[TechAssist] RCA PTK195B, mostly dead.

This set works sometimes, but most times not.  When the set does work,
it will work for a minute and then just shuts off by itself and will not
come on.  I have the SM on CD rom and I am following the trouble
shooting procedure.  I found that when I monitor pin 19 of U13101
(microprocessor) and press the power button, pin 19 does not go high as
it is supposed to.  The micro has 5 volts going to pins 16, 29, 32 and
51.  Pins 3 and 20 of U16201 are missing the required 7.5 volts.  After
that the troubleshooting flowchart tells me to repair the defective P/S
source.  So I traced the missing voltage back to U14701, a dual voltage
regulator.  Pin 6 is missing 12 volts and pin 7 is missing 5 volts.  Pin
1 and 2 both have 18-20 volts which is good.  Pins 3 and 5 are supposed
to have the 5 volts from pin 19 of the micro when the set is on.  But of
course there is no 5 volts coming from the micro.  The set must be going
into shutdown.  What can I check next?  Thanks.   

Kevin Wilks
Kevin's TV & Video Repair
Penticton BC Canada
kevintv@xxxxxxx 
 



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