Royalmont (Marconi) 735K23 - Need Help

[SkyLlama]

I bought this set and another for 60$ and this was in the best shape between the two so I decided to give it a go.

This is my first TV project, and this TV by all accounts is a fairly simple B&W set from I think the mid 60s.

The CRT is good for sure, the tubes I don't have anyway to test at the moment (but I have a ton of spares I can swap out) and everything except the caps and a few resistors are fine.

It did "run" before I recapped it and after I recapped it it still does, but nothing, nothing at all has changed about how it's running. You'd never know it'd been recapped.

I made a mistake in the cap order and was two caps short, but I found a few in some old parts I had for the time being.

All you get is a lit up screen and lines from top to bottom that make a sort of "strobing" effect.

I was once able to get static and sound, but no image and the tuner was incredibly finiky.

This image is what I see every time I turn it on, no matter the channel.



In this photo you can clearly see the lines the cause the sort of "strobing effect", plus what happened when I plugged the Beta player into the TV. The Beta player did effect the screen, but this is all it did.



In this video you can see the only time I managed to get static, the one time I got sound to come out of the speakers and the fact the video output diden't change at all. (how on earth do you have sound and not some effect on the image for the signal?)

IT's very loud at first! Turn down your sound!

https://www.youtube.com/watch?v=b3U5bFVzsbk

Any ideas on what's up? I know I've got no clue at all, because TVs are new to me.

[Eric H]

First thing I see is the deflection yoke is turned 90 degrees, the scan lines should go from side to side, not top to bottom. That won't affect the video however.

Since you have sound the problem has to be somewhere after where the audio is split from the video, it could be as simple as a bad video output tube or the circuit supporting it.

[dieseljeep]

Just as a side note, I worked on two Royalmonts the ended up Milwaukee.
They appeared to be Canadian Admirals. Weren't they an Eaton's product line.
I saw those, but never an Andrea, which is an eastern US make.

[SkyLlama]

Originally Posted by Eric H

First thing I see is the deflection yoke is turned 90 degrees, the scan lines should go from side to side, not top to bottom. That won't affect the video however.

Since you have sound the problem has to be somewhere after where the audio is split from the video, it could be as simple as a bad video output tube or the circuit supporting it.

Eh, fix that. Just a stupid beginners mistake I guess

I found a spare 6aw8a and substituted it in with no change. The tuner at this point seems to have absolutely no effect on the TV. I did manage to get sound and static once, but never since.

Just as a side note, I worked on two Royalmonts the ended up Milwaukee.
They appeared to be Canadian Admirals. Weren't they an Eaton's product line.
I saw those, but never an Andrea, which is an eastern US make.

Hum, I don't know. This TV is surely made by Marconi though. Evey single thing in it has their name on it, plus it says so on back

[Electronic M]

Tuner contacts could be dirty/corroded which could account for it not wanting to pass any signal.

If the lines change with video (ie. if you have still frame the lines don't change, and with moving video moving lines) then the video is probably fine and the horizontal oscillator is likely way off frequency.

You could also have open video peaking coils after the sound take off if there is truly no video.

PS: I have two of those Beta decks. They are amazingly reliable for plane-jane decks.

[bgadow]

I would start by finding the AGC control and turning it. If that doesn't change anything, do what Tom says and check the tuner. Often if you jiggle it enough you can get some action. After that, jiggle every tube in the tuner/IF/video circuits, and if still no luck swap each of them out.

I once had a brand new 300-75 ohm coax adapter that was bad out of the package, and it produced results like this.

[SkyLlama]

I'll have to take a closer look at the tuner and see if anything is up there. I turned the AGC and nothing. The one time I did get sound it was due to a lot of jiggling things around and and getting stuff in just the right spot.

After that I guess I move onto messing about with the tubes. I almost had a tube tester the other day, but alas someone bought it just before I did.

@Electronic M - Indeed they are good decks. I've not had any issue with that one

[electroking]

Canadian Marconi had its own factory until about 1965-1966, I don't believe they
ever marketed TV sets made elsewhere. They did sell Japanese made transistor
radios though. Good luck with this project!

[BigDavesTV]

I completely agree with Electronic M, and bgadow, plus, check to make sure the correct tubes are in their correct sockets! If wiggling the tubes doesn't help, look for a cracked circuit board, or cracked, cold solder joints on the board and on the tube socket pins, where the pins solder into the board. Also look for cracked, open solder joints where the board grounds solder to tabs on the chassis metal frame. If these are all OK, try swapping the tubes in the tuner & IF sections. Hope these thoughts help, these are things I've experienced over the years, best of luck on your restoration!

[electroking]

I trust this set uses point-to-point wiring, no printed circuits. Can you confirm, SkyLlama? Regards.

[SkyLlama]

Originally Posted by electroking

I trust this set uses point-to-point wiring, no printed circuits. Can you confirm, SkyLlama? Regards.

Yep, it's all point to point stuff.

When I get sometime tomorrow I'm going to go over all the stuff you guys have mentioned.

[Jon A.]

Pretty sweet-looking old TV, best of luck getting it going. Looks like you have a good start, from another beginner's point of view. Nice Beta deck too.

[SkyLlama]

Went to work on it today and have a loot at stuff and while messing about a resistor broke right it half! I barley touched it at all. I found a spare of the same value a put it in and all is good, but I've never seen that happen on anything I've worked on before.

I don't a lot of what you guys have said with no luck, but I'm going to keep trying! The next thing I plan to do is put in some other tubes and see what they do.

[SkyLlama]

Okay so I've not been able to sleep (4AM !) and I went to mess around with the TV some more and some very weird that I can't explain happened, that I've been able to reproduce several times.

The TV up until now was just doing the same thing displaying no image on screen and all I could get was a faint hum from the speaker. The tuner appeared to be doing nothing for the set at all.

Then I plugged in the Betamax player again and suddenly I had static from the sound (I coulden't get a good look at the image because of cramped working space) on three channels. All other channels still give nothing and a faint hum, but those ones ( I think 2,3 and 4) produced static only when the Betamax player was connected.

I think I've narrowed down where the issues might be, but I'm just onder if that make sense to anyone else?

[bgadow]

Have you subbed the tubes in the tuner? Have you cleaned the tuner?