode 13.69 volts
> Pins 2 and 3 of xxx 13.65 and 13.65
> R9 voltages 13.67 and 2.62
> R8 voltages  13.65 and 13.65
> U3 voltages (1) 13.57 transitioning to 0 after 1 sec; (2) 13.65; (3) 13.61 transitioning to 0;  (4) 0; (5) 2.61; (6)2.66; (7)2.66; (8) 13.61
> U6 pin 5    2.66V
>
>

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Re: [K2] voltage/current sensing K2 SN 4277

Bill Frantz
FWIW, I just found a 2mm long piece of wire clipped from a
component lead shorting my current project. Look carefully.

73 Bill AE6JV

On 3/26/15 at 3:16 PM, [hidden email] (Don Wilhelm) wrote:

>You did not say what your "poking around inside" consisted of.  
>If you induced static charge on some of the pins of U6 that
>could be the cause - OTOH, if you were soldering, look for
>solder in places where it should not be (solder bridge).

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Bill Frantz        | Re: Hardware Management Modes: | Periwinkle
(408)356-8506      | If there's a mode, there's a   | 16345
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www.pwpconsult.com | failure mode. - Jerry Leichter | Los Gatos,
CA 95032

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