Ghosts in my Crosley Machine - Videokarma.org TV - Video

Chris K · #1 01-10-2024, 05:37 PM

My model 9-413B that I had the horizontal issue with before. I have lock and I'm happy with the positioning and focus. But what is this negative image on 2/3 of the screen?

As always, ignore the blanked out section. Does anyone know what this is? I have not an alignment or anything other than adjust the horizontal frequency, the yoke and focus coil positioning.

Stumped...as usual.

Electronic M · #2 01-10-2024, 06:26 PM

How does it look with normal program content? The crosshatch makes it difficult to tell if the horizontal is syncing centered or out of phase with the sync pulses...
I've seen similar effects where the horizontal hold was adjusted so out of phase the H sync blanking bar was mid screen and the picture info was ringing into the sync blanking...And it looked a lot like that.

Chris K · #3 01-10-2024, 08:13 PM

This is RF video sent from a converter box into the antenna. The bottom is sync blanked but the image...much better in person, has all of these wavy lines from the top of the screen to the bottom.

The Crosley uses the Mallory continuous tuner like the RA-103 Dumonts. If I tweak the tuning, I can almost get rid of all the wavy lines but it's obvious it's off channel. The sound buzzes like crazy. Is this a tuner issue and I've been chasing my horizontal tail all over the place?

Penthode · #4 01-10-2024, 08:38 PM

The Dumont is a split sound design? Do you understand the difference between split sound and intercarrier designs? There is a lot of literature. Here is and earlier Videokarma post
https://www.videokarma.org/archive/i.../t-251212.html

The ringing is most likely due to the RF local oscillator off. The split sound design you adjust the fine tuning control for best sound, not best picture and the best sound adjustment is fairly critical.

Try adjusting the local oscillator or fine tuning to bring in the best sound. Once you have the best sound, the picture should be optimum if after all these years the IF alignment is intact. Generally the alignment will be off especially if you have replaced parts or even replaced tubes or redressed the wiring in the Video IF stages.

But get the local osciallator on frequency first. If the RA103 has a tuning eye tube, that would be used for optimizing the fine tuning for best sound.

Chris K · #5 01-10-2024, 08:58 PM

Yes I'll have to do a full alignment on this. I tweaked the 1st video IF coil and that got rid of the waviness. It has a very good picture now. The issue is the misalignment, or the lack of being in the same place on the dial for sound and picture. Looking at the Crosley schematic right now and I see what you are talking about with the "split".

Electronic M · #6 01-11-2024, 01:40 AM

Quote:

Originally Posted by Chris K

Yes I'll have to do a full alignment on this. I tweaked the 1st video IF coil and that got rid of the waviness. It has a very good picture now. The issue is the misalignment, or the lack of being in the same place on the dial for sound and picture. Looking at the Crosley schematic right now and I see what you are talking about with the "split".

Penthode will probably strongly dislike the following, but here goes...

That Crosley is basically a paired down Dumont RA-103. I've had several RA-103 sets and sound was out to lunch on most of them (completely out of range of any video). Lacking any equipment for sweeping the old 21MHz IF what I did was tune in good sound, adjust fine tuning towards the video to the edge of distinct sound, peak the sound IF by ear, walk the tuning towards video some more and repeat until I have best sound at the point where on a Philips PM5544 test pattern video looks best (the multi burst pattern and chroma dot crawl on the color patterns as well as lack of ringing on the center crosshatch make best video easy to determine).

It's not the "RIGHT" way to do it but it does work well enough that if all 4 of the RA-103s I have fixed were in a room running none of you would be able to guess which one still has its original alignment working undisturbed.

You can choose any method you want on your TV. I'm just explaining what I do with what I have.

Chris K · #7 01-11-2024, 06:38 AM

I have an Eico sweep generator that will get down to 21MHz but I haven't used it on a project yet. I bought it, restored it and had custom probes and cables made for it so I could align the early TVs but I think I should at least try a low tech method first.

Penthode · #8 01-11-2024, 10:24 AM

Quote:

Originally Posted by Chris K

Yes I'll have to do a full alignment on this. I tweaked the 1st video IF coil and that got rid of the waviness. It has a very good picture now. The issue is the misalignment, or the lack of being in the same place on the dial for sound and picture. Looking at the Crosley schematic right now and I see what you are talking about with the "split".

Eeek. The IF adjustment you should not have touched. You need to set the baseline reference which is getting sound tuned in by correctly setting the RF Oscillator. The tuning will behave like an older FM radio with discrimator detector: eg nulls either side of best sound. You adjust the RF tuning to get best sound. If lucky, when yopu adjust for best sound, you may adjust the first IF back to where it was.

The set is capable of providing a highly resolved full bandwidth picture. But the only way to achieve it is to ensure it is properly aligned. My suggestion I think is the best but if you are will to compromise with less than optimal performance you may fiddle around until you get some sort of a picture.

Chris K · #9 01-11-2024, 10:44 AM

So I should use the tuner to get good sound and then get the best sound by adjusting the RF unit to get the sound to optimal?

Then move down the video IF and adjust to get the picture optimal and coordinated with the sound?

Penthode · #10 01-11-2024, 07:33 PM

Quote:

Originally Posted by Chris K

So I should use the tuner to get good sound and then get the best sound by adjusting the RF unit to get the sound to optimal?

Then move down the video IF and adjust to get the picture optimal and coordinated with the sound?

I would suggest first tune the rf oscillator to get best sound, return the first IF adjustment close to where it was and then assess the situation.

If their was evidence of repair work in the past, someone may have tweaked the IF. You may be lucky and find the response not bad and only some minor tweaking is required. But after 75 years, it would be useful going over the alignment.

Do you have an accurate rf frequency generator? I have used mine to determine if the discriminator zero setting is still on frequency and the traps are still set to frequency. Checking the discriminator zero cand be done with an unmodulated rf source set to the sound IF frequency loosely coupled to the first Sound IF stage.

Tune the generator back and forth across the manufacturers setting and either use your ear or a VTVM to find the null. Unless it has been monkeyed with in the past it should be close to spot on. Next loosely couple the generator modulated with say 400Hz to the rf mixer and tune the generators across the trap frequencies and see if you can see the dips on the crt screen. That is my preliminary test with these sets.

A couple of years ago when I resuscitated my 1947 RCA 72TCS, I did the same and found the alignment pretty close. I nevertheless did a full alignment to obtain the manufacturer's response. The RCA is a cheaper set with only three video IF stages and with an overall video bandwidth of only 3MHz, yields pretty good pictures. Yours with four stages should be better.

Penthode · #11 01-12-2024, 08:20 PM

I should add that you should never touch the IF adjustment unless you have the proper test equipment or know precisely what you are adjusting.

When completing a video IF alignment of a split sound receiver, I would run a signal through the set and assess the picture when tuned to best sound. I examine the video quality and may slightly improve it (making the video slightly softer or sharper) by ever so slightly adjusting the appropriate stagger tuned IF transformer or coil which most affects the placement of the video carrier on the IF slope. If after adjustment the picture is satisfactory I may just leave it or again re-examine the swept IF response to see precisely where on the slope the carrier is. It may often be best at 40% to 45% instead of the nominal 50%.

However outside of that range if the picture remains soft I begin looking at the peaking coils and detector and Video Amp load resistors. If the resistors have drifted upward, they make the picture soft. The peaking coil may be open leaving only the shunt resistance in circuit. On at least three instances I have found the wrong value peaking coil installed likely due to amistake in manufacture!

Chris K · #12 01-21-2024, 12:19 PM

I wish you didn’t live in Canada! I’d drive it to you!

Penthode · #13 01-22-2024, 09:02 PM

Where are you?

Chris K · #14 01-23-2024, 01:47 PM

Pennsylvania USA

Chris K · #15 01-23-2024, 01:53 PM

Near Philadelphia. Not really really far but far enough. If there was a way I could get it to you without the 10BP4, I'd entertain shipping it and paying for both ways but I don't know. You can PM me if anything like that interests you.