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Workshop Workshop Test Signals

 
crustytv
(@crustytv)
Vrat Founder Admin

Since work finished on my workshop back in November of last year, one thing I had neglected to sort out were my bench test signals. The rack I had before had been pulled apart and basically while working on a TV, I have to pull out the IMOGen or disconnect that and hook up the PM5509. A bit of a faff each time I wanted to switch from one to the other.

Today I finally got my finger out and connected everything up, so I have one RF cable to the bench with two combined signals, I can tune to 30 for the PM5509 & tone, and 56 for IMOGen/ Test card music. I'm monitoring the signals via a 5" Sony monitoring the PM5509 output, a 10" covering the IMOGen output, and finally a 5" TV for monitoring the RF signal.

OK, its hardly neat and I should probably make a box to house it all. I probably also need to go around and terminate a few connections, but for now it's a lot better than I've had of late.

signals
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Topic starter Posted : 17/06/2021 10:55 pm
ntscuser and Lloyd liked
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered

Either the burst is small or the syncs are big on that set of bars, Chris!

IIRC the "white" bar is in fact at 75% amplitude from a 5509 - so 525mV rather than 700mV?

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Posted : 17/06/2021 11:04 pm
crustytv
(@crustytv)
Vrat Founder Admin

Hi Mike,

I must admit that last time this 528A was hooked up it was with the much newer PM5515, this is the first time I've used the PM5509 and hooked it up to the waveform monitor.

This is your domain Mike, as a layman I thought a colour bar is a colour, is a colour bar, I no idea there were all these implementations of it, why would I. As such, I'm not familiar with what I should be exactly seeing on the waveform monitor,

The PM5509 Colour Bar has the White Horizontal bar across the colour bar

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This is the Courtyard CY420; "EBU ColourBar" (for those wondering, European Broadcasting Union, by the looks, an additional white bar at end?) selected, unlike the Philips on the Courtyard I can select 100%, 95% and 75%. Photo #2, top is PM5509 and below on the monitor EBU colour bar.

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Topic starter Posted : 17/06/2021 11:18 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered
Posted by: @crustytv

This is the Courtyard CY420; "EBU ColourBar" (for those wondering, European Broadcasting Union, by the looks, an additional white bar at end?) selected

20210617 232033[1]

Not quite, Chris.

EBU bars are described as 100.0.75.0 bars - that is, 100% luminance but only 75% saturation, which is why they have a 'dirty' look to them. You'll also note that the chroma doesn't go above peak white. 'BBC' bars - those on Test Card - were 100.0.100.25, which meant the chroma didn't go below black but were only 95% saturated.

The extra white bar after black was AFAIK a BBC 'mod' originally carried out to their colour bar generators so that the signal would show you where blanking started and stopped - otherwise with the black at the end of the sequence you'd not notice it. It looks like Courtyard adopted it 🙂

The display on the 528 from the Courtyard is *exactly* as I would hope to see (700mV of white, tip of green bar *just* touching black level), which does make me think there are "problems" with the 5509's output.

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Posted : 18/06/2021 12:02 pm
turretslug
(@turretslug)
Honorable V-Ratter Registered

How nice to see a 528A in action again, a workhorse of the broadcast industry from Tektronix' glory years before the mechanical construction aspect got seriously pared down. I reckon you should try to get hold of its contemporary partner vectorscope, the 1421, then you'll have an excuse to throw the word "goniometer" into conversations.... I do regret not getting examples of these and something like a Tek or GVG TSG at the time that they were being cleared out en masse, but it was at a time when I was trying to clear "stuff" out of my life, rather than acquire more!

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Posted : 18/06/2021 6:23 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered
Posted by: @turretslug

How nice to see a 528A in action again, a workhorse of the broadcast industry from Tektronix' glory years before the mechanical construction aspect got seriously pared down. I reckon you should try to get hold of its contemporary partner vectorscope, the 1421, then you'll have an excuse to throw the word "goniometer" into conversations.... I do regret not getting examples of these and something like a Tek or GVG TSG at the time that they were being cleared out en masse, but it was at a time when I was trying to clear "stuff" out of my life, rather than acquire more!

Might be able to help you out there....

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Posted : 18/06/2021 6:39 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posted by: @turretslug

I reckon you should try to get hold of its contemporary partner vectorscope, the 1421, then you'll have an excuse to throw the word "goniometer" into conversations....

I do have a 1421, unfortunately its internal sub carrier has a fault, I've never been able to get it to lock up or find the fault. I bought the Courtyard to provide the 1421 with an ext sub, but I couldn't get that to work with it either. Utter failure, I know. The vectorscope would have come in handy when I get to the G6 decoder alignment, I'll just have to settle with the oscilloscope.

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Topic starter Posted : 18/06/2021 7:00 pm
turretslug
(@turretslug)
Honorable V-Ratter Registered

@cathovisor Thanks for the thought, but I can't honestly say that I "need" a 528A (or a 1421!), in the end a 528A is a specialist 'scope in effect with limited utility for anything else, a 1421 is an unusual and even more specialist device that would only be "interesting clutter" of which I have enough as it is! As long as there are a few still around for posterity. I suppose a 1781R with probe option would be the ultimate plaything in this field, comprehensive but complex. From the few that I worked on, I recall that the "cleverness" was pretty reliable but PSU/EHT problems were starting to show up with age.

@crustytv I'm reminded now of the 1421 vectorscope post that you did now, thanks for that pointer. I even commented on it at the time! I guess that the grey matter doesn't cling onto everything nowadays.

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Posted : 11/07/2021 5:53 pm
Katie Bush
(@katie-bush)
Illustrious V-Ratter Moderator
Posted by: @turretslug

I guess that the grey matter doesn't cling onto everything nowadays.

Ha, Haa,  Like a greyscale, It starts out strong at one end, and fades out to white at the other!

Fade To Grey. . . . . .

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Posted : 11/07/2021 7:51 pm
Alex728 liked