It's ripple in the PSU. The Trinitrons have a central caged PSU under the tube neck, slide that out and replace the smaller electros in it but not the very large one.

It's also worth cheking the marked points for the PSU voltages with your multimeter set to AC volts, as this will show ripple.

thanks for the advice!! did you mean a part of the main power supply or a separate power unit which was attached to the NECK card ? could you please locate it the service manual i have attached here?

 

hey check post #16

 

hey check post #16

thanks for writing me ! i was unable to touch the unit yet. i am doing it Saturday evening ! will update you. otherthan that, is there anything to to ?

 

Thanks for the advice! I found 12V, B+ voltage goes to the tuner. hope this is the voltage you have mentioned here. can a bad "varicap diode" cause this issue ? could you please see the service manual i have attached herewith.

Varicap diodes rarely go bad. Near the tuner there is often a resistor and zener diode. Although some tuners may generate the bias voltage internally, or newer designs might not require it at all. I've seen the odd LCD with it.

 

thanks for the advice!! did you mean a part of the main power supply or a separate power unit which was attached to the NECK card ? could you please locate it the service manual i have attached here?

The main power supply is in a large shielded metal box right in the middle of the TV, at the bottom (under the neck board). It slides out. Replacing the smaller electros in the PSU is one of the first things to do when Trinitron gets to the workbench.

 

Thanks!!!

Thank for all help and expert comments you guys gave me on correcting this issue. i was able to fix it!! it was a DRY-JOINTS issue inside the IF unit. it was Ok after re-soldering all the IF units components. now it looks nice........

i have another a little thing to ask ..but this seems to be a somewhat silly question.... but i have noticed it...

My home is by a main road .... after i fixing this issue; this TV is more sensitively respond for interference which makes by vehicles. in short, when a vehicle goes, it it displays some cross liens across the screen. (just like when lightning happening ). can this be another problem ? any idea?

 

hey check post #16

Thanks!!!

Thank for all help and expert comments you gave me on correcting this issue. i was able to fix it!! it was a DRY-JOINTS issue inside the IF unit. it was Ok after re-soldering all the IF units components. now it looks nice........

i have another a little thing to ask ..but this seems to be a somewhat silly question.... but i have noticed it...

My home is by a main road .... after i fixing this issue; this TV is more sensitively respond for interference which makes by vehicles. in short, when a vehicle goes, it it displays some cross liens across the screen. (just like when lightning happening ). can this be another problem ? any idea?

http://forum.allaboutcircuits.com/editpost.php?do=editpost&p=407507

 

The main power supply is in a large shielded metal box right in the middle of the TV, at the bottom (under the neck board). It slides out. Replacing the smaller electros in the PSU is one of the first things to do when Trinitron gets to the workbench.

Thank for all help and expert comments you gave me on correcting this issue. i was able to fix it!! it was a DRY-JOINTS issue inside the IF unit. it was Ok after re-soldering all the IF units components.

However im still unable to locate the caps you have told me... in this system, the main power supply hadn't come as a shielded metal box. it was on one edge of the main board. can you please show me where you say in the pic, i have attached herewith.

there is a shielded metal box in the middle but it's not a power supply ..... what do u mean by the PUS (Power Supply Unit ?) are the PSU and the main power supply means a same unit? PLS DONT MISUNDERSTAND ME, IM NOT WORKING IN ELECTRONIC REARING FIELD.. I HAVE NO EXPERIENCES ON TROUBLESHOOTING AS YOU GUYS DO.... SO SOME THINGS CANT BE UNDERSTAND QUICKLY

 

Ha! Nailed it on the first shot...not bad huh!

You don't need to change anything if the picture is OK...
Leave it.
Come back if you have any other issue.

The interference could be the result of ur soldering. U said u took out the tuner, to reflow, so you need to check it. U need to resolder all the ground terminals properly.
Don't leave any ground joints de-soldered.

Did you meddle with any adjustments?

 

Did you actually check the PSU ripple? There is definite evidence of mains freq "banding" showing in your last 2 photos.

How many years has it been since the caps were done? That's an old TV set.

 

Did you actually check the PSU ripple? There is definite evidence of mains freq "banding" showing in your last 2 photos.

How many years has it been since the caps were done? That's an old TV set.

please tell me what do you mention by "PSU" ? is it the main power supply (switching mode unit) or another special unit ?

 

Ha! Nailed it on the first shot...not bad huh!

You don't need to change anything if the picture is OK...
Leave it.
Come back if you have any other issue.

The interference could be the result of ur soldering. U said u took out the tuner, to reflow, so you need to check it. U need to resolder all the ground terminals properly.
Don't leave any ground joints de-soldered.

Did you meddle with any adjustments?

Dear friend, thanks you very much for the time you spend to reply me. i'll re sold it as you said. just tell me for my knowledge, is it not enough to sold only one leg of the tuner unit?, coz all are in one ground-path.

Another thing, one friend ( "THE_RB"), asked me to heck the PSU ripple? could you please tell me what is this PUS unit ? is it the main power supply (switching mode unit) or another special unit ?

i'm not working in the electronic field, so i need to improve my knowledge

 

If a shielding needs just one ground why do you think people who made these use more than just one ground points. There is a reason why multiple points are used in RF circuits. The interference could be a grounding issue.

And you never answered that if you had turned any of the adjustments.

The other member's are talking about power supply unit. Since you have clear pictures, your TV does not have any issue as said.
U need to show me a picture of any other problem if you have any.

Next you need to clean the black residue build up around the Fly back and the around the tube. This will help in minimizing ignition noise picked up by the set.

U need to clean ur TV properly before you cover it up.

Plus u need to make sure there are no other dry joints around the RF circuitry and any other area that dissipates lots of heat or any area which has heat sinks and power resistors

 

If a shielding needs just one ground why do you think people who made these use more than just one ground points. There is a reason why multiple points are used in RF circuits. The interference could be a grounding issue.

And you never answered that if you had turned any of the adjustments.

The other member's are talking about power supply unit. Since you have clear pictures, your TV does not have any issue as said.
U need to show me a picture of any other problem if you have any.

Next you need to clean the black residue build up around the Fly back and the around the tube. This will help in minimizing ignition noise picked up by the set.

U need to clean ur TV properly before you cover it up.

Plus u need to make sure there are no other dry joints around the RF circuitry and any other area that dissipates lots of heat or any area which has heat sinks and power resistors

no i didn't do any adjustments...

 

This came in my PM.

dear friend;

Thanks for helping me for fixing My TV issue. i did sold all the grounding points as you said. all issues seems to be OK!

can you tell me one thing? i saw screen color got reduce a little (and a contrast change) can you suggest some thing to do ?

regards!
Kushan

No need for PM Mate.
Post ur problem here.

Purpose for me being here is to teach others of what I know.

As for ur problem.
Display a clean picture. Preferably from ur dvd player.
Next set the brightness and picture setting from the menu to maximum.

Take a picture, see that ur picture is as clear as possible. For me understand this problem I need to see a good picture shown by the TV.
Post ur picture.