Need some help on an 8TS30....

[Kevin Kuehn]

Originally Posted by Kamakiri

What range should it read?

Based on Riders voltages I'm coming up with 39.4v across R127B, which would be about 6.77 watts. Or 57.4v from the left side terminal to ground. 9.84 watts dissipated between those three series resistors. Then another 9.323 watts across R127A and R128A. For a grand total of 19.16 watts in the chimney. Does that sound feasible?

[old_coot88]

So based on 40V max across R127B, it should be rated at at least 10W, preferably higher (I'd prefer much higher for cooler running).

[Kevin Kuehn]

Originally Posted by old_coot88

So based on 40V max across R127B, it should be rated at at least 10W, preferably higher (I'd prefer much higher for cooler running).

Sams lists it as a 10 watt. 17 watt for R127A. They're really banking on that chimney to draw cool air in.

[Kamakiri]

Okay, something's still very wrong. Here's where I'm at.....

I found a 7K ohm 10 watt in my stock. Close enough to give it a try. I'm getting 39.8 V across R127B, so we're right there in the correct range. Now, the horizontal linearity is WAY off, compressed on the left side (as I recall).

But everything's getting hot still. Really hot...to the point where something was starting to give a wisp of smoke. When I lifted the leads off R127B after the set was shut down for a couple minutes they were still extremely warm. The contrast/AGC control does almost nothing now, and the picture has slightly less width than it had.

Here's my work as it is now. The 12 ohm resistor to chassis ground checks out fine.

[old_coot88]

OK, now try the same power-up except with the 6BG6, damper, vert.output, and audio output tube removed, while monitoring voltage across R127B. It should drop 'waay down with those heavy-draw tubes removed.
If it doesn't, try the ohmmeter test suggested in post# 75.

[Kamakiri]

I'll pick it up here tomorrow. Gotta go work the night shift on the railroad tonight

[Electronic M]

Originally Posted by Kamakiri

I'll pick it up here tomorrow. Gotta go work the night shift on the railroad tonight

Good ol' Lionel "O" scale model RR...Used to set up my father or grandfather's set 'round the tree most Christmases....The tracks liked to push apart when the train went over it and speed dropped a lot on the far side from the power connection to the tracks.....Until I tried tying the track sections together, then they did not come apart and power loss along the tracks dropped significantly.

[Kamakiri]

Originally Posted by Kevin Kuehn

Based on Riders voltages I'm coming up with 39.4v across R127B, which would be about 6.77 watts.

I'm at 45.8v across R127B, running the set at 117 VAC.

[old_coot88]

Originally Posted by Kamakiri

I'm at 45.8v across R127B, running the set at 117 VAC.

Kinda high. The current will be 196 ma. @8.96 watts. A 10W resistor will run sizzling hot.
196 ma. is the total current of the entire B supply going thru that resistor
What does the voltage across it drop to when you pull the 6BG6?

(Edit)
In a darkened room, does the 6BG6 show any sign of red plating?