Sony 9-306UB Vertical Scan Fault

[Doctor Hue]

I have a Sony 9-306UB that has a vertical scan fault. The Horizontal and vertical are locked and don't roll but the vertical picture is only displayed on the top 2/3 of the CRT, the image flickers and there seem to be two images, one above the other squashed vertically. See attached picture. The picture shows
the Sony 9-306UB on the left and a Sony 9-90UB on the right both being fed with a UHF 625 line signal.

Pushing both UHF and VHF buttons in on the 306UB does not seem to give the UHF/405 option that I get with the 9-90UB - is this correct ?

Has anyone seen this vertical fault on the 306UB ?

I'm also nervous of taking the unit apart as I've read the case can be broken very easily. Any help/advice would be most appreciated.

[Mr Hoover]

Hello...You'll have to take the back off I'm afraid...However it's not that difficult and whilst the case is more fragile than the later 990UB model as long as it's not dropped etc no damage should occur.

You will need to change the electrolytic capacitors in the frame timebase section which have probably dried up,causing your problem....These are quite easily got at and are on the lower left side of the bottom vertical panel,below the CRT assembly.

You might find this thread from some years ago useful
https://www.vintage-radio.net/forum/...ad.php?t=27751

The panel/board I'm referring to is the 4th picture from the left in the 3rd post from the bottom of the thread.

Before doing this you could try tweaking the vertical linearity preset which is on the bottom of the board,there's also a vertical bias preset next to it.

These presets can be prone to poor/intermittent contact and might be the source of your problem.From memory you won't get the Uhf/405 option with both buttons pushed in.

Cheers

Hugh

[Studio263]

They all get like this, the capacitors seem to go ***up*** in value which makes the frame timebase run too slow and messes up the linearity. Here's my complete write-up on the subject:

https://www.vintage-radio.net/forum/...ad.php?t=93616

These sets are difficult to work on as you can't reach the reverse side of the panels easily, the TV9-90UB is much easier in this respect. That being said, it can be done - it just takes time and a bit of care.

The standards switching arrangement is different to that of the TV-9-90UB as there is a relay involved as well as the push switches, I don't think that combinations of the buttons other than the standard "one or the other pushed in" give workable results with this model.

[Mr Hoover]

Originally Posted by Studio263

the capacitors seem to go ***up*** in value l.

Bear in mind with all Sony TV electrolytic capacitors of this era (which I was told about some years ago by a guy in the States who restored old Sonys)that the value on the can is the "minimum" capacitance and it could easily be 20-50% more in practice..Not like nowadays of course.

Hugh

[Studio263]

Read the write-up, more than +100% in some cases! The circuit cannot function with these values so the change must have occured after manufacture and a long period of satisfactory operation (about 20 years for this set it would seem). The TV9-90 was much better in this respect, the whole thing seems to last almost indefinitely.

[Mr Hoover]

Originally Posted by Studio263

Read the write-up, more than +100% in some cases! .

I read it...Have restored 4 9-306UB's and the Continental cousin 9-306UM..

When working on these (and earlier Non UK market Sonys) I change all electrolytics immediately.

[Doctor Hue]

Thanks guys for your info.

Mr Hoover, I see that you have a service manual !

Any chance you could upload the circuit diagram of the vertical scanning section ?

[Mr Hoover]

Hope this helps....

The manual goes into great detail on IF realignment and Sony part no's for spares but is vague in a lot of other areas.

Hugh

[Doctor Hue]

Originally Posted by Mr Hoover

Hope this helps

Thanks very much Mr Hoover.

Now to get cracking...