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[wxsig] Help with T-238 failure

Sct599 at aol.com Sct599 at aol.com
Wed Jun 29 20:10:02 UTC 2005

Hi John:
Thank you for the response. 
LCD: When I initially found the unit after the failure, the display had  
random unintelligible blocks of pixels. These pixels would change in response to  
pushing the "Select" button. After subsequent power ups, the display is blank 
of  any pixels. The back light remains functional. With it showing the random 
pixels  initially indicate that it may have survived the event?
Crystals: I will check these as soon as I can and report back. Believe it  or 
not, my scope is only a 5Mhz!
PC port: I had thought about doing this but did not since there was no  
"heartbeat" LED activity. Heartbeat LED checked out OK. Should I give it a try  
Thanks again,
In a message dated 6/29/2005 10:43:26 A.M. Mountain Daylight Time,  
w9ddd at tapr.org writes:

Any  indication that the LCD module survived?  For some reason that and the  
crystal modules would be the first suspects on my list.  You should  be 
able to talk to the unit without the LCD though via the PC port.   

I'd start by verifying the oscillator works with either a scope or  logic 
probe that's good to 32MHz.  Nothing happens with the 32MHz  clock working.

On Wed, 29 Jun 2005 Sct599 at aol.com wrote:

>  Hello Group:
> I am looking for any input you all may be  able to provide concerning a  
> failure with my T-238 (original  model).
> Found that the U5 voltage regulator had failed  putting approx 11 volts on  
> the 5 volt buss. Replaced U5 and no  indication of unit coming back to 
> Performed the "Power up  and initial testing" procedure and all appears to 
be OK.  
> Is it  safe to assume that the U3 microprocessor and possibly all 
> powered by the 5 volt buss have been destroyed?  If so, is there  any hope  
> repairing this unit?
>  73,
> Scott - NØLNE
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John,  W9DDD

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