[Elecraft] Woops something blew !!

[Phil Wheeler]

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?

Sounds like this may be a tough nut :-(

73, Phil

Brian H. wrote:

>OK, more info on this.
>
>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 ??
>
>Thanks
>Brian
>
>
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