Mighty Monarch of The Air

[vts1134]

I took an early day at work to spend some time on the set tonight. I also read through this entire thread a couple of times to come up with a game plan of tests for this evening. Here is what I'm thinking.#
I'm going to recheck the vertical height control selector.#
I'm going to check voltages on v13 and v14. I will connect my lead clips to the set and to my meter, then fire the set up for a measurement. After taking a measurement I'll remove power from the set and move on to the next voltage measurement.#
I'm going to disconnect both primary leads on my new t2 and connect them to the two leads on my variac. I'll fire the set up and turn up the variac to line voltage or robust deflection, which ever comes first.#
If deflection does not occur I will move on to OC's next suggestion of driving the coils directly with the variac. On this test I'm a bit hazy on. There is only one lead from the yoke on the vertical side. What would I do with the other lead on the variac?
After completing those test if I have time I'll move on to more.#

[VintagePC]

There is only one lead from the yoke on the vertical side. What would I do with the other lead on the variac?

The other side of the vertical is connected to ground according to the schematic (most likely chassis ground somewhere.)

you _SHOULD_ be able to connect the neutral side of the variac output (Be careful that you do really have neutral!) to the chassis, and then the HOT side to your coil wire.

HOWEVER, before you do that, double-check that your chassis is actually grounded or connected to line neutral. If your set has the possibility of a "Hot" or floating chassis voltage (i.e you do NOT read close to zero volts when measuring voltage from chassis to neutral in the wall plug), DO NOT DO THIS - it could trip your breaker!

Since you know the transformer is good though, if driving it with the variac produces no deflection, you can be almost certain the coils are the problem... and the test you're unsure about will produce little extra information.

[vts1134]

Taking off early to spend time on the set turned into run errands time I was able to do a voltage test on V13 and V14, however.
My results:
V13 according to the schematics should read- Pin 1: 170 to 40VDC. Pin 4: 6.3VAC. Pin 5:170-40VDC. Pin 6: -40 to -2.4VDC.
V13 actual readings- Pin 1: 51 to 20VDC. Pin 4: 7.5VAC. Pin5: 51 to 20VDC. Pin 6: -1.21 to -.97VDC.
V14 according to the schematics should read- Pin 3: 260 to 230VDC. Pin 4: 260 to 230VDC. Pin 6: 215VDC. Pin 7: 6.3VAC. Pin 8: 30 to 8VDC.
V14 actual readings- Pin 3: 350 to 300VDC. Pin 4: 445 to 230VDC. Pin 6: 295 VDC. Pin 7: 7.5VDC. Pin 8: 49 to 12VDC.

V14's readings are a bit high, but could those be within tolerance? V13's readings are low enough that I can't imagine they would be within tolerance. V13's readings on pins 3,4, and 8 change with the adjustment of V4a(the vertical size control). Schematics call for resistance of 2.5meg which is right what it metered to. I mentioned before that I wanted to change V13(a 6C4) but I haven't done that yet.

[Phil Nelson]

I would check resistors around and downstream of the oscillator, R65 and R66 especially, also R67 and R68 while you're in the neighborhood. You have partial deflection, suggesting that your oscillator is working somewhat, but its sawtooth is attenuated. You have already replaced obvious capacitors in that area. There ain't much left but resistors, so I would check those to eliminate 'em from the equation.

Also, C48 is the coupling cap for the oscillator. With a value of 4700 pf, I suppose it is a mica, but micas do croak sometimes.

Phil Nelson

[vts1134]

I tested R65-R69 previously and they all passed. I'll look into C48.

[old_coot88]

Any chance somebody could post the schematic of the entire vertical section? I re-read the thread to see if I'd missed it, but dint see it. oc

[Phil Nelson]

Here ya go.

http://antiqueradio.org/art/temp/Majestic1600.jpg

Grid and plate voltages of the oscillator tube are low. It would be interesting to sub that tube, or even look at things upstream.

Phil Nelson