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My SL-70 findings

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recapen(at)earthlink.net
Guest

Posted: Mon Nov 12, 2007 5:52 am Post subject: My SL-70 findings

Reposted from other lists - hopefully to elicit Bob N's comments!



Here's what I've done/found:



Upon start-up the SL-70 says TEST and FAIL in the two display windows.

If I turn the little knob on the right - it goes to the specific tests individually - all PASS except for SYN, RECV, and TRAN

Took antenna direct to the back of the unit (down to the first piece of coax) with a 5.5" aluminum disk as a ground plane.

       No change

       Measured continuity of the first piece of coax

       Open from center to shield

       Initial resistance of center conductor goes to zero shortly

       Initial resistance of shield does not go to zero but remains very low

The Transponder did not come alive - although it still continues to pass encoder info to the GPS



Here's what I think:



The radio portion of the unit is hosed and the box needs to go in for repair - off to call GarminAT repair.

The first antenna coupling (in the back of the unit's tray) and the first chunk of cable attached thereto is where I'll start troubleshooting the resistance problem.



Here's where I need comments:

RG400 shield resistance - I think it should go to zero just like the center conductor.

The first pair of connectors appear to be silver plated - and the plating appears to be oxidized - I would think that inserting and reseating the connector should (but shouldn't need to) renew the connection.

This is the same tray connector (I think) that has been recently mentioned on this list.



Thanks in advance,

Ralph Capen

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chasb(at)satx.rr.com
Guest

Posted: Tue Nov 13, 2007 9:41 am Post subject: My SL-70 findings

My SL-70 does the same thing. However, I find that if I turn the  

transponder off, wait a few seconds and then turn it back on, it goes  

through its "TEST" phase and works normally. I think the FAIL mode is  

triggered by a low voltage situation which occurs during engine  

start. I put it on my checklist to turn the transponder "OFF" before  

start. Once the alternator is on line, I turn the transponder "ON"  

and rarely have problems.



Charlie Brame

RV-6A  N11CB

San Antonio



------------------------------------------------------



 	  Quote: 	
		   Time: 05:52:24 AM PST US

 From: "Ralph E. Capen" <recapen(at)earthlink.net>

 Subject: My SL-70 findings

 Reposted from other lists - hopefully to elicit Bob N's comments!



 Here's what I've done/found:



 Upon start-up the SL-70 says TEST and FAIL in the two display windows.

 If I turn the little knob on the right - it goes to the specific  

 tests individually

 - all PASS except for SYN, RECV, and TRAN

 Took antenna direct to the back of the unit (down to the first  

 piece of coax) with

 a 5.5" aluminum disk as a ground plane.

        No change

        Measured continuity of the first piece of coax

        Open from center to shield

        Initial resistance of center conductor goes to zero shortly

        Initial resistance of shield does not go to zero but remains  

 very low

 The Transponder did not come alive - although it still continues to  

 pass encoder

 info to the GPS



 Here's what I think:



 The radio portion of the unit is hosed and the box needs to go in  

 for repair -

 off to call GarminAT repair.

 The first antenna coupling (in the back of the unit's tray) and the  

 first chunk

 of cable attached thereto is where I'll start troubleshooting the  

 resistance

 problem.



 Here's where I need comments:

 RG400 shield resistance - I think it should go to zero just like  

 the center conductor.

 The first pair of connectors appear to be silver plated - and the  

 plating appears

 to be oxidized - I would think that inserting and reseating the  

 connector should

 (but shouldn't need to) renew the connection.

 This is the same tray connector (I think) that has been recently  

 mentioned on this

 list.



 Thanks in advance,

 Ralph Capen

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recapen(at)earthlink.net
Guest

Posted: Tue Nov 13, 2007 10:07 am Post subject: My SL-70 findings

Charlie,



Thanks for the response....I'm still doing ground testing - haven't got the big fan up front running yet.  I have a regulated power supply feeding my PC680 battery set up for 13.5VDC.  I've also called GarminAT repair - they said to chase down the resistance in the antenna coax first.



When yours fails, does it still process altitude data to your GPS?  Have you tried turning the inner knob to see which subtest invoked the failure mode?



Just curious to see how it acts overall.



Thanks,

Ralph



--

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