[TechAssist] Re: RCA F27701BK CTC169CA6 Primary voltages too high
- From: "Leonard G. Caillouet" <lcaillo@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Wed, 14 May 2003 10:53:32 -0400
Monitor the clollector of Q4107 for 15vpp H-pulse (- going) from FBT and
pin 2 of U4101 for 3 vpp H-pulse (+ going). This is the input to the
regulator for the duty cycle of the chopper.
Check the values of the resistors R4114, 15, 16, 18. This is the network
that supplies the B+ sample to the error amp q4105.
This info comes from Bob Rose's book on RCA TV servicing, BTW, I'm not that
smart a guy... It is a good source for an overview of many RCA chassis and
their problems that will often point you in the right direction as a start.
This circuit can be tough to troubleshoot without a good reference if it is
not the routine problems like the caps or reg IC.
Leonard G. Caillouet
Service Manager
Electronics World
Gainesville, FL
352-332-5608
352-332-5668 (fax)
Leonard G. Caillouet
Service Manager
Electronics World
Gainesville, FL
352-332-5608
352-332-5668 (fax)
----- Original Message -----
From: "Neil Bowman" <tvdoctors@xxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Tuesday, May 13, 2003 11:46 AM
Subject: [TechAssist] RCA F27701BK CTC169CA6 Primary voltages too high
>
> I just about checked all components in the power supply and even changed
the regulator Ic but still I get excessive primary voltages, ie; B+ 200
volts, Cr4118 around 22 volts. Power supply will shut down within 5 seconds
after plugged in because of overvoltage. I monitored these voltages when
plug was engaged before shutdown. Any tips for this symptom, Thanks Neil
> TV Doctors
> Monroe,Wa
>
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