[TechAssist] Re: RCA p52929
- From: Dennis Viereck <wa6ati@xxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Sun, 11 Nov 2001 22:28:37 -0800
I would say that is NOT normal. Typically the human finger can handle 120
degrees F. Much higher then that becomes uncomfortable to the touch. This is
the point where silicon devices start having reliability problem and unstable.
I might go as far as to say that is a "big red flag" you might want to
investigate. U17501 should not be that hot.
Dennis
Jonas Miglinas wrote:
> Thanks Dennis for the advice and the tip, this wouldn't be so bad if it
> wasn't so damn intermittent.One thing I did notice, the two ic's inside the
> tuner can get pretty warm, especially U17501.(can't hold finger on it after
> ~10 seconds) Is this normal? Never had problem with the tuner in any
> manner.
> Hope you have a quiet sunday.
> Regards Jonas
> ----- Original Message -----
> From: "Dennis Viereck" <wa6ati@xxxxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Sunday, November 11, 2001 10:08 AM
> Subject: [TechAssist] Re: RCA p52929
>
> >
> > I have had several peripherals cause the data or clock line to short to
> ground.
> > In this method you can now isolate all peripherals from the Run data/clock
> > lines. The Digicon, PIP, Combfilter, T4 chip, AV switch, ... anything that
> > attaches to the buss can cause this problem. The best thing is to isolate
> > everything that is easy to isolate first. But remember both line must be
> high as
> > long as you have jw12410 removed and U13101(3 & 4) isolated.
> >
> > Good luck
> >
> > Dennis
> >
> > ps; My last problem child like this one was the PIP module. I had a
> surface
> > mounted capacitor leaky causing the data line to be sitting at 2.2 volts.
> >
> > Jones Miglinas wrote:
> >
> > > Hi Dennis,
> > > I cut 12410 and got 12 + 5 volts back, set did not turn on. Floated
> pins
> > > 3+4 and got 5v at pin 4, missing 5v at pin three. Started to trace and
> > > voltage would come back. Bending , hitting, and freezing board doesn't
> seem
> > > to affect the 5v in one way or another. I checked the K20 area and it
> seems
> > > solid. Have you ever had missing data/clock due to bad convergence
> board?
> > > Any and all suggestions would be greatly appreciated.
> > > Regards Jonas
> > > ----- Original Message -----
> > > From: "Dennis Viereck" <wa6ati@xxxxxxxxxxxxxx>
> > > To: <techassist@xxxxxxxxxxxxx>
> > > Sent: Wednesday, November 07, 2001 12:33 AM
> > > Subject: [TechAssist] Re: RCA p52929
> > >
> > > >
> > > > Error code 16 means, "RUN buss stuck to a Logic low"
> > > >
> > > > To check that circuit, carefully cut the jumper JW12410 located next
> to
> > > the square metal shield that surrounds the Main Microprocessor.
> > > > By cutting this jumper you have just turned on the U14701 the 5 and 12
> > > volt regulator.
> > > > Be sure you have these voltages. If these are OK then try to turn on
> the
> > > TV.
> > > >
> > > > If it turns on test play the set a while. See if it operates
> correctly. If
> > > so you may have to perform an upgrade on the F2PIP reset circuit.
> > > >
> > > > If It still will not turn on then float the pins on U13101(3 & 4) and
> > > measure the voltage on the foil pads. THEY BOTH MUST BE 5 VOLTS!. If not
> > > you'll have to trace these lines and isolate them until you get the 5
> volts
> > > back. Note: If someone has previously worked on the tuner then I would
> start
> > > there and check coordinates K20. This is an area where the data and
> clock
> > > line make a 90 degree turn out from under the shield. This trace is so
> close
> > > to the shield it sometimes gets touched with solder in the process of
> > > reattaching the shields for the tuner.
> > > >
> > > > Let me know if you need any other information on this unit.
> > > >
> > > > Denins
> > > >
> > > > Jonas Miglinas wrote:
> > > >
> > > > > Hi all,
> > > > > I have a ctc195 chassis that is less than a year old that will shut
> off
> > > and won't start (not even a click) and will stay off from 5 minutes to
> 5hrs
> > > or so. this symptom can occur from 1 to two times a day to 1 time a
> week.
> > > Chipper shows error code "16" ,run or data lines clamped to logic "0".I
> do
> > > get Stnby voltages of 16 + 33 + 140+ -12 . Whats missing are the +5 and
> +12
> > > from U14701.Pressing power, pin 19 of u13101 tries to go high but only
> > > reches 1.3v The outputs of U14701 at Stnby ~ 1v at power on may reach
> ~3v.
> > > I've changed U14701, U14101, Q14101, U3101, and the T4 chip. Also
> checked
> > > y13101 and its associated circuitry. Substituted Gemstar fom another
> like
> > > model and that checked out ok.
> > > > > Any suggestions would be greatly appreciated.
> > > > > Regards Jonas
> > > > >
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