Zenith color console 14B9C50

[Alex KL-1]

Is somewhat difficulty to see in the photos, but I have the impression that the fuse near the Hout tube are blown...

[pac.attack76]

I couldn't find my alligator clips so I just hooked a wire to both ends. I tried it twice and I'm not getting any changes.

[damen]

It's hard to see, but it doesn't look like your wire jumper is contacting the fuse leads, just the insulating spaghetti.

[JohnCT]

Originally Posted by pac.attack76

If I did it right on meter, it showed open. I'll jump it for a few secs. If jumping it, what will it do? Work normally or?

If everything is fine it will work normally.

Tubes are more forgiving than solid state - a SS horiz output will fail in 1/15K of a second, but you have more time to experiment with tubes. If you have insufficient drive to the output tube or if there's a load on the flyback, the tube will begin to "red plate".

In a dark room, jump the cathode fuse and watch the output tube as the TV warms up. If you see the plate begin to turn red, shut it down. If there's no red and the TV lights up with full raster and no nonlinearities or compression in the raster, it's probably good, but there might also exist an intermittent loss of horiz drive that will stress the output tube and open the cathode fuse, which is why you don't want to leave it jumped without constantly watching it.

John

[pac.attack76]

Originally Posted by JohnCT

If everything is fine it will work normally.

Tubes are more forgiving than solid state - a SS horiz output will fail in 1/15K of a second, but you have more time to experiment with tubes. If you have insufficient drive to the output tube or if there's a load on the flyback, the tube will begin to "red plate".

In a dark room, jump the cathode fuse and watch the output tube as the TV warms up. If you see the plate begin to turn red, shut it down. If there's no red and the TV lights up with full raster and no nonlinearities or compression in the raster, it's probably good, but there might also exist an intermittent loss of horiz drive that will stress the output tube and open the cathode fuse, which is why you don't want to leave it jumped without constantly watching it.

John

I'll get the clips today so I know it's jumped and I'll watch it.

[JohnCT]

Originally Posted by pac.attack76

I'll get the clips today so I know it's jumped and I'll watch it.

The other thing you can do instead of jumping out the fuse is to put your DMM set for reading milliamps (requires a lead change on the meter) in place of the fuse and watch the current. You should be getting a reading in the 200ma range somewhere give or take after 20 seconds or so.

If it stays low, the output tube is safe or the tube itself could be very weak, but if it goes over 250ma and keeps climbing past 300ma, shut it off.

John

[pac.attack76]

Originally Posted by JohnCT

The other thing you can do is to put your DMM set for reading milliamps (requires a lead change on the meter) in place of the fuse and watch the current. You should be getting a reading in the 200ma range somewhere give or take after 20 seconds or so.

If it stays low, the output tube is safe or the tube itself could be very weak, but if it goes over 250ma and keeps climbing past 300ma, shut it off.

John

Lead change?

[JohnCT]

Originally Posted by pac.attack76

Lead change?

Yes, you remove the red lead from the V, diode, ohm hole and move it to the ammeter side. Depending on your meter, it may have one or two holes for the ammeter side - one low (like below 400ma typically) and a higher one for several amps or more.

The black lead stays put.

John

EDIT: make sure to remove the lead from the ammeter hole when done as it presents essentially a dead short across the leads and you don't want to measure voltage in that manner.

[pac.attack76]

Originally Posted by JohnCT

Yes, you remove the red lead from the V, diode, ohm hole and move it to the ammeter side. Depending on your meter, it may have one or two holes for the ammeter side - one low (like below 400ma typically) and a higher one for several amps or more.

The black lead stays put.

John

EDIT: make sure to remove the lead from the ammeter hole when done as it presents essentially a dead short across the leads and you don't want to measure voltage in that manner.

Ah ok, move the red to top one. I've never used that one. First time for everything 😂

[pac.attack76]

Not sure of setting on meter but I moved red lead to other port and I'm getting readings up to .46 or .50. plate in tube starts to glow so I shut down.

[JohnCT]

Originally Posted by pac.attack76

Not sure of setting on meter but I moved red lead to other port and I'm getting readings up to .46 or .50. plate in tube starts to glow so I shut down.

That's a half amp of plate current - too much.

Horiz output tubes are pretty forgiving but don't run it under load until you figure out why it's red plating - it's either too little drive or too much load.

Leave the cathode fuse open and scope the horiz drive signal to the tube. Without the horiz cathode connected the waveform will be more of a square wave but the amplitude and frequency will be the same.

If there's no horiz drive, that's your problem. If you do have horiz drive, you have a load issue, and that can be a problem with the flyback, damper, yoke, etc.

John

[pac.attack76]

Originally Posted by JohnCT

That's a half amp of plate current - too much.

Horiz output tubes are pretty forgiving but don't run it under load until you figure out why it's red plating - it's either too little drive or too much load.

Leave the cathode fuse open and scope the horiz drive signal to the tube. Without the horiz cathode connected the waveform will be more of a square wave but the amplitude and frequency will be the same.

If there's no horiz drive, that's your problem. If you do have horiz drive, you have a load issue, and that can be a problem with the flyback, damper, yoke, etc.

John

I don't have the means to do that.

[pac.attack76]

Or at least I don't have a scope 😔

[JohnCT]

Originally Posted by pac.attack76

Or at least I don't have a scope 😔

Check the grid of the horizontal output with the cathode fuse out - you should get a negative DC voltage with respect to ground. On most Zenith horizontal outputs, that's pin 5. Look for at least -50VDC.

If that's missing, try a horiz osc tube and check all the voltages on the tube and the parts around it.

If your negative voltage is there, you have some kind of dynamic load on the flyback.

Most output red plating I can remember was due to insufficient drive.

John

[pac.attack76]

Originally Posted by JohnCT

Check the grid of the horizontal output with the cathode fuse out - you should get a negative DC voltage with respect to ground. On most Zenith horizontal outputs, that's pin 5. Look for at least -50VDC.

If that's missing, try a horiz osc tube and check all the voltages on the tube and the parts around it.

If your negative voltage is there, you have some kind of dynamic load on the flyback.

Most output red plating I can remember was due to insufficient drive.

John

So I need to remove that fuse? Pin 5 is G1 right?