Hi;

Here's a fun one. Side pincushion is way overcorrected. Top/bottom is
undercorrected. A few other things are off, but I think this is a major piece
of info. I remember corresponding in this NG awhile back about a problem where
all the data in the EPROM was reset to +127. The OP didn't give all details on
the symptom, but I think it was close.

On this set, the STK is working properly, and has been changed. Both red and
blue are affected the same way, although with the expected reversals of error.

( another post, on a Toshiba, is the blue convergence pushed harder than the
red ? On this one the blue is clipping uslightly/u more)

The STKs are only clipping because the drive is telling it to do probably three
times the output for which it was designed.

My major obstacle here is that it doesn't seem to see the convergence
subsystem, it gives me nothing. I got some options for setting default center
controls and a few other things, but nothing to do with convergence shows up.
In one mode (selected by the mute buttton) I can get the convergence to change
from severe over correction, to less severe overcorrection (with some T&B
correction starting to come in), and then a much less severe overcorrection
which doesn't even cause any on-screen clipping that I can see. The #6 key
toggles this. When I hit mute, or anything that exits this mode it reverts to
the severe side overcorrection and almost nothing on T&B. The way it is almost
seems like three picture modes on a widescreen model. The levels of ALL
corrections change, but not enough.

While the volume is supposed to change the data (on some), it does nothing, but
on a Zenith universal it does do the volume, even in service mode. The original
doesn't do anything. There is actually nothing shown on the screen to adjust
anyway, it seems not to know it's a projector.

On this model the green geometry is analog, with pots. Even though it goes
through the STKs, that part of it is working fine. The picture is also washed
out, but viewable, but the CRTs seem strong. Nice and sharp. I deem a software
problem of this nature has to be addressed first, agree ?

My thinking is that this is NOT in the output stage. You would need to increase
the values of both Vert conv yoke return resistors and decrease the value of
the Horiz conv yoke resistors. Defective STKs would have to have corresponding
gain errors. Three outcomes for each device and they all have to come in at
once, in that particular way ? I'd play a lotto ticket before checking those
resistors, and WTH do they have to do with the missing menu items ? Disagree ?
State your case, I'd like to hear the logic of how this could've happened.

Of course it could always be power supply, but not to the "PA00XX" chips. They
are obviously working. Problem is I got no print.

I need something on the architechture of this set.

Is there more than one EPROM ?

Are the option bits burned into the main micro ?

Does the reset routine include a secondary reset for the convergence subsystem
?

Does it handshake like an RCA ?

If it has a seperate convergence EPROM, where is it ?


All indications are that all the cells are set to 0, 255, + or -127 or
something like that, but it won't let me set anything. This seems consistent
with an initialization problem.

I know my posts are long, and I'm sorry, but how many times do we have to tell
people to be thorough ? Thanks for your time even reading this, and if you got
any answers or even ideas, they would be greatly appreciated. Thanks in
advance.

JURB

Jeff,
Look for a 2SD1276A regulator for the Horizontal Deflection to be leaky.

Good Luck on the rest.

Bill Jr

"JURB6006" wrote in message
...
Hi;

Here's a fun one. Side pincushion is way overcorrected. Top/bottom is
undercorrected. A few other things are off, but I think this is a major
piece
of info. I remember corresponding in this NG awhile back about a problem
where
all the data in the EPROM was reset to +127. The OP didn't give all
details on
the symptom, but I think it was close.

On this set, the STK is working properly, and has been changed. Both red
and
blue are affected the same way, although with the expected reversals of
error.

( another post, on a Toshiba, is the blue convergence pushed harder
than the
red ? On this one the blue is clipping uslightly/u more)

The STKs are only clipping because the drive is telling it to do probably
three
times the output for which it was designed.

My major obstacle here is that it doesn't seem to see the convergence
subsystem, it gives me nothing. I got some options for setting default
center
controls and a few other things, but nothing to do with convergence shows
up.
In one mode (selected by the mute buttton) I can get the convergence to
change
from severe over correction, to less severe overcorrection (with some T&B
correction starting to come in), and then a much less severe
overcorrection
which doesn't even cause any on-screen clipping that I can see. The #6 key
toggles this. When I hit mute, or anything that exits this mode it reverts
to
the severe side overcorrection and almost nothing on T&B. The way it is
almost
seems like three picture modes on a widescreen model. The levels of ALL
corrections change, but not enough.

While the volume is supposed to change the data (on some), it does
nothing, but
on a Zenith universal it does do the volume, even in service mode. The
original
doesn't do anything. There is actually nothing shown on the screen to
adjust
anyway, it seems not to know it's a projector.

On this model the green geometry is analog, with pots. Even though it goes
through the STKs, that part of it is working fine. The picture is also
washed
out, but viewable, but the CRTs seem strong. Nice and sharp. I deem a
software
problem of this nature has to be addressed first, agree ?

My thinking is that this is NOT in the output stage. You would need to
increase
the values of both Vert conv yoke return resistors and decrease the value
of
the Horiz conv yoke resistors. Defective STKs would have to have
corresponding
gain errors. Three outcomes for each device and they all have to come in
at
once, in that particular way ? I'd play a lotto ticket before checking
those
resistors, and WTH do they have to do with the missing menu items ?
Disagree ?
State your case, I'd like to hear the logic of how this could've happened.

Of course it could always be power supply, but not to the "PA00XX" chips.
They
are obviously working. Problem is I got no print.

I need something on the architechture of this set.

Is there more than one EPROM ?

Are the option bits burned into the main micro ?

Does the reset routine include a secondary reset for the convergence
subsystem
?

Does it handshake like an RCA ?

If it has a seperate convergence EPROM, where is it ?


All indications are that all the cells are set to 0, 255, + or -127 or
something like that, but it won't let me set anything. This seems
consistent
with an initialization problem.

I know my posts are long, and I'm sorry, but how many times do we have to
tell
people to be thorough ? Thanks for your time even reading this, and if you
got
any answers or even ideas, they would be greatly appreciated. Thanks in
advance.

JURB