[TechAssist] Westinghouse TV, Model WTV12505, Shutdown

  • From: gulftech@xxxxxxxx
  • To: techassist@xxxxxxxxxxxxx
  • Date: Tue, 13 Nov 2001 11:01:45 -0600

Friends,

This set goes into shutdown.  Trouble is, usually plays four three or
four days before failing.  The set will then not turn on unless unplugged
first.

The ONLY thing I know of that will cause this is the HV shutdown circuit.
 For those without Sams 4068,  the circuit is simple.  Voltage from the
flyback is rectified by D405, filtered by C414, and sent through voltage
divider R414 & R415.  The voltage at the junction of R414-R415 is fed
through 9.1V zener D401 to p24 of the signal processor.  There is a
resistor RC 401 & cap C401 from p24 to ground.  If the voltage at that
junction exceeds 9.1, the unit will shut down.

Problem is the set is so darned intermittent.  I monitored the voltage
applied to the zener for hours.  Never found it rise above 7.4 volts.  I
have checked all components listed above, but changed none.

This set is driving me crazy.  Any suggestions?

Thanks,


Ken Smith
Gulf Technical Services
3034 Gulf Breeze Parkway
Gulf Breeze, FL  32561
850-934-8324 (Voice) 850-932-0819 (Fax)

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