[TechAssist] Re: CTC1777 PICTURE TOO LARGE
- From: Dennis Viereck <wa6ati@xxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Sat, 03 Nov 2001 23:26:03 -0800
I'm reading all the threads of this and other technical assistance questions and
one thing is strangely evident. I do not see the authors of these questions
offering any voltages.
Doesn't anyone use a DVM anymore?
Not once have I read in this thread any mention of voltages to check. Or anyone
asking about voltages. Just parts to replace......
I would like to be the first to ask.
What is the voltage at the Cathode of that "Big diode"? (This is the pincushion
modulator diode. CR4402)
What is the voltage on Q4851 the pin output transistor?
When in the tech menu, does parameter 3 or 4 have any effect on the symptom?
Does the signal amplitude change on U1001(19)? (This is the E/W pincushion
output voltage) It will have a 16.6 ms parabolic waveform at about 1.5 volts
peak to peak. It's amplitude will vary with the value of parameter 4.
Does the DC voltage vary at U1001(19)? It should be about 2.5 volts. The DC
level will vary with the value of parameter 3.
If U1001(19) does not vary with the parameter adjustment you may have a system
control problem or a failure in the T2 chip.
If more help is needed we'll need a complete model or chassis number.
Dennis
Robert Herring wrote:
> Lloyd see if you have c4407, c4403, c4402
> one of these is bad most likely c4407
> replace any diodes that may be parrallel with these caps
> ----- Original Message -----
> From: "lloyd wright" <mrwright21@xxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>; <listbot@xxxxxxxxxxxxxxx>
> Sent: Wednesday, November 07, 2001 1:07 PM
> Subject: [TechAssist] CTC1777 PICTURE TOO LARGE
>
> > PICTURE BOWS ON BOTH SIDES BUT STILL FILL OUT ALL THE TOO LARGE FOR THE
> > SCREEN CANOT SEE CHANEL # CCHAGE BIG DIODE IN PINCCSHION ECG 577 NO
> > CHANGE CHANGE EPROM OUTPUT TRANSISTOR CHANGE REGULATOR IC
> > CHECKPINCHUSION BROAD COULD NOT FIND NOTHING WORNG
> >
> > --------------------------------------------------------------------------
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