View Full Version : Sony 5-303W Blank Screen


Arcanine
02-04-2015, 11:50 PM
I've pretty much entirely recapped the board and this is all it still gives me.

http://img.photobucket.com/albums/v480/RileyWestwolf/IMG_0790_zpsdlpvv25q.jpg (http://smg.photobucket.com/user/RileyWestwolf/media/IMG_0790_zpsdlpvv25q.jpg.html)

it has a few less lines, but I don't get it. What is this particular issue? Bad transistor?

Eric H
02-05-2015, 01:46 AM
It looks like the Horizontal Frequency is way off. Does it have sound, can you see any movement at all on the screen?

Findm-Keepm
02-05-2015, 09:50 AM
Wires on mine are very brittle - perhaps you broke a wire or two? Check the voltages around the horizontal oscillator and you'll likely find a problem. Crisp looking picture, just need to pull the oscillator in to sync.

Cheers,

Arcanine
02-05-2015, 10:28 AM
It looks like the Horizontal Frequency is way off. Does it have sound, can you see any movement at all on the screen?

Yes. It has sound and reception. I can faintly see static on empty channels. When I tune to my transmitter I get perfect sound but no movement otherwise.

Perhaps the 2SC41 transistor is bad? It does get fairly warm.

zeno
02-05-2015, 02:24 PM
Going with hoz freq off is there a sub hold on the PCB ?
If so may have bad spot.
If the 2SC41 is the hoz out it may be cause the freq is off.
Transistors almost always work or not so I dont think
thats it. In any case dont run it long if its hot or it
will short.

73 Zeno:smoke:

Eric H
02-05-2015, 04:14 PM
I noticed on my set it has some adjustments (four pots) right above the speaker, probably Vert height and lin but maybe one of them is the Sub Horiz adjustment?

Arcanine
02-05-2015, 05:19 PM
I noticed on my set it has some adjustments (four pots) right above the speaker, probably Vert height and lin but maybe one of them is the Sub Horiz adjustment?

I'm not sure. I replaced a blown vert. driver transistor today on one of my sets and it brought vertical totally back. I'm going to tackle this set now. I was angry when it died.

Lucky for me chesters has all these transistors in stock.

jr_tech
02-05-2015, 05:51 PM
I noticed on my set it has some adjustments (four pots) right above the speaker, probably Vert height and lin but maybe one of them is the Sub Horiz adjustment?

Yep! fourth hole from the rear. From rear; Focus, Vert Height, Vert Linearity, Horizontal Frequency and Vertical Output Bias (covered).

jr

Arcanine
02-05-2015, 06:09 PM
Yep! fourth hole from the rear. From rear; Focus, Vert Height, Vert Linearity, Horizontal Frequency and Vertical Output Bias (covered).

jr

I finished recapping the board and it still has the same symptom. I also changed the Horz. Driver transistor, same thing. either the actual output is bad, but that I doubt as it's still getting warm.

I'm thinking the bias transistor it self is bad.

jr_tech
02-05-2015, 06:35 PM
Does tweeking the Horizontal Frequency pot have *any* effect at all on the number or angle of those bright horizontal lines? have you tried cleaning the pot?

jr

Arcanine
02-05-2015, 07:29 PM
Does tweeking the Horizontal Frequency pot have *any* effect at all on the number or angle of those bright horizontal lines? have you tried cleaning the pot?

jr

It shifts them around a little, but it has almost no effect on them at all.

jr_tech
02-05-2015, 08:05 PM
It shifts them around a little, but it has almost no effect on them at all.

Hmmmm..... I'm stumped, mine seems to have a profound effect on horizontal frequency, to the the extent of almost killing the horizontal oscillation (squigging) when turned fully clockwise.

jr

Arcanine
02-05-2015, 11:57 PM
Hmmmm..... I'm stumped, mine seems to have a profound effect on horizontal frequency, to the the extent of almost killing the horizontal oscillation (squigging) when turned fully clockwise.

jr

Adjusting the horz. frequency alters the screen size a little and makes the lines move around, not much else.

Turning the horz. on the front of the set moves the lines around a little.

I'm at a bit of a loss.

EdKozk2
02-06-2015, 02:19 AM
Did you try adjusting L15, the horizontal stabilizer transformer coil? It looks like a square transistor radio IF coil. It's mounted on the Sweep circuit board, center left
viewed from the component side.
Ed

etype2
02-06-2015, 09:08 AM
I see you have it tuned to channel 13. Have you tried the set with a digital converter on channel 3 or 4?

kvflyer
02-06-2015, 10:52 AM
If I read correctly in the first post, the set was recapped? Could one of the capacitors in the horizontal oscillator be off by a factor of 10? For instance, if it called for a .001 FD maybe a .01 FD was installed?

Just a thought.

Arcanine
02-06-2015, 11:41 AM
I see you have it tuned to channel 13. Have you tried the set with a digital converter on channel 3 or 4?

I have a Blonder Tongue modulator. Channel 13 is the channel I have best clarity with in my house.

And all the capacitors where carefully selected and replaced to have nearly identical values. The only one I had issues with was the 2uF caps. I replaced those with NP 2.2uF caps.

This set had the identical symptom before I even changed out the caps. It basically changed nothing.

Arcanine
02-06-2015, 12:48 PM
I opened up my working set, and removed the sweep board for compareson. After studying both boards I found a .01 cap is missing on the top section of the board.

It's a cap I don't have so I have to make a run out to Chesters.

The missing cap is in the horizontal section.

etype2
02-07-2015, 04:26 PM
I have a Blonder Tongue modulator. Channel 13 is the channel I have best clarity with in my house.


Was just wondering if the modulator had something to do with scrambled image.