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Old 10th Oct 2022, 12:57 pm   #41
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Default Re: Ultra BRC 1500

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Originally Posted by bionicmerlin View Post
So far I put a new 30FL2 valve in and bridged C53 . Practically no change .
Going back to Transistor VT10 . There is two voltage reference points on the 1500 diagram.
I believe on point C it should be 44volt I’m getting 178 volt
On E it should be 1 volt . I’m getting 0V
I stupidly left my AVO at work so I’m using digital. Even so that voltage can’t be right.
Is it best to try a new Transistor . I will have to get one.
Thanks everyone Andy
From those voltages VT10 is turned off or open circuit between base and Collector or base and emmiter.
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Old 11th Oct 2022, 1:38 am   #42
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Default Re: Ultra BRC 1500

Made a bit of progress. R61 had almost doubled in value. I have changed that and now the Line hold locks displaying a picture. Not a good picture but as it was getting late it was time to make that do for tonight. Hopefully I will get back to it later Andy
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Old 11th Oct 2022, 12:18 pm   #43
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Default Re: Ultra BRC 1500

For the poor picture I would check the value of the two feed resistors to the collector of the Video Output transistor. We use to change both and use one 3.3k and one 3.9K. One watt or half watt resistors will do. Also check the high value feed resistor to the focus control and the value of the focus control itself.

That Unitra tube might be a replacement or regun tube fitted when the original failed. With a mechanical tuner your set would most certainly have had a Mazda tube fitted. The last versions of the 1500 which used electronic or varicap tuning could have had the Unitra tube fitted as new.
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Old 12th Oct 2022, 2:10 am   #44
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Default Re: Ultra BRC 1500

Simon . I have checked all 3 of those resistors and they are less than 10% out. Unless you think I should change them anyway.
I’m not making much progress . The picture is not good. Difficult to describe.
Picture very jerky not through frame slip.Tends to expand then contacts. Pulls and every now and then white diagonal partial fly back type lines appear but not all the time. Edges very fussy especially the verticals.
Andy
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Old 12th Oct 2022, 9:38 am   #45
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Default Re: Ultra BRC 1500

Two things spring to mind. Firstly signal overload - try some attenuation first.

Secondly decoupling. Any of those black Callins capacitors in there still?

Also you mentioned you have changed the main electrolytic with separate capacitors. Remind me of the original's values in case I have a NOS one around somewhere.
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Old 12th Oct 2022, 10:29 am   #46
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Default Re: Ultra BRC 1500

What about the sync separator feed resistor? R44, 47k. That would cause iffy sync. Could also be C37 video coupling cap. Give them a try.
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Old 12th Oct 2022, 11:13 am   #47
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Default Re: Ultra BRC 1500

Intermittent pulling effects and picture size fluctuations can be caused by poor dag connections.
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Old 14th Oct 2022, 1:04 am   #48
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Default Re: Ultra BRC 1500

Thanks everyone . I haven’t had much time but . The dag was not that good ,sorted now,
R44 has already been replaced. I did check C37 it tested fine but I replaced it anyway.
All the callins have been replaced, I have tried a variable attenuator .
After trying all these things it’s just the same. .
The main cap is 150 x 150 x 100.
I will hopefully have a bit more time over the weekend Andy
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Old 14th Oct 2022, 11:21 am   #49
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Default Re: Ultra BRC 1500

It could be a hum bar problem. As you have checked everything it may be the main smoothing can. Are you still getting those voltages around VT10?
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Old 16th Oct 2022, 2:15 am   #50
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Default Re: Ultra BRC 1500

Well . Some slight progress. But only slight. As I was scratching about I found C89 open circuit. On replacing I found the picture or frame wouldn’t come on at all. Coincidence I would think. I then replaced PY801 . That has sorted out the frame problem and now the picture appears in normal time not like before when it took ages. . I also get a fuller picture but still very fuzzy and jerks.
Simon I did test the voltage on VT10 Again I’m now getting 106volts on C and .7 volts on E

Andy
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Old 17th Oct 2022, 10:49 am   #51
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Default Re: Ultra BRC 1500

Sounds like good progress is being made. The Collector voltage of VT10 still a bit high. I will try and dig out my 1500 manual and take a look. I am at work at the moment but will try and do it one night this week.
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Old 17th Oct 2022, 2:23 pm   #52
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Default Re: Ultra BRC 1500

Ok Simon no hurry .thanks Andy
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Old 4th Nov 2022, 5:17 pm   #53
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Default Re: Ultra BRC 1500

Back again after a bit of a break.
I have improved on things by about 90% just
By fitting a NOS tripler that’s sorted out the jerky and poor picture to a degree.
I got some pulling on the verticals and besides that the brightness and contrast is on full . A bad tube I would assume. Sound has still got more hum than it should have . I’m probably limited to what I do if the tube is iffy Andy
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Old 4th Nov 2022, 5:17 pm   #54
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Default Re: Ultra BRC 1500

Woops it’s not really that way up Andy
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Old 4th Nov 2022, 6:14 pm   #55
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Default Re: Ultra BRC 1500

That is possible, especailly if the smearng on the left increases with contrast and/or brightness. However give it a really good soak test and who knows?
Now you need to scavenge some proper knobs...
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Old 4th Nov 2022, 8:03 pm   #56
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Default Re: Ultra BRC 1500

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Now you need to scavenge some proper knobs...
Well I have a matching set of three on the nicotine-stained Ferguson shown on page 2 of this thread which I would happily donate to the cause as sadly that tv is pretty much scrap. By coincidence I have another BRC set missing one knob which is of exactly the type Andy has on his brightness control. Maybe we could do a swap...

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Old 6th Nov 2022, 3:06 pm   #57
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Default Re: Ultra BRC 1500

Glyn .
The set has been on for several hours now. The brightness has slightly improved . The smearing on the left has got better. But it gets worse when the brightness is turned down. The picture does also tend to pull to the left the more I turn it down . The picture is very watchable although not perfect.
I still have this hum. It disappears when I remove the signal source. The detector balance is turned fully one way and if I turn it the other way it gets worse.
The frame hold is a little touchy on warm up .
Steve . I been looking through my knob box and don’t have a set . Can I take you up on your offer. The one you want on my set is got a black insert with white paint on. If that’s not the one I got one with a copper insert the same . PM me if you like Andy
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Old 6th Nov 2022, 9:12 pm   #58
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Default Re: Ultra BRC 1500

Hi Andy

That's great I'll send you a PM for your address and will get those control knobs on their way to you once I've cleaned them up.

The knob I'm after, which I think is the one on your set, is as per the photo attached. It has a black disc insert at the end.

I don't want to distract from your thread, so back to the plot!

Steve
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Old 7th Nov 2022, 12:12 pm   #59
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Default Re: Ultra BRC 1500

Does that smearing effect on the left vary if you adjust the horizontal hold?
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Old 8th Nov 2022, 6:12 pm   #60
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Default Re: Ultra BRC 1500

The picture pulling can happen when the contrast is set too high. Check the adjustment of the preset contrast control and/or turn the contrast control down a little to see if the problem improves.

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