[Elecraft] Woops something blew !!

[Phil Wheeler]

Brian,

Looks like an ohmeter could verify if the trace is cut -- and if others 
are intact..

Given Q2 voltage is an indicator, I would check the voltages at Q4, too.

73, Phil

Brian H. wrote:

>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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