Sylvania 336mu

[Username1]

Originally Posted by Electronic M

Don't worry too much about voltages within 20% of correct (such as the pin 6 reading) those should be within tolerance.

Which stage is the 12AU7 in? A horizontal line on the screen is a symptom of Vertical deflection failure...So you should be scrutinizing the voltages and components in and around the the Vertical multivibrator/oscillator, output tubes.

Here is a quick test that can clear the vertical deflection transformer and yoke (the most rare/costly parts). If you have a variac disconnect the primary of the vertical output transformer, and connect it to the variac. With the set on slowly crank up the output voltage of the variac, and if that line expands vertically before you hit max output, then your yoke and output transformer are functional....If the line don't expand disconnect the vertical winding of the yoke connect it to the variac, and repeat.

Really....? On the surface I think it would work.... But I can't see going above
20V..... Anywhere near max output with only the unit's fuse could put
2 - 3 or more amps into it.... Cooking it for sure I would think....

Have you actually done this....?

At the 20V I would be looking for just a small deflection, not full screen.....

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sylvania

Join Date: Feb 2015
Posts: 12
sylvania deflection loss
I am giving you a update and hope i am replying correctly, This set is Sylvania 336m. I am supplying chassis with 117v line load is 2.56 amps.I have sound and a horizontal line across CRT, I checked the voltage on tube 12AU7 which if I read the print correctly is the oscillator section. Pin number 1 on the photofact shows 235v, on that pin I am reading 333v.Photofact shows pin number 6 at 135v, my reading on pin 6 is 113v. This is with line voltage at 117v which the photofact refers to when checking voltages. This chassis has been recapped and new electrolytics, I checked the electrolytics again and they show good. After I had recapped this set I had deflection and then is slowly went to horizontal line only. Thank you

A higher voltage on the plate usually means the tube is turned off.... not working....

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[Electronic M]

Originally Posted by Username1

Really....? On the surface I think it would work.... But I can't see going above
20V..... Anywhere near max output with only the unit's fuse could put
2 - 3 or more amps into it.... Cooking it for sure I would think....

Have you actually done this....?

At the 20V I would be looking for just a small deflection, not full screen.....

Not direct to the yoke, but the primary of the transformer should be able to take it since the output tube should create a few hundred volts AC across it. The goal is not to hit max variac output, but rather to get 1-2 thirds deflection to confirm the transformer and yoke work....Once decent deflection is obtained more voltage serves no purpose.

[sylvania]

The 12AU7 I am referring to is the horz oc and horz discharge section, I had thought the voltage being 100v higher on that pin was causing a problem elsewhere in the set, I will check the vertical section next. I know the Vertical output tube pins read correct voltage.