I have an older crt projection big screen and I now have retrace lines
that appeared after turnning the set on a few times and hearing a arc
immediatly when turnning on. I waited too long to fix the arc and it
has affected something else.

The arcing was comming from the Red CRT from under the node and arcing
to the chassis, I have since fixed this but have been unable to track
down what is causing the retrace lines. The B+ voltage appears correct
but I do not have an oscilloscope to test ripple in any of the parts.
Any one know what the arcing may have effected ? The blanking circut or
perhaps from the flyback backwards ?

Post the rest of the troubleshooting information so someone can point
you in the right direction. Things like which crts have the retrace
lines, crt voltage measurements, etc..

The retrace lines are all white, so it should be comming from all of
the crt's. The model is Hitachi CT4532, I have a pdf service manual for
it. And can make this available to anyone interested.
www.bauld.com/~eric/ct4532.zip

B+ was at 111 V Should be 110
Unsure of the crt voltage, or how to test that yet.

I am trying to get my hands on a ocsilloscope for further tests.

Im rather new to electronics repair, so I learn as much as I can as I
go. I have wanted to do electronics repair for some time as a hobby. I
have been reading, reading and more reading but know far from
everything

You don't need an o'scope yet. Simply measure all the voltages
(carefully) that are on the crt circuit boards. Pay special attention
to the approximately +200Vdc going to the video output and the
G2/screen voltage. If there is a G1 voltage that could be important
also.

Those are the three "common" voltages for all three crts.

I tested the voltages on the three CRT boards.... and provided I did it
correctly. (I followed the servic manual schematics)
I only read approx 70V - 82V(once warmed up) dc on each one of the CRT
circuit boards, Service manual says it should be 200V

The screen voltage read around 776 give or take a few volts, there was
nothing on G2 Voltage found in the service manual, I am guessing that
screen is G2 voltage. And I could not find out what it should be in the
schematic, it just listed it as screen.

Looks like the the +200V is way off....
Have to figure out where to go from here now.

Charon wrote:
I tested the voltages on the three CRT boards.... and provided I did it
correctly. (I followed the servic manual schematics)
I only read approx 70V - 82V(once warmed up) dc on each one of the CRT
circuit boards, Service manual says it should be 200V

The screen voltage read around 776 give or take a few volts, there was
nothing on G2 Voltage found in the service manual, I am guessing that
screen is G2 voltage. And I could not find out what it should be in the
schematic, it just listed it as screen.

Looks like the the +200V is way off....
Have to figure out where to go from here now.



Yeah Screen = G2, IIRC it's a few thousand volts on most sets.


Trace the 200V back to wherever it comes from, might be as simple as a
resistor that's gone high.

Where was the ground lead of your meter during your testing?

If you had the ground lead of the meter on the ground that was going to
the crt pcbs then yes the +200v is way too low.

The G2/screen voltage typically reads on a meter between 350 and 900
volts on most sets depending on where it is adjusted and the specific
crts in use.

At this point you could have an open 200v line fusible resistor, and/or
a damaged video output device that is loading down the 200v line.

Charon wrote:
The retrace lines are all white, so it should be comming from all of
the crt's. The model is Hitachi CT4532, I have a pdf service manual for
it. And can make this available to anyone interested.
www.bauld.com/~eric/ct4532.zip

B+ was at 111 V Should be 110
Unsure of the crt voltage, or how to test that yet.

I am trying to get my hands on a ocsilloscope for further tests.

Im rather new to electronics repair, so I learn as much as I can as I
go. I have wanted to do electronics repair for some time as a hobby. I
have been reading, reading and more reading but know far from
everything



Well it sounds like you're off to a decent start, be real careful using
a scope on a TV, it's absolutely imperative that you use an isolation
transformer to power the TV for that. Good luck, projection sets can be
a real pain.

Charon wrote:
I have an older crt projection big screen and I now have retrace lines
that appeared after turnning the set on a few times and hearing a arc
immediatly when turnning on. I waited too long to fix the arc and it
has affected something else.

The arcing was comming from the Red CRT from under the node and arcing
to the chassis, I have since fixed this but have been unable to track
down what is causing the retrace lines. The B+ voltage appears correct
but I do not have an oscilloscope to test ripple in any of the parts.
Any one know what the arcing may have effected ? The blanking circut or
perhaps from the flyback backwards ?



Are the retrace lines on all three CRTs?

Post the brand, model, and chassis. Post the info that others have asked
for, too. More info yields better advice. Less info yields guesses, except
from the true psychics on this group. Actually, I guess a true psychic
would not need to read the group at all. Maybe phychos is more likely on
usenet...

Most likely thing would be an open resistor, but with HV arcing things can
get unpredictable.

Could be unrelated to the arcing, if the arcing was caused by a coolant leak
like we see on some of the RCA sets. Could also be that the CRT was
damaged.

Leonard

"Charon" wrote in message
oups.com...
I have an older crt projection big screen and I now have retrace lines
that appeared after turnning the set on a few times and hearing a arc
immediatly when turnning on. I waited too long to fix the arc and it
has affected something else.

The arcing was comming from the Red CRT from under the node and arcing
to the chassis, I have since fixed this but have been unable to track
down what is causing the retrace lines. The B+ voltage appears correct
but I do not have an oscilloscope to test ripple in any of the parts.
Any one know what the arcing may have effected ? The blanking circut or
perhaps from the flyback backwards ?

Charon wrote:
I have an older crt projection big screen and I now have retrace lines
that appeared after turnning the set on a few times and hearing a arc
immediatly when turnning on. I waited too long to fix the arc and it
has affected something else.

The arcing was comming from the Red CRT from under the node and arcing
to the chassis, I have since fixed this but have been unable to track
down what is causing the retrace lines. The B+ voltage appears correct
but I do not have an oscilloscope to test ripple in any of the parts.
Any one know what the arcing may have effected ? The blanking circut or
perhaps from the flyback backwards ?

It's usually a driver or output filter circuit resistor/capacitor open
or change in value,
guess you will have to test by substitution. Could also be crt did you
try swapping the
crt drive boards? If the lines go away its in the drive circuit if
they stay then it probably the
red crt.