10KV caps.

[Kevin Kuehn]

I think that picture looks wonderful on that old crt. I'm inclined to believe the video IF is about perfect, can't tell on the sound from here. I applaud you for taking the time to keep your trouble shooting skills sharp. I too feel that's a big portion of the enjoyment of getting these going. Routine replacing of caps is rather boring after you've done few million.

[JohnCT]

Originally Posted by Kevin Kuehn

I'm inclined to believe the video IF is about perfect, can't tell on the sound from here.

I forgot about the sound! I dismounted the speaker/transformer from the cabinet and plugged it in. There's only a bit of sound in a *very* small area of the fine tuning. Strangely, the FM works pretty good considering the only antenna is the one inch of twin lead on the balun transformer that's feeding the DVD player into the tuner input. It picks up half a dozen stations with no real antenna, although it's a bit distorted but listenable.

I haven't touched the sound section, but I suspect it will come around when I shotgun the rest of the caps and filters.

Originally Posted by Kevin Kuehn

I applaud you for taking the time to keep your trouble shooting skills sharp. I too feel that's a big portion of the enjoyment of getting these going. Routine replacing of caps is rather boring after you've done few million.

Man, I've had a blast so far. I've not spent any more than a half hour on any one session to make the fun last, and quite honestly I'm sure I'll be disappointed when it's all done and stuffed together. I've got a late 50s RCA metal portable that I'll have to do next.

It's not a sickness, is it??

John

[Electronic M]

Originally Posted by JohnCT

I forgot about the sound! I dismounted the speaker/transformer from the cabinet and plugged it in. There's only a bit of sound in a *very* small area of the fine tuning. Strangely, the FM works pretty good considering the only antenna is the one inch of twin lead on the balun transformer that's feeding the DVD player into the tuner input. It picks up half a dozen stations with no real antenna, although it's a bit distorted but listenable.

I haven't touched the sound section, but I suspect it will come around when I shotgun the rest of the caps and filters.



Man, I've had a blast so far. I've not spent any more than a half hour on any one session to make the fun last, and quite honestly I'm sure I'll be disappointed when it's all done and stuffed together. I've got a late 50s RCA metal portable that I'll have to do next.

It's not a sickness, is it??

John

You may need to walk the IF.... Basically tune the IF for max volume, shift fine tuning closer to best picture tune the IF for volume again till best sound and pix are in the same place.

The distortion could be ratio detector adjustment.

Definitely recap (and maybe check resistances) before playing with audio alignment.

Early post WWII TV stations used stronger sound carriers so TV and sets were not designed to have the same sound IF gain as 50s sets....It may end up like my Stromberg Carlson Dumont RA-103 clone where TV sound is adaquate with volume at max and FM radio is far beyond adaquate at a lower setting.

You got the affliction bad.... Just be glad it's TVs and not that other affliction going around.

[Kevin Kuehn]

If I'm not mistaken the sound is picked off just after the 1st video IF. If so there shouldn't be too much interaction with the video.

[Penthode]

Originally Posted by Kevin Kuehn

If I'm not mistaken the sound is picked off just after the 1st video IF. If so there shouldn't be too much interaction with the video.

In split sound sets there is interaction when fine tuning because the same front end local oscillator is responsible for the creation of the video if and sound if.

[JohnCT]

Originally Posted by Electronic M

You may need to walk the IF.... Basically tune the IF for max volume, shift fine tuning closer to best picture tune the IF for volume again till best sound and pix are in the same place.

The distortion could be ratio detector adjustment.

Definitely recap (and maybe check resistances) before playing with audio alignment.

Early post WWII TV stations used stronger sound carriers so TV and sets were not designed to have the same sound IF gain as 50s sets....It may end up like my Stromberg Carlson Dumont RA-103 clone where TV sound is adaquate with volume at max and FM radio is far beyond adaquate at a lower setting.

You got the affliction bad.... Just be glad it's TVs and not that other affliction going around.

A bad audio IF tube and weak output improved things, and I walked the audio IF as you suggested. Sound is very good but not all that loud - sounds like the way you described your SC..

Here's what's weird: when I put the TV/FM switch in the FM position, the screen of course goes dark but the TV sound gets considerably louder. I would be thrilled if the audio level was that loud when it's in the TV position. Note to those who are not familiar with this TV: the TV/FM function switch is NOT a bandswitch. This uses an infinitely variable Mallory "inductuner" (not a 12 position incremental type), so it tunes the FM continuously between VHF low and VHF high.

The TV/FM switch does several things: it lowers the B+, it disables the sweep by ungrounding the 6CD6 cathode, and turns off the filaments to the video section and CRT. It looks like it's supposed to also ground the -11V source at the bottom of the main bypass caps but that doesn't seem to happen, but then there are also a couple of changes made in my version than the SAMS I have for it.

All I did so far was disconnect the part of the switch that lowers B+ and the sound didn't improve, although the picture certainly deteriorated with the low B+.

I don't see how it could be the shutdown of the filaments because the increase of sound is immediate when put in the FM mode, and decreases immediately when it's put back in TV mode.

I'll play some more with it tomorrow.

Kramden66 was certainly right: this TV has a very good picture, better than I hoped actually.




The video IF definitely is a little off. When tuning from one extreme to the other, the picture is sharp on either side of center, but differently sharp (hard to describe it). One side has a bit of ring on vertical edges, the other a bit of noise. The center is free of artifacts but it has much less detail.

I mean, it's very good, but not optimal. When I'm finished done recapping and verifying the resistors, I'll do an alignment.

John

[Penthode]

I have had 5 decades aligning these early sets with split sound like yours. The distortion cannot be just the ratio detector because the sound IF in a split sound set changes with the fine tuning. Remember it isn't an intercarrier sound set where the sound carrier beats with the video carrier to maintain sound over the video tuning range. In a split sound set you adjust for best sound and the picture should and must be set at that point optimally. The sound tunes like an FM radio and when tuned you accept the video as is. This is why you need the proper equipment to do the alignment.

You need a sweep generator and accurate marker oscillator to align the video and audio IF. There is lots of literature on this. Follow the manufacturers notes.

I have aligned split sound Westinghouse, Dumont and RCA sets. (I currently have 4 pre-1950 RCA split sound sets). They all work superbly with full 4MHz video bandwidth and excellent sound. The alignment process is less forgiving but the picture quality is second to none when done right. And I prefer them as you do not get that intercarrier buzz!

Remember that the video is transmitted vestigial sideband and so the video carrier must be at 50% down on the nyquist slope. The picture when tuned correctly will be sharpest not brightest.

Seems to me you are almost there and hope to see you cross the finish line.

[JohnCT]

Originally Posted by Penthode

I have had 5 decades aligning these early sets with split sound like yours.

And I've got none. Attention being paid!

The distortion cannot be just the ratio detector because the sound IF in a split sound set changes with the fine tuning.

The distortion is gone. Bad cap in the ratio detector and a couple of cranky tubes. Also eardrummed the audio IF. The sound is nice and clear, no buzz, just a tad low in overall volume. Still, it's usable as is.

Remember it isn't an intercarrier sound set where the sound carrier beats with the video carrier to maintain sound over the video tuning range. In a split sound set you adjust for best sound and the picture should and must be set at that point optimally. The sound tunes like an FM radio and when tuned you accept the video as is. This is why you need the proper equipment to do the alignment.

I have several pieces of equipment and, unfortunately, none work at 24mhz that this old girl uses. I've been thinking of modifying my B&K415 (that I bought new). I aligned a few 44mzh TVs back in the 70s with that genny, and it's easy to use and works well.

I also took my VA48, set it to burst sweep, and fed its video output into a B&K1077B analyst (also bought new) and was able to have it convert the VA48 multiburst signal to 24mhz - the 1077 has an infinitely variable IF output.

I don't have the courage to try this hack setup on the Andrea, although I was considering just connecting it to the IF and scoping the video at the detector and see what the multiburst looks like. I may have something else of no value that I can use that frankensetup to experiment with.

I do have a Precision E-200 for which I only have a couple of crystals, but I don't know how accurate a wobbulator setup is.

Seems to me you are almost there and hope to see you cross the finish line.

Thanks. I planned to finish by the fall, and I'm way ahead of the schedule, so I backed off a bit for other projects.

What I really need to find is some sort of matching mahogany base to put it on.

Thanks for the info.

John