[Elecraft] [K3] KIO3 serial port replacement or repair?

[Johnny Siu]

Hello Bill,

How can I know whether the KIO3 in my K3 needs modification?  I would like to 
take this chance to get the modification while I place my order for Elecraft 
gears very soon.
 TNX & 73, 


Johnny VR2XMC 




________________________________
寄件人﹕ Bill W4ZV <btippett at alum.mit.edu>
收件人﹕ elecraft at mailman.qth.net
傳送日期﹕ 2011/4/14 (四) 8:33:13 PM
主題： Re: [Elecraft] [K3] KIO3 serial port replacement or repair?


DM4iM wrote:
> 
> i believe i zapped KIO3.
> 
> 2 Symptoms:
> I can't use the DTR and RTS lines for cw keying via my logging
> software.
> ACC will not switch on the external Transverter.
> 
> Any idea how to repair the board?
> 
> On the Elecraft K3 parts and Mods kits page i see REMIOUPGD, is this the 
> device i need for replacement?
> 

No.  You most likely blew U1 on the KIO3 Main board.  I've now done this 3
times and twice just in the past 2 months on a relatively new #4717!  I'm
told that there is a more rugged design in current production and a mod for
older units should be forthcoming soon.

Here are the instructions from Elecraft to check U1:

"With the serial cable removed from the back of the K3, please check to see
if there is at least -5VDC at U1 pin 8 on the KIO3 main board, or at the
gold plated hole which is right next to pin 8 (bottom left side of U1, as
you face the front of the rig. -7VDC or more is normal.  Also touch U1 to
see if it feels hot or warm, or if it looks to be visibly damaged."

Remove the top cover and you can measure U1 pin 8 with the KIO3 in place. 
It's the lower left pin of U1 (which is near the top of the Main KIO3 board)
as you're looking from the front of the rig (not facing the front as the
above note implies).

73,  Bill  W4ZV