[Elecraft] KX1 appears dead after KXB3080 PCB installed... ...Help please!

[Don Wilhelm]

Shawn,

KX1 display problems are usually caused by U1, so your suspicions are on 
target.
Before doing anything else, be certain U1 is properly seated in its 
socket.  You should have almost all of the narrow part of the pins 
inserted in the socket.  If that is not the case, press it in - it does 
take a bit of pressure to seat U1.

OTOH, if U1 is already fully seated, you should request a replacement 
for parts at elecraft.com.

On the voltages you find out of bounds, pins 6 and 7 are inputs to U1 - 
and that means something other than U1 is the cause for the voltage 
being abnormal.  In particular, the pin 6 voltage is sourced at U5 pin 
2.  Check that pin - if the voltage there is 1.4 volts, but is zero at 
U1 pin 6, check your soldering.

The soldering on the KX1 is more critical than most of the other 
Elecraft kits due to the high density of parts.  Your solder connections 
should look like the figures in the Soldering Tutorial at the Elecraft 
Builder's Resource page.

If soldering is the problem, it would be wise to wick away any excess 
solder and re-solder with a 750 deg F iron making certain the solder 
flows on each and every solder pad.

73,
Don W3FPR

73,
Don W3FPR

Shawn Morrow wrote:
> I have been using my KX1 for the past year or so.  This past weekend I
> decided to install the KXB3080 option.  Performing the checkout step after
> the KXB3080 PCB install failed normal operation!  Nothing works.  My KX1 now
> appears to be mostly dead.  :-0
>
> I am hoping the collective wisdom of the list can confirm or suggest other
> possibilities I should check out to try to revive my KX1.  The other thing I
> fear is multiple component failures.  Please help!  I am anxious to return
> to the air!  (Believe it or not my KX is my station!)
>
> Here is the run down:
>
> The mods to the KX1 PCB (Part 1) went well and passed all the re-alignment
> checks.
>
> I installed the KXB3080 PCB fairly easily.  (I did have some problems
> removing solder from the plated through hole for L7 near R2.  Ultimately I
> also got solder in the adjacent G through hole as well.  I eventually got
> these cleared.)
>
> Upon performing the check out step towards the end of the this section (Part
> II in the KXB3080 manual) I experienced the following:
>
> 	Current drain 36mA @ 13V - OK.
> 	LED lit up momentarily, 1 or 2 segments missing, then went dark. (!!)
>
> Subsequent attempts to power up go like this:
> 	NO LED
> 	NO Relay Clicks at power up
> 	Current: 36mA @ 13V
> 	Buttons - unresponsive
> 	White Noise from earphones, volume works
> 	RF Gain and Filter have no affect on the audio
> 	(I did not check RF out.)
>
> I double re-checked the install.  No anomalies were noted.
>
> I opened up the trouble shooting section of the KX1 Manual:
>
> 	Section 00 - all ok
>
> 	Section 20 - all regulators are right on: 6V, 5V, 2.7V
>
> 	Section 26 - U1 Voltage Levels (w/i 10%) Measured @ 13V
>
>           Pin    Spec  Meas      Pin     Spec    Meas
>            1     5.0   5.0        15       0       0
>            2     5.0   5.0        16       0       0
>            3     4.6   5.0        17       0       0
>            4     4.9   5.0        18       0       0
>            5     4.9   5.0        19       0       0
>            6     3.4   4.3 <<     20     5.0     5.0
>            7     1.4     0 <<     21     5.0       0 <<
>            8       0     0        22     5.0     4.7
>            9      .8    .8        23     4.9     4.7
>           10      .9    .9        24     5.0     4.8
>           11       0     0        25     5.0     4.8
>           12       0     0        26     4.7     4.8
>           13     5.0   5.0        27     5.0     4.8
>           14       0   5.0 <<     28     5.0     4.8
>
> Measurements marked with "<<" are outside the 10% tolerance limit!!  Is it
> fair to conclude U1 is toast!?!?
>
> At this point I think I probably "fried" U1 during the install.  Since its
> winter and pretty dry in doors I am guessing ESD got it.  This despite using
> an anti-static mat, ...and wrist strap -- *most* of the time. :(
>
> I am hoping the collective wisdom of the list can confirm or suggest other
> possibilities I should check out before replacing U1.  The other thing I
> fear is that perhaps other components were damaged in the process.
>
> What say you??
>
> Regards, Shawn Morrow
>             W4SDM
>   
>