J
JURB6006
Guest
Hi;
Here's a few wierdo things:
NAP PTV375 and similar:
Intemittent shutdown and you have literally checked just about everything ?
That one single wire connecting the ABL from the PS board to the "main"
chassis. If the picture is turned high enough and the set has strong guns in
the tubes, the jungle IC doesn't get the ABL voltage and the set will go into
OCSD. The break in the wire was not visible and on top of that it was
intemittent ! Also note that on some of these the phosphor is actually wearing
out, so don't assume that if the picture isn't all that bright, that the gun is
not putting out strong beam current. This wire is also a handy test point to
see if that is the case.
Comment: Is it possible that when the focus is going on these it is not the
gun, but the phosphor ? I've tried 2+4+6 pole beam shaping magnets to no avail.
Sony XBR series RPTV with subwoofer:
Some have the wires to the subwoofer going through a hole in the chassis assy.,
these must be connected to a load or the set will shutdown. I see no reason for
the set to be designed like this unless the subwoofer uses current drive (like
convergence) and equalizes with those parameters. The only other reason would
be to trip us up, or possibly to make sure nobody ever hears one with a blown
out sub. . . . .
Sony direct view XBR series with AKB:
After CRT replacement grey scale is incorrect, cure is to adjust the vertical
hieght. Yes. Generally color(s) go away, yet the AKB is active and there is
video. In depth troubleshooting revealed this, with the trace just right on my
scope, it showed more feedback from the missing color(s). IIRC the sequence is
RGB, so have a look at the actual AKB pulses when you have a drastic error in
greyscale when the video stays active. My reasoning is that the only thing that
could cause this is that the envelope for the rebuilt tube was not designed for
a set with AKB. These tubes must have a coating or something to keep the AKB
from picking up feedback from the aperature grill frame. Any other theories are
welcome. If indeed there is such shielding in these tubes, facts in evidence
indicate that incorrect V hieght could cause AKB shutdown. I guess in these
when they say set it to a certain overscan, they mean it. Even if you have
really good convergence, the slightest error is greater off screen, and in my
case the missing colors were a bit high at the top by less than a raster line.
Who knows what it was off screen.
"Heads up !" posts might be a good idea, and I would like to encourage the
really good techs in here (you know who you are) to do this from time to time.
After you get home, still fresh on your mind, when you get a little time. Now I
didn't put "Heads up!" this or that because this post has three different
topics. If you only have one it wouldn't be a bad idea to put chassis or model
in there. I'll probably save most of them. I'll just have a headsup directory
on the harddrive I guess.
Whadya all think ?
JURB
Here's a few wierdo things:
NAP PTV375 and similar:
Intemittent shutdown and you have literally checked just about everything ?
That one single wire connecting the ABL from the PS board to the "main"
chassis. If the picture is turned high enough and the set has strong guns in
the tubes, the jungle IC doesn't get the ABL voltage and the set will go into
OCSD. The break in the wire was not visible and on top of that it was
intemittent ! Also note that on some of these the phosphor is actually wearing
out, so don't assume that if the picture isn't all that bright, that the gun is
not putting out strong beam current. This wire is also a handy test point to
see if that is the case.
Comment: Is it possible that when the focus is going on these it is not the
gun, but the phosphor ? I've tried 2+4+6 pole beam shaping magnets to no avail.
Sony XBR series RPTV with subwoofer:
Some have the wires to the subwoofer going through a hole in the chassis assy.,
these must be connected to a load or the set will shutdown. I see no reason for
the set to be designed like this unless the subwoofer uses current drive (like
convergence) and equalizes with those parameters. The only other reason would
be to trip us up, or possibly to make sure nobody ever hears one with a blown
out sub. . . . .
Sony direct view XBR series with AKB:
After CRT replacement grey scale is incorrect, cure is to adjust the vertical
hieght. Yes. Generally color(s) go away, yet the AKB is active and there is
video. In depth troubleshooting revealed this, with the trace just right on my
scope, it showed more feedback from the missing color(s). IIRC the sequence is
RGB, so have a look at the actual AKB pulses when you have a drastic error in
greyscale when the video stays active. My reasoning is that the only thing that
could cause this is that the envelope for the rebuilt tube was not designed for
a set with AKB. These tubes must have a coating or something to keep the AKB
from picking up feedback from the aperature grill frame. Any other theories are
welcome. If indeed there is such shielding in these tubes, facts in evidence
indicate that incorrect V hieght could cause AKB shutdown. I guess in these
when they say set it to a certain overscan, they mean it. Even if you have
really good convergence, the slightest error is greater off screen, and in my
case the missing colors were a bit high at the top by less than a raster line.
Who knows what it was off screen.
"Heads up !" posts might be a good idea, and I would like to encourage the
really good techs in here (you know who you are) to do this from time to time.
After you get home, still fresh on your mind, when you get a little time. Now I
didn't put "Heads up!" this or that because this post has three different
topics. If you only have one it wouldn't be a bad idea to put chassis or model
in there. I'll probably save most of them. I'll just have a headsup directory
on the harddrive I guess.
Whadya all think ?
JURB