From: Garey Barrell 
Subject: Re: [drakelist] TR7 Display Problem


Garey Barrell  made an utterence to the drakelist gang
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Eric -

More likely the exposed wire was broken, as once installed there is 
clearance.  Just tight getting the board in or out, and several sharp 
edges of surrounding aluminum shields to navigate past.

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
http://hr99.home.mindspring.com/R-4C_Servicez/>



Eric Webner wrote:

> Thanks for the reply Garey,
>  
> The end result is the choke shorting out against the shield, possibly.
>  
> Eric
>
>
> */Garey Barrell /* wrote:
>
>
>     Garey Barrell made an utterence to the drakelist gang
>     ----------------------------------------------------------------------
>     Eric -
>
>     From what Bud said, I got the impression that the problem was
>     caused by
>     "scraping" the exposed wire of the RFC against the shield, other
>     board,
>     whatever in removing or inserting the VCO board. Those slots are
>     small,
>     and there are lots of protuberances and sharp edges to interfere.
>     That
>     choke is right on the edge of the board, and does stick up pretty
>     high.
>
>     73, Garey - K4OAH
>     Atlanta
>
>     Drake C-Line Service Manual
>
>
>
>
>     Eric Webner wrote:
>
>     >
>     > Bud,
>     >
>     > How did you guys determine that it was the choke. Did the core
>     crack
>     > from physical damage, or did it go intermittant or , , , ?
>     >
>     > 73,
>     >
>     > Eric KA8FAN
>     >
>     > */Garey Barrell /* wrote:
>     >
>     >
>     > Garey Barrell made an utterence to the drakelist gang
>     >
>     ----------------------------------------------------------------------
>     > Wow! Talk about obscure....
>     >
>     > The ONLY thing this choke does is filter the 24V supply to the PLL
>     > Loop
>     > amplifier chip, so the VCO was yanked way out of it's
"normal"
>     range.
>     > I _TOLD_ you we needed to measure the loop error voltage....! :-)
>     > Yeah, right. At least now we know it really WILL go that high.
>     >
>     > Thanks for the feedback!
>     >
>     > 73, Garey - K4OAH
>     > Atlanta
>     >
>     > Drake C-Line Service Manual
>     >
>     >
>     >
>     >
>     > sebdesn wrote:
>     >
>     > >"sebdesn" made an utterence to the drakelist gang
>     >
>     >----------------------------------------------------------------------
>     > >Well finally,,,! ,
>     > >
>     > >Wanted to post the resolutio! n for the archives in case anyone
>     > else has this
>     > >problem.
>     > >Many thanks to Bill Frost who had the final answer, and Garey
>     > Barrell, and
>     > >Peter VE3AX for some good troubleshooting suggestions.
>     > > The rig showed 96800.0 on powerup(20m and below) and drifted down
>     > >slightly. VFO did not change anything. Counter worked properly in
>     > "ext"mode.
>     > >All voltages from p/s board were OK. 10R and 10T on main board
>     > were ok and
>     > >switched properly xmit/ rcv. All oscillator freqs were there and
>     > right on.
>     > > The problem was choke RFC508 which is in the 24v circuit to
>     the VCO
>     > >board.It is on the VCO board and is in a position that could be
>     > easily
>     > >damaged inserting the board. Replaced that, fired things up, and
>     > all is
>     > >well. Will align and put on the air..
>     > > Again tha! nks to all who helped. This is a great list and in my
>     > case, a
>     > >real lifesaver!!!
>     > >
>     > >73,de Bud WØHG
>
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On Behalf of Garey Barrell 
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