[Elecraft] Re: Help, I think I've killed my K1

[John Webster]

Elecrafters:

A big thank you to all those who helped with the diagnosis of the 
initial problem (blown FP 6v regulator, due to high RF field from
another rig's antenna matching unit while the K1 was on standby), 
and all the helpful suggestions made.  Unfortunately, this is not
the end of the story.

PART II  [Rather long]

A locally purchased NTE988 regulator (6.2v rather than 6v) 
brought the rig back to life, but with erratic MCU activity.

Earlier this week I received the proper replacement part from 
Elecraft (at no cost to me, aren't these guys great!) and had
high hopes of a fully functioning rig in time for the EQP this
weekend.  However, while some of the problems that were
present with the NTE988 have cleared up, things are still
not right.  Here are my findings:

Functional Anomalies--
1. While the K1 will switch on normally, and the RX seems
to work well (freq readout is accurate when checked against
another rig), any attempt to change bands will cause the K1
to go into a state where the RIT and ATT lights will flash
alternately, indefinitely.  If the rig is switched off and then on
again, it will be apparent that the band switch was made.

2. The Offset pot (RIT/XIT) works all the time, i.e. it always
varies the frequency on both receive and transmit, regardless
of whether RIT or XIT have been switched on or not.  The 
flashing decimal point does NOT appear unless the RIT is
switched on.  The RIT pushbutton and RIT/XIT LED works 
as expected.  This is very odd to me.

3. All menu functions and FP pushbuttons work normally, but
there is a distinct buzzing sound while pushbuttons are pressed,
at least clearly audible when using headphones, less so on the
speaker.  [This excludes band changes as per 1.]

4. The transmitter works.  A strong signal (clean sounding) can
be heard on another receiver.  The sidetone signal sounds 
clean, but there are unusual artifacts that one can hear in the K1's
headphones while sending.  Message buffers work OK

5. The built-in voltmeter, S-meter, and power-out meter does
not read correctly.  The internal battery pack is at 10.2 volts,
but the LCD reads 14.2 volts when on voltmeter setting.  The
bar graph S-meter reads significantly lower (a signal that is 
clearly S9 or stronger reads only one or two segments).  The
power-out segment meter reads full scale (6 segments) when
the power out setting is set to 2 watts.  Clearly these readings
are wrong.

6. The ATU will not function correctly.  It will not find a match
on an antenna that it has always matched without difficulty before.
This is probably due to problems noted in 5.

Voltage Measurements:
All the readings given below were with the internal battery pack
at 10 volts.  I chose to stay with the battery pack since I suspect
something is causing an excessive drain on the 6v regulator(s) and
did not want to risk further damage.  I used a DMM to make the
following readings.  I removed the filter board and ATU to make
the voltage readings.  Thus, as expected, on power up the LCD 
reads E27.

1. The new replacement 6v regulator ZR78L06C from Elecraft
is only putting out 4.3 volts.  Thus FP U1 pin 40 is 4.3v as are all
other pins on FP U1/2/3 that expect 6v.

2. The pins on FP U1 that expect 3v are reading 2.3v.

3. A surprise to me is that the RF board 6v regulator (also a
ZR78L06C,  6B line) is also showing only 4.6 volts, e.g.
on RF U2 pin 6.  [But the RX works OK?]

4. The 8v regulator RF board U5 is OK.  Output voltage
is 8.4volts.

5. Here are some other voltage readings: [Not sure these are
a problem given lower supply voltage]
        RF U4 pin 6 should be 6.6v but reads 4.89v
        RF U4 pin 7 is supply voltage, in my case reads 9.96v
            (given the NiMh battery pack at 10.2 volts, OK I think)
        RF U4 pin 8 should be 6.8v, but reads 5.11v

Can anyone make sense of these results?  Again any help would
be greatly appreciated.  Is it the MCU that has gone?  Or some
other suspect component?  Should my next step be to pull the 
MCU chip FP U1 and take readings again?

Thanks in advance,

73, John N6JW