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[wxsig] Help with T-238 failure

N5ZTW Bill n5ztw at texas.net
Sat Jul 2 23:47:56 UTC 2005


I have LCD modules also.
Bill N5ZTW
----- Original Message ----- 
From: <Sct599 at aol.com>
To: <wxsig at lists.tapr.org>
Sent: Saturday, July 02, 2005 5:08 PM
Subject: Re: [wxsig] Help with T-238 failure



John, Bill, and Will:

I got a hold of a an oscope and both of the ocillators appear to be dead.
With the good news that the semiconductors are tough, my next move will be 
to
test the LCD. I am going to try to get a local guy to allow me to connect my
LCD  module to his unit. If it checks OK, I will proceed with the 
oscillator(s)
replacement. I understand the 32Mhz crystal is primary for operation but 
what
is  the 9Mhz used for? Only reason I ask is to determine if I need to 
replace
it at  least initially.

Thank you for letting me know you have some spare components. This could
prove to very handy once I check the LCD and replace the oscillator(s). 
Should
my MPU appear to be failed, I would be happy to send it for the Freescale
folks for autopsy.

Thanks again for your support. I will report back as soon as I get the LCD
module checked out.

73,
Scott


In a message dated 7/1/2005 6:28:36 A.M. Mountain Daylight Time,
w9ddd at tapr.org writes:

Will  managed to find a 'hot spot' in London to reply to me on another
subject.  Below are his comments related to the 7805  failure.

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

On the gentlemen with the bad 5V bus, all  I can offer is that the micros
are pretty tough. I've abused a few in my  life and even though the part
was tortured way out of spec there is a  decent chance it survived. The
oscillator is clearly a concern. A quick and  dirty check for the clock is
a voltmeter in DC mode. If you see 0V or 5V  you are pretty certain things
are blown. Somewhere around 1.5V to 2.5V, at  least you stand a chance of
the clock being OK.  Only suspect the LCD  after getting the CPU heartbeat
working and the LCD still doesn't  work.

will
------------------------------
Message sent using  thumbs on a PDA.
Sent wirelessly, so recycled elecrons
are also 100%  local content.


On Thu, 30 Jun 2005, N5ZTW Bill wrote:

> I  also have spare MPU's. If it's the MPU I can try and get a failure
report
> on it. My system keeps locking up and it may be the MPU also. I'll  look 
> at
> it this weekend. I work for Freescale Semiconductor (Former  Motorola) and
> know the guys in the group that supports the chip.  (some are hams). We
> reside in the same campus so it may be worth have  them autopsied.
> Bill N5ZTW
> ----- Original Message -----
> From: "John Koster" <w9ddd at tapr.org>
> To: "TAPR Weather  Station SIG Mailing List" <wxsig at lists.tapr.org>
> Sent: Thursday,  June 30, 2005 9:19 AM
> Subject: Re: [wxsig] Help with T-238  failure
>
>
> >I have spare MPU and RS232 chips  here.  I don't for the 32MHz oscillator
> > module, since it's a  different version for T238+
> >
> > On Wed, 29 Jun 2005  Sct599 at aol.com wrote:
> >
> >>
> >> 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
> >> anyway?
> >>
>  >> Thanks again,
> >> Scott
> >>
>  >>
> >>
> >>
> >>
> >>  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
> >> life.
>  >> > 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
> >> components
> >> > powered by the 5 volt  buss have been destroyed?  If so, is there 
> >> > any
> >>  > hope
> >> in
> >> > repairing this  unit?
> >> >
> >> >  73,
> >>  > Scott - NØLNE
> >> >   _______________________________________________
> >> > wxsig  mailing  list
> >> > wxsig at lists.tapr.org
> >>  >  https://lists.tapr.org/cgi-bin/mailman/listinfo/wxsig
>  >> >
> >>
> >> --
> >>  73,
> >> John,  W9DDD
> >>
>  >>
> >>  _______________________________________________
> >> wxsig   mailing  list
> >> wxsig at lists.tapr.org
> >>  https://lists.tapr.org/cgi-bin/mailman/listinfo/wxsig
> >>
>  >>
> >>
> >>
> >>  _______________________________________________
> >> wxsig mailing  list
> >> wxsig at lists.tapr.org
> >>  https://lists.tapr.org/cgi-bin/mailman/listinfo/wxsig
> >>
>  >
> > -- 
> > 73,
> > John, W9DDD
>  >
> >
> >  _______________________________________________
> > wxsig mailing  list
> > wxsig at lists.tapr.org
> >  https://lists.tapr.org/cgi-bin/mailman/listinfo/wxsig
> >
>
>
> _______________________________________________
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> wxsig at lists.tapr.org
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>

--
73,
John,  W9DDD


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