Admiral 19A1, no vertical sweep (video attached)

[Kamakiri]

Definitely will! Wife and I take a LOT of road trips.....we usually combine our interests....she'll look up a Diners Drive-Ins and Dives restaurant, and I'll manage to work a TV in there

Nope, different set though.....this is a little 7" from the late 40s. The other one's a Sylvania Halolight.

I quit on the Admiral today, and I've got the RA113 on the bench, doing some more caps. Perfect day for it too.....20 degrees and windy with light snow outside. Wife is working (she does freelance transcription), and I'm all toasty in the basement with my soldering iron, my old Perfection kerosene heater, and a snoozing cat. Sundays were meant to be just like this

[Kevin Kuehn]

Can we assume the brightness control checked out OK, along with the 1M coming off it's center tap?

[Kamakiri]

Originally Posted by Kevin Kuehn

Have you've checked the brightness control, and the 1M resistor coming off it's center tap? The brightness pot is fed by the same B+ on pin 6 of the 6AS5. The voltage on pin 2 of the CRT should vary from 72-180v(according to Sams) with rotation of that control. Make sure you don't accidentally measure the HV with your VOM.

Resistor is measuring 1.13 M, so we're close anyway. Brightness control is within spec. Now, here's the odd part.

I noticed on the brightness control there is a wire that is attached to the terminal of the brightness control opposite chassis ground, that goes right to one half of C1.

My parts chassis does not have this wire.

The plastic on the end of the wire where it attached to the brightness control appears to have melted, and the wire was disconnected. Granted, it could have melted from the previous owner's soldering iron, but I get lost in the schematic right at that point trying to figure out if it should even BE there, as the junction spiders out everywhere.

[init4fun]

Originally Posted by Kamakiri

Definitely will! Wife and I take a LOT of road trips.....we usually combine our interests....she'll look up a Diners Drive-Ins and Dives restaurant, and I'll manage to work a TV in there

Nope, different set though.....this is a little 7" from the late 40s. The other one's a Sylvania Halolight.

I quit on the Admiral today, and I've got the RA113 on the bench, doing some more caps. Perfect day for it too.....20 degrees and windy with light snow outside. Wife is working (she does freelance transcription), and I'm all toasty in the basement with my soldering iron, my old Perfection kerosene heater, and a snoozing cat. Sundays were meant to be just like this

Cool , Sounds Great to me . If you are coming anywhere near Boston just give me a PM a day or two in advance so we can meet up . I am sincere in my offer of help when ya got a tough one , like I say I ain't God's gift to all things electronic but I do have a pretty good way with diagnosing and repair of our beloved tube sets .

[jr_tech]

From the Sams, it appears that the high end of the brightness pot should connect to C1-b. Does the wire indeed go to the "b" section of the cap? Perhaps the set that you are working on has a less obvious connection path... ohm it out, I bet the high end of the brightness pot is indeed connected to C1-b

jr

[Kevin Kuehn]

Agree with JR that the end opposite ground needs to be connected to + side of C1-B. You need that variable control voltage on the CRT's cathode(pin 2) in order to change brightness.

[Kamakiri]

Gotcha. I guess the parts chassis was more of a parts chassis than I thought.

I'll resolder the wire and proceed with the voltage test on pin 2 of the picture tube.

[Kamakiri]

Okay, now we're getting somewhere.....

Powered up after resoldering the wire, and shortly thereafter, a small POP....not big enough for me to shut the set down right away, but now I've got sweep of some kind FINALLY!

Same audio buzz is back in the speaker as in the video. High pitched whine coming from the chassis....I'm not sure if it's the horizontal oscillator going at warp speed, or what. Didn't see anything obvious in the POP, but I assume the next step is to start rechecking my voltages?

[Kevin Kuehn]

Yeah, you've at least got horizontal and vertical sweep now. It'd be interesting to see if your supply voltages came down closer to spec, now. From here it looks like you don't have horizontal lock, so that may be all that's keeping you from getting a stable picture at this point. Hard to say about the pop noise. Sometimes a control can arc if the riveted terminals are making poor contact with the resistance element, or the wiper itself could have poor contact. Does the brightness control appear to be working correctly now?

[Kamakiri]

Sure does! In fact, the set is now passing signal......I've got vertical lock, and perfect audio!

The horizontal is all messed up, though. There's a flat spot on the horizontal size control that's, well, most of the control. I'll ohm that out later and change it from the parts chassis if needed be.

Weirdly, the audio level is affected by the contrast control. I know in some of these sets, the circuits affect each other, is that the case here?

[jr_tech]

Yes! the contrast control varies the gain of the video amp, and the sound IF is driven off the plate of the video amp (through a 2 uuf cap) so contrast will affect the sound.

jr

[old_coot88]

The POP mighta cleared a tin whisker.

[Kevin Kuehn]

Originally Posted by old_coot88

The POP mighta cleared a tin whisker.

Good point. I've yet to find a control with a tin whisker, which I guess makes me a TV tech rookie.

[Kamakiri]

Here's where I'm at now

http://www.youtube.com/watch?v=7MkX8...ature=youtu.be

[Kevin Kuehn]

Looks like multiple foldover to me. Any chance you installed a cap that's off by a 10 factor? If so the horizontal osc could be running at some higher multiple frequency.