Admiral 19A1, no vertical sweep (video attached)

[Jon A.]

Sorry to thread-crap Tim, but it seems that you haven't been reading (tracked) PMs, and I'm concerned about the remotes that you're forwarding to me. I just thought I would have heard something by now about what shipping will be for those and the other stuff. As long as you know where they are, I'm good.

[Kamakiri]

I've been really busy with other things around the house and haven't had chance to get them forwarded yet. I'll respond to you in a sec.

The set as it is uses 6 kV caps.....right now I have to figure out where one of the four tuner wires goes, and I can't do that without taking the drum out of the tuner and tracking the schematic. Gonna be cold and snow is in the forecast here for the week, so I may end up staying on this set for a bit. My Mouser order for another set won't be in until late in the week for my Zenith 23 H chassis.....

[Jon A.]

No prob, it's all good, I was just concerned that they may have been lost somewhere around there. Probably my OCD.

Anyway, I saw the video and was surprised that it was a mere 2-meg download. Following this thread for sure to see the conclusion.

[Kamakiri]

Well, now I've got this spare chassis in hand, and have figured out where all the loose wires go.

Attached them, and now nothing but a bright dot on the screen, no sweep whatsoever. I was able to blur it out with the focus control to the size of a quarter, but I couldn't even dim it down with the brightness control. Shut it off after about 30 seconds.

Why does it feel like I've taken a huge step backwards......

[RDusel]

Tim,
My 19A1 did not like GTB tubes. Caused problems with one of the sweeps (vertical I think). Putting in older GT/GTA tubes worked better.
I have the same set in almost working condition (it has some wiggling of the picture) if you need any wiring pictures.

[Kamakiri]

Maybe for vertical sweep, but I *did* have horizontal sweep before hooking up the one errant wire in the tuner, and before I realized that another wire was grounding out to chassis. The next step here is to pull the tuner drum and see what's going on with the wiring in there. I noticed that one of the wires inside the tuner was coming out the wrong hole, meaning that someone was in there fooling around at some point.

Did your set lose sweep entirely with the GTB tubes?

[Kamakiri]

Swapped the entire tuner assembly from a parts chassis with no change whatsoever.

I'm stumped as to where to start. When one wire was unhooked from the tuner and another was (possibly) grounded to the chassis, I had horizontal sweep, and audio of some kind. Now with the wires hooked up properly, and even subbing a different tuner assembly, I've got zero sweep of ANY kind (just a super bright dot, I had to pull it way out of focus and dim it of course), and zero out of the audio.

Thoughts?

[bigaudioal]

Good luck! Hope someone has some suggestions.

[Kevin Kuehn]

For the time being I'd leave the tuner out of the picture. Check that all your B+ voltages are correct, then focus on getting your horizontal and Vertical oscillators running first.

[Kamakiri]

Voltages are all screwy. I've got 295V on pin 3 of the 6V6 (should be 220VDC), and 261V on pin 4 (should be 200 VDC). Also showing 262V on pin 2 of the 6SL7 vertical output (should be 210 VDC). I've yet to find any negative voltage. Bear in mind also that my experience level isn't as high as a lot of you, but I'm learning quite a bit.

This set was a real hack job when I got it, so at this point anything could be suspect.

[kvflyer]

Originally Posted by Kamakiri

Voltages are all screwy. I've got 295V on pin 3 of the 6V6 (should be 220VDC), and 261V on pin 4 (should be 200 VDC). Also showing 262V on pin 2 of the 6SL7 vertical output (should be 210 VDC). I've yet to find any negative voltage. Bear in mind also that my experience level isn't as high as a lot of you, but I'm learning quite a bit.

This set was a real hack job when I got it, so at this point anything could be suspect.

High voltages on the plate of the 6V6 seem to indicate the tube is not conducting. The question is now why? How about the grid and cathode. Are they where they belong?

[old_coot88]

Can somebody post the schematic? The screwy voltages sound like the audio output stage is used as B+ dropper for the IF strip, tuner etc.

[Kamakiri]

http://www.earlytelevision.org/pdf/A...-sams-59-2.pdf

I can get back to checking the rest of the voltages, etc, tomorrow.....

[Kevin Kuehn]

Originally Posted by old_coot88

Can somebody post the schematic? The screwy voltages sound like the audio output stage is used as B+ dropper for the IF strip, tuner etc.

Yep. There's suppose to be 125vdc on the cathode (pin 1) of the 6AS5 audio output. 210vdc on the plate(pin 7).

[Kamakiri]

Everything seems to be running high. I've got 179 VDC on pin 1 and 286 VDC on pin 7.