[TechAssist] Re: Sony KP61XBR300 ---Repeat IK failure
- From: Dennis Viereck <wa6ati@xxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Sun, 13 Jan 2002 09:24:27 -0800
Damon:
Great antidote on the fix or possible fix. When you set the drives did you ever
loose the slight green raster in the at the tube? I always thought, that when in
the video input mode, and no video excitation, that each tube will be at "0" or
"near 0" beam current. With a slight green raster you have to be pulling some
beam current.
Dennis Viereck
Damon wrote:
> Thanks Dennis, your info was on target.
>
> I found the green Ik pulse on the cathode was 40vpp. Also I changed the
> setup procedure, my mistake was trying to set the screens on a signal-less
> video input to black, rather than setting the black pedestal to 175 volts
> using a scope. I find when I set that properly, I had a "slightly green-no
> picture" condition on video input. That bugged me.
>
> Anyways, when I set the pedestal to 175 Volts, my cutoff and drive
> adjustments on the Blue CRT now seem to mirror the Red and Green adjustments
> (my blue was about 60 and red/green about 30 when bad, now all are 35).
>
> Now I don't want to say this PTV is fixed yet, it has been intermittant
> since last March, but I do know that the setup on these Crts are right on
> target. The IK pulse on all 3 Crts are now 20Vpp.
>
> Thanks for the info.
>
> Damon Brunger
> damon101@xxxxxxxxxxxxxx
> Telrad Electronic Services
> Ft Wayne, IN 46815
> ----- Original Message -----
> From: "Dennis Viereck" <wa6ati@xxxxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Thursday, January 10, 2002 9:47 AM
> Subject: [TechAssist] Re: Sony KP61XBR300 ---Repeat IK failure
>
> >
> > Damon:
> > I've only had CRT's and the IK buffer transistor, which there are 1 on
> each module. When the set is in the failed condition, what amplitude does
> the IK pulse have on the cathode of each CRT, after ample time has been
> given to warm the filaments? If you suspect the blue CRT I would start
> there. Finally are you getting all three IK pulses fed back to the RGB
> processor?
> >
> > I have had problems with the CRT's where the IK pulses at the cathode were
> unusually high 45~ 55 volts peak to peak where the other two are 20~ 30
> volts peak to peak. But in the sam instance the IK feed back looked normal
> with all pulses within 10 ~ 15% of each other. Swapping that tube brought
> the IK pulse back to the 20 ~ 30 v pp.
> >
> > As for the HV block and the possibility of it causing an IK failure: I
> don't think that it would be reasonable. Any internal leakage that would
> load down the high voltage on 1 output would load down the output of the
> high voltage transformer too. This will increase in current would cause an
> over beam current shut down, not a IK error.
> >
> > Dennis Viereck
> >
> > Damon wrote:
> >
> > > Hello All,
> > >
> > > My question is : has anybody had a problem with the HV Splitter or the
> Power supply causing an IK failure to be registered?
> > >
> > > I have had a nightmare with this TV. First, this problem occurs
> intermittantly, the IK pulses do not reveal one specific tube as being bad.
> > >
> > > I've replaced and upgraded the BD board, all 3 CRT boards, and all 3
> CRTs. Yet the problem remains. The customer has stated that before the
> picture blanks and the light starts to blink 5 times, the OSD pops up. Also
> if he is changing channels the picture will blank intermittantly.
> > >
> > > Recently he is getting a green shifting of color before blanking. Also,
> the cutoff settings for the blue crt (new) are set at about 60 in comparison
> to the 30 setting for the RED/Green crts. I discovered on the last trip that
> his green anode connection was not mechanically connected to the HV
> Splitter, I reconnected that (that's when the green shift started
> occurring). This TV is too big to load in the van because it's too wide.
> > >
> > > I've checked the wiring, grounds, adjusted the screen controls, cutoff
> and drive settings in various configurations to increase the IK pulse output
> (it's not a flat-topped pulse, seems to have a slight curve to the leading
> edge).
> > >
> > > Have you seen any out-of-the-ordinary problems causing this? Has anybody
> recieved a defective CRT from Sony (that blue Crt bugs me). How about a bad
> splitter (internal resistance higher on one leg)? Anybody had a power supply
> that checks good but has caused IK failures ONLY to register?
> > >
> > > Damon Brunger
> > > damon101@xxxxxxxxxxxxxx
> > > Telrad Electronic Services
> > > Ft Wayne, IN 46815
> > >
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