Help needed restoring a Murphy V310

[Heatercathodeshort]

Well done! That looks great. The ticking may be simply the line oscillator triggering at high EHT loading. I think you have cleared all the line timebase EHT problems.

With a fault like 'ticking' you really need to be hands on to hear what is exactly happening. It's very difficult over the Forum.

The picture will go negative with the contrast control full on or nearly so. This model does not have vision AGC. John.

[Boater Sam]

Listen with a length of plastic tube to locate the "tick"

[mark pirate]

There's always been a suspicion that tube is a bit duff and I may need to rejuvenate it.

The picture looks fine to me, I would now give the set some use for a few hours and watch a few programmes, it is very likely that the CRT will improve with use.

I only try to rejuvenate tubes that are very low, remember that there is a risk of killing it off completely!

Mark

[Radio_Dave]

I just can't find the cause for the top of picture twitch and ticking sound .

I'm now wondering if it's normal behavior for this set or it's because I'm setting up the picture controls wrong (more than likely!)

I've tried my hardest to take a video of the fault but the ticking sound has only recorded very faintly. The first half shows it up when I advance the contrast too far and the second half shows it when I advance the line hold.

https://www.youtube.com/watch?v=EaQPTfOI_O8


Regards
David

[Freya]

Is that being fed from an Aurora ?

Don't think it's a line hold issue

[Radio_Dave]

Originally Posted by Freya

Is that being fed from an Aurora ?

Yep

[1100 man]

Hi Dave,
I think you are chasing a fault that isn't there! 'Chasing fairies' my friend used to call it!

With several of my sets, as the line hold control is adjusted, the top of the picture starts to twitch just before it goes out of lock. You will probably find if you turn the control a bit further you will loose lock. The 'ticking' noise comes from the LOPT and is in time with the twitch.

There is usually a 'sweet spot' for the line hold control found by experiment. Different designs of timebase and sync separator behave in different ways: some can be more tetchy than others! I don't think you have anything to worry about.

The picture is looking pretty good now:- what does it look like with actual video content? Is the LOPT behaving itself now after all your efforts?

All the best
Nick

[Radio_Dave]

Originally Posted by 1100 man

Hi Dave,
I think you are chasing a fault that isn't there! 'Chasing fairies' my friend used to call it!

With several of my sets, as the line hold control is adjusted, the top of the picture starts to twitch just before it goes out of lock. You will probably find if you turn the control a bit further you will loose lock. The 'ticking' noise comes from the LOPT and is in time with the twitch.

That's what I wanted to hear

Originally Posted by 1100 man

The picture is looking pretty good now:- what does it look like with actual video content? Is the LOPT behaving itself now after all your efforts?

Video doesn't look as good I'm afraid. I seem to get those flyback lines back and I think I have a faint vertical white bar in the picture but I'm hoping (fingers crossed) it's coming from the ancient video recorder I'm using. The LOPTx is fine. It hardly gets warm after 45 minutes of use.


I have a feeling I'm not setting the controls around the back up right?


Regards
David

[1100 man]

"Video doesn't look as good I'm afraid. I seem to get those flyback lines back and I think I have a faint vertical white bar in the picture but I'm hoping (fingers crossed) it's coming from the ancient video recorder I'm using. The LOPTx is fine. It hardly gets warm after 45 minutes of use."

Hi Dave,
Good to know the LOPT is behaving itself! It would be interesting if you could post a video of actual video on your Utube channel so that we can examine the deficiencies and advise accordingly. By the way, I like your Uniselector Nixie tube clock- must have taken some time to build that! Also the cassette autochanger- only Philips could design that!

Out of interest, what video are you using?

Cheers
Nick

[Radio_Dave]

Originally Posted by 1100 man

By the way, I like your Uniselector Nixie tube clock- must have taken some time to build that!

Ha Ha! That's the most stupid thing I've ever made. The noise it makes is unbelievable!

I've quickly taken a video of it showing a movie. Unfortunately my camera has made a pigs ear of the recording it so please ignore all the flashes and lines and circles. You should be able to see the flyback lines, when I increase the brightness and the vertical white line in the right hand side of the screen.


https://youtu.be/UfNk124geJs


Regards
David

[Lloyd 1985]

That looks absolutely fine to me! It’s a feature of these old sets, I get flyback lines on most of mine if I have the brightness too high, just set it by turning it back until the lines disappear. The ticking in your previous video is normal too, definitely not arcing going on, I had it constantly on a Bush TV62 where the blocking oscillator transformer had gone OC, and someone had managed to work around it with a resistor and capacitor, the top of the raster would jiggle about and the lopt would be making that same ticking noise. Also my Ekco T161 does it when the line hold isn’t quite set, quick tweak stops it.

Regards
Lloyd

[Radio_Dave]

Thanks for positive reply. I need to stop messing about now, get it back in it's cabinet and start watching it!


There's only one thing left to do and that's to make a shield/cover for the U191 and 30P4 valves. I should be dead easy to do but I'm unsure if it needs ventilation holes in it. Does anybody know or maybe have a photo?


Regards
David

[1100 man]

I agree with Lloyd, that looks pretty good to me! I can't see any flyback lines at normal brightness setting. Trying to get absolute perfection from these things is a tall order- they all had shortcomings that were considered acceptable when they were produced. The designs were far from perfect!

I think the purpose of the LOP shield is to reduce RF radiation. I don't know how much use it is in the modern world where everything radiates RF hash anyway! A bit more from your TV probably won't make much difference.

However, I'll post some pictures of the one from my V410 if you want to make one. I assume it's probably the same?

Well done on what looks to be a good final result!

Cheers
Nick

[Radio_Dave]

Originally Posted by 1100 man

However, I'll post some pictures of the one from my V410 if you want to make one. I assume it's probably the same

That would be great if you could but please don't worry if it's too much trouble.

Regards
David

[Heatercathodeshort]

As I mentioned in post 161 the ticking sound is almost certainly due to the line oscillator triggering. The sound emanates from the LOPT amplified by the line output stage and resonating in the primary winding.[It's effect is rather like an old type telephone receiver insert]

Reducing the sync coupling capacitor to the line oscillator may cure your problem. I don't have the manual to hand but I'm sure you will find it. [Sync separator to line oscillator typically 10-20pf] Try halving it's value. J.

[Radio_Dave]

Originally Posted by Heatercathodeshort

Reducing the sync coupling capacitor to the line oscillator may cure your problem. I don't have the manual to hand but I'm sure you will find it. [Sync separator to line oscillator typically 10-20pf] Try halving it's value. J.

Would that be C307 on the circuit I attached in post #121?


Regards
David

[Heatercathodeshort]

It's C307 Dave, 12pf. Try reducing it to 5/8pf and see the effect of less sync coupling.
J.

[Radio_Dave]

Confession time! Looks like I had previously, mistakenly, replaced this cap with a 47pf. Now that I have reinstated the specified 12pf cap the picture does not twitch or make any clicking noises anymore.

Unfortunately the flyback lines seem to have gained two columns of bright dots which only vanish when I turn the brightness down even further than what's needed to get rid of the lines. This has only appeared since I changed the cap and made a cover for the U191 and 30P4.

I also still have a vertical white line that shows up well in the photo below. It's not shown up in the photo but the area to the right of the bar is slightly brighter than the other side as well.

Thanks
David

[Heatercathodeshort]

One down, one to go.
I would investigate the frame flyback suppression circuit. It comprises a low value capacitor connected from a sub winding on the frame output transformer to the first anode on the CRT. It's value is .002uf C90 Murphy circuit. Your picture is a bit confusing.
Check the capacitor is connected to the correct tag on the FOPT. John.

PS Shading may be caused due to lack of decoupling on the boost supply to the CRT A1. Check C111 .5uf and make sure it is connected correctly.

[Freya]

Check the source that's feeding the Aurora too, I had vertical line that was caused by a Humax freeview box.