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[wxsig] Crashing and random characters

Ken Brown Ken.A.Brown at noaa.gov
Mon Jun 30 14:10:27 UTC 2008


A couple of years ago someone posted a message about this subject and
he said he replaced the voltage regulators with drop in replacement
TI switching regulators.  I have done the same thing and my original
T-238s are now quite stable.  They are three terminal drop in
replacements for the 7805 regulators. They cost about $10 at the time.
Unfortunately I don't have the part number at hand here but could look
it up this evening.  I got them from Mouser.

Ken

Guy Story KC5GOI wrote:
> William Beals wrote:
>> Guy:
>>
>> Ouch, that doesn't sound good.  It also doesn't sound familiar
>> unfortunately.
>>
>> You definitely want the 1.15.8 firmware, it is a lot better and more stable
>> than 1.15.4.
>>
>> Any chance the voltage regulator is overheating?  It can happen reliably if
>> your incoming supply is much over 12V and your backlight is on.  For a
>> lightly loaded and unregulated wall wart, that voltage can easily get up to
>> 14 or more volts.  The regulator handles it for a while, but then starts
>> going into thermal shutdown which isn't a graceful on/off shutdown.
>>
>> will
>>
>>
>>   
> 
> Will, the heat sink for the voltage regulator is getting too hot to 
> touch.  I do not require the back light.  I will check the schematic 
> tonight for the trace the backlight is on and cut the trace.  I remember 
> we had to do that on the original kit year ago due to a short on that 
> trace.  The power supply is putting about 13.3, and I am running 4 
> instruments.
> 
> Thanks.
> 
> Guy
> 
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