Sony 5-303E off-center image problem

[TechneMoira]

Hello Videokarma friends!

I'm currently restoring a Sony 5-303E portable TV. I have a very annoying problem however.

I managed to make the picture reasonably symmetrical in vertical and horizontal directions, and stable vertical deflection. However, I cannot center the image dead center on the CRT. That is, I COULD center it, but when I do the image goes all haywire and a weird screeching noise comes out of the TV (speaker ?).
Only when the image is off-center (on the right looking at the CRT front) does it remain stable. When i try to adjust the horizontal position from the right to the left to center it, first the top of the image starts to go all jagged and wavy. Then, when i try to push the image even further to the center, it goes completely bananas.

B+ is normal, current-draw is normal, no overheating parts, no sparks, picture is stable (off-center), all electrolytics have been replaced, brightness and contrast can be set normally over the whole range (0 to 100%). Possibly/probably badly aligned sound IF (good picture - no sound / no picture - good sound).

Would the problem have anything to do with the horizontal deflection oscillator? Or should i look for the cause elsewhere?


At this stage I'm a bit mystified what could cause this problem. Any idea where to look for the problem or how to diagnose it (without a scope.. .mine broke down unfortunately ) ?

Thanks
Cordially

[Eric H]

I don't know about the little Sony's but most B&W sets of that era had magnetic rings on the back of the yoke for centering the picture.

You can shift the picture somewhat with the horizontal hold but eventually it will get too far off frequency and fall out of sync.

[zeno]

Dont have a manual but........
They may be shifting the hoz phase to center it.
The noise is prob. the hoz osc screaming. Be sure
all the 'lytics are changed & in right in the hoz.
Check the phase diodes also. Try the rings as Eric said.
Do the adjustments by the book if there are special instructions.
Keep in mind ALL sets overscan & the centering may not
be perfect but it should fill the screen. Last thing is you
gotta watch what you are feeding it. The set was made to
do off air NTSC & often older sets have troubles with
anything not giving a perfect NTSC signal.

73 Zeno