[Elecraft] Woops something blew !!

[Brian H.]

Hi, Yes , basically the only connection to the top of the case is the
speaker cable, ie, the battery, IO, Tuner are all out of the picture
(although I did not change any menu settings). Also, yes the noise in the
speaker and the "changing" voltages do occur slowly - perhaps 2-3 seconds
for the 8V to drop to 0.6V !!

I did continue tracking voltages and found that the voltages on the E,B,C of
Q1 are correct, but on the collector of Q2 ( the pin furthest away from the
top of the control board) I see an initial 8V that drops to 0.6V after a few
seconds. Q1 and Q2 are both on the control board.

Recall I just added the AF and IO options. Everything appeared to work OK
after I added the AF, the problems started when I added the IO option and
connected to a computer - does anyone know what would happen if I did not
correctly cut the track on my rev A board as required by the IO instructions
? I think I did cut the track thru but it is very hard to tell, also I
suppose if the multi layer board is very thin the I could have shorted thru
to the next layer. Is there any pins I can measure on U6 to verify ?

I have copied all the detail from previous messages in order to list
everything in 1 message.

Thanks for all the help,
Brian

***********************************

> Brian,
>
> I don't recall your test config.  Am I correct in thinking that the KIO2
> is *not* in when you get the following results?
>
> In
>
> >4) D2 at the far end of the RF board initially reads 8/7.5V (
Cathode/Anode) and then drops to .6/.1 V after 6 seconds !!
> >5) Rechecking the 8V regulator shows a constant 8V over time
> >6) Pin 21 of connector P2 ( main connector from the control board to the
RF board shows 8V DROPPING to 0.6V !!
> >
>
> Are these drops gradually (R-C time constant sort of thing) or like a
> step?  If the latter, I would look for something shorting or openning up
> due to a thermal condition..  BTW -- what page of the ckt dgm is D2 on
> (I'm not finding it), and are you measuring the 8V regulator voltage at
> that component or elsewhere?


************* Second message ****************


First, thanks everyone who sent me some ideas. I did some tracing of the
voltages around the different boards and here's what I found;

1) As I said in my first message the noise in the speaker disappears after
about 6 seconds. The LCD never lights up.
2) I totally disconnected the battery and connected to the AC and still have
the same problem.
3) The 8V and 5V regulators are OK
4) D2 at the far end of the RF board initially reads 8/7.5V ( Cathode/Anode)
and then drops to .6/.1 V after 6 seconds !!
5) Rechecking the 8V regulator shows a constant 8V over time
6) Pin 21 of connector P2 ( main connector from the control board to the RF
board shows 8V DROPPING to 0.6V !!

Obviously it looks like something along the lines of a capacitor (RC time
constant ??) is causing a problem but does anyone have ideas ??


************* First message ****************

Hi, I just installed the KIO2 kit in my K2 ( includes the Tuner, SSB, AF,
160 and battery). Initially everything worked well for a few minutes then I
started to remotely "Tune" the rig and got a Lo Power message. I turned up
power to about 8W and still got the same message .. then everything died !!
No LCD readout, no relays clicking, no signal nothing except some noise thru
the speaker which does appear to be affected by the volume control. I tried
to "remove" the IO board but that doesn't appear to make any difference.
Anyone have any idea's ? My debugging skills are rather limited ( the K2 was
my first ever kit !!).

Thanks
Brian, KD7Z Serial Number 301

Need to get this sorted out ASAP, the K2 100W PA is in the mail (hopefully)
!!

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