Advantest R3265A Composite Video Out

[neuschs]

Good day,

Because I nearly completely stripped and rebuilt one of my Advantest R3265A, I wanted to try to replace the quite burned CRT for an LCD Panel...
So I tried the so called "Composite Video" Out at the back with a few different Video to HDMI converters or directly driving the LCD Panel Driver chip.
But I always have synchronization issues, so the picture runs from left to right. I tested those adapters with an old VHS player and a PS2 and they work well.
The manual of the spectrum analyzer calls it "composite video; 1V p-p; 75 Ohm". Attached is the circuit diagram of the output stage - maybe someone with experience in analog video can tell by the design, which protocol/electric standard is used in this case. There are some scope pictures of the signal.
Also a video of the "running" video in the 7z file.
My ultimate goal is to have it running on usual composite video lcd panel.

Thanks for any help or feedback in advance.

[wasedadoc]

I see nothing wrong with the waveform timing.  Horizontal sync pulses at or close to every 64 us.  But amplitude is suspect.  The universal standard for composite video is 1 Volt peak to peak into 75 Ohms.  Sync amplitude 0.3 Volt. Peak white 0.7 Volt.  The ratio of those looks OK on your scope but the millivolt markings appear to mean the signal is much too small.

The circuit appears to use the conventional method of an emitter follower to give low impedance and then a series resistor close to 75 Ohms.  2 Volts peak to peak at the emitter then gives 1 Volt p-p into the 75 Ohm termination in the display.

What does the scope show on the emitter?

[neuschs]

I can measure it tomorrow, but I now realize, that I had the 10:1 attenuation active on the probe (I measured on a 75 ohm resistor with the normal 10MOhm probe).

[wasedadoc]

I can measure it tomorrow, but I now realize, that I had the 10:1 attenuation active on the probe (I measured on a 75 ohm resistor with the normal 10MOhm probe).

In which case the amplitude is well within the range that a display should sync to.  Can you try directly to a display with composite input?  Even modern TVs still have one.

[Benta]

Signal looks fine. But I have reservations about your CVBS/Composite to HDMI adapters.
Real ones are rare and expensive (100...200 Euro) and contain a lot of electronics. The adapter plugs you can buy in the local store you can forget completely.
Do what wasedadoc says and plug the signal into the yellow RCA/cinch receptable on your TV. That should work.

[neuschs]

Hm, if you can recommend one I would be interested into some recommendations.
I have no access to a TV with an composite video input. That is actually the reason why I have such a adapter around.

[wasedadoc]

Hm, if you can recommend one I would be interested into some recommendations.
I have no access to a TV with an composite video input. That is actually the reason why I have such a adapter around.

No access to a TV or no access to one with a "yellow RCA phono socket"?  Do you have access to a TV with SCART socket(s)?  Every one of those has composite input.

[Benta]

There are plenty of VGA -> HDMI adapters around (eg, https://www.conrad.de/de/f/vga-auf-hdmi-adapter-1914662.html), but whether they'll work with old-fashioned 15625 horizontal is an open question. I don't know, and they don't say.

[vk6zgo]

Signal looks fine. But I have reservations about your CVBS/Composite to HDMI adapters.
Real ones are rare and expensive (100...200 Euro) and contain a lot of electronics. The adapter plugs you can buy in the local store you can forget completely.
Do what wasedadoc says and plug the signal into the yellow RCA/cinch receptable on your TV. That should work.

The horizontal syncs are bit excessive in duration, but that shouldn't matter much.
I really hate the 'scope display, with all the extraneous extra stuff.

All that is needed is a display of the voltage levels at the various standard video references--blanking level, sync tips, & peak white.
The same applies to the timing intervals.
Multiple display of intermediate values just makes things confusing to those of us who don't own that particular style of DSO.

At this point, a photo of the effect on a monitor may be helpful ---does "runs from left to right" mean the pix is continually losing horizontal sync, or that the lines are locked, but progressively further left?

I'm wondering if the problem is that the "composite" video out of the R265A is not interlaced, but simply "progressive scan".

Old style analog monitors were quite forgiving & would pretty much sync to even the most non-standard video, but the converters & even the composite input of modern monitors need to convert the sync regime to HDMI or to their "native" standard, so have some way of correcting for the half line offset on "odd" fields.
If there isn't one, they may "get a bit confused".

[neuschs]

I will try to find a monitor and test it there.
In my first message is a 7z with a video file showing the results.

If you are not used to this view and scope and you think you can help me further, I can create a "cleaner" picture. My intention was to show the position of one part in a longer transmission.

[vk6zgo]

I will try to find a monitor and test it there.
In my first message is a 7z with a video file showing the results.

If you are not used to this view and scope and you think you can help me further, I can create a "cleaner" picture. My intention was to show the position of one part in a longer transmission.

If you just look at one or two lines using all of the available screen area both in time & amplitude, it will be easier to see.
I don't know if this is possible, but it would be nice if you could simply display the duration of the line syncs, & the line duration, as well as the blanking to sync amplitude & the blanking to peak white amplitude, without all the intermediate values.

 In standard PAL, SECAM & NTSC video wave forms, the blanking level should be at zero volts, with the syncs negative of that reference, & the actual video positive.
The devices you are feeding your video to may be "fussy" about this.

It may be interesting if you can display two video fields, with the 'scope set to 10ms/div.
(Some DSOs will give an unusable display if you try to do this, as their sample rate drops too low to reproduce the high frequency components of the analog video signal.)

The reason I suggest this, is so you can see if the video signal has "odd" & "even" lines or if all the field syncs are identical.

[wasedadoc]

In standard PAL, SECAM & NTSC video wave forms, the blanking level should be at zero volts, with the syncs negative of that reference, & the actual video positive.
The devices you are feeding your video to may be "fussy" about this.

Composite video outputs are frequently AC coupled and I have never encountered any video equipment - broadcast or domestic - which required the input video to be at a fixed DC level.  It is not correct to write "the blanking level should be at zero volts".  It is correct to state syncs negative and video luminance positive.

If the OP's probe was set to x10 but the scope set to x1 then the displayed levels are OK.

[vk6zgo]

In standard PAL, SECAM & NTSC video wave forms, the blanking level should be at zero volts, with the syncs negative of that reference, & the actual video positive.
The devices you are feeding your video to may be "fussy" about this.

Composite video outputs are frequently AC coupled and I have never encountered any video equipment - broadcast or domestic - which required the input video to be at a fixed DC level.  It is not correct to write "the blanking level should be at zero volts".  It is correct to state syncs negative and video luminance positive.

They are not commonly ac coupled in Studio type Broadcast TV equipment in Australia.
My comment did say "the equipment may be fussy.

In any case, it is convention if displaying analog video on an Oscilloscope, to set the blanking level as the reference point from which the syncs are positive & video luminance positive.

I have "looked at more video waveforms that I have had good breakfasts", but they were mostly with waveform monitors or analog 'scopes, where the former had the voltage levels for blanking, sync tips & peak white emphasised, & the latter with just a normal graticule.
The advantage of analog Scopes is that you can adjust the position of blanking level to a convenient graticule marking.

If the OP's probe was set to x10 but the scope set to x1 then the displayed levels are OK.

Yes, but as I pointed out, the display is messy & hard to decipher when you don't have the actual DSO in front of you.
I could have said, "OK, I scrunched my eyes up & finally determined that the levels were right" but thought my suggestions might give the OP a better idea of how to display such signals.

I also suggested trying to display two fields, just in case the converters "are too clever for their own good" & are getting confused if the video is in fact sequential, not interlaced.

[wasedadoc]

In standard PAL, SECAM & NTSC video wave forms, the blanking level should be at zero volts, with the syncs negative of that reference, & the actual video positive.
The devices you are feeding your video to may be "fussy" about this.

Composite video outputs are frequently AC coupled and I have never encountered any video equipment - broadcast or domestic - which required the input video to be at a fixed DC level.  It is not correct to write "the blanking level should be at zero volts".  It is correct to state syncs negative and video luminance positive.

They are not commonly ac coupled in Studio type Broadcast TV equipment in Australia.
My comment did say "the equipment may be fussy.

In any case, it is convention if displaying analog video on an Oscilloscope, to set the blanking level as the reference point from which the syncs are positive & video luminance positive.

I have "looked at more video waveforms that I have had good breakfasts", but they were mostly with waveform monitors or analog 'scopes, where the former had the voltage levels for blanking, sync tips & peak white emphasised, & the latter with just a normal graticule.
The advantage of analog Scopes is that you can adjust the position of blanking level to a convenient graticule marking.

If the OP's probe was set to x10 but the scope set to x1 then the displayed levels are OK.

Yes, but as I pointed out, the display is messy & hard to decipher when you don't have the actual DSO in front of you.
I could have said, "OK, I scrunched my eyes up & finally determined that the levels were right" but thought my suggestions might give the OP a better idea of how to display such signals.

I also suggested trying to display two fields, just in case the converters "are too clever for their own good" & are getting confused if the video is in fact sequential, not interlaced.

I too have spent years looking at analogue video waveforms and designing video equipment to broadcast specs.  I don't dispute that broadcast gear often has +ve and -ve power rails which permits the output stage to be biased such that it does not require an output capacitor.  However if you consider typical consumer set top boxes, VCRs, DVD players etc, which vastly outnumber broadcast gear, they usually have the composite video output stage running from a positive supply only and do require an output capacitor.

Inputs (broadcast and consumer) are universally AC coupled after the 75 Ohm termination which then means that the absolute voltage of black level varies with video content and black level clamps are incorporated where absolute levels are needed eg inputs to ADCs.

Displaying two fields on the scope will not enable the OP the discern if the signal is interlaced or not.  It requires examination of the vertical sync area to see the timing of the start of the broad pulse(s) relative to horizontal sync pulses.  Most likely the spectrum analyser is producing a non-interlaced signal and might be 60 Hz.  Observation of the OP's video clip shows that field sync is stable. The slanted verticals indicate that the horizontal rate of the signal into the display is slightly slower faster than the horizontal rate of the display.

[vk6zgo]

In standard PAL, SECAM & NTSC video wave forms, the blanking level should be at zero volts, with the syncs negative of that reference, & the actual video positive.
The devices you are feeding your video to may be "fussy" about this.

Composite video outputs are frequently AC coupled and I have never encountered any video equipment - broadcast or domestic - which required the input video to be at a fixed DC level.  It is not correct to write "the blanking level should be at zero volts".  It is correct to state syncs negative and video luminance positive.

They are not commonly ac coupled in Studio type Broadcast TV equipment in Australia.
My comment did say "the equipment may be fussy.

In any case, it is convention if displaying analog video on an Oscilloscope, to set the blanking level as the reference point from which the syncs are positive & video luminance positive.

I have "looked at more video waveforms that I have had good breakfasts", but they were mostly with waveform monitors or analog 'scopes, where the former had the voltage levels for blanking, sync tips & peak white emphasised, & the latter with just a normal graticule.
The advantage of analog Scopes is that you can adjust the position of blanking level to a convenient graticule marking.

If the OP's probe was set to x10 but the scope set to x1 then the displayed levels are OK.

Yes, but as I pointed out, the display is messy & hard to decipher when you don't have the actual DSO in front of you.
I could have said, "OK, I scrunched my eyes up & finally determined that the levels were right" but thought my suggestions might give the OP a better idea of how to display such signals.

I also suggested trying to display two fields, just in case the converters "are too clever for their own good" & are getting confused if the video is in fact sequential, not interlaced.

I too have spent years looking at analogue video waveforms and designing video equipment to broadcast specs.  I don't dispute that broadcast gear often has +ve and -ve power rails which permits the output stage to be biased such that it does not require an output capacitor.  However if you consider typical consumer set top boxes, VCRs, DVD players etc, which vastly outnumber broadcast gear, they usually have the composite video output stage running from a positive supply only and do require an output capacitor.

Inputs (broadcast and consumer) are universally AC coupled after the 75 Ohm termination which then means that the absolute voltage of black level varies with video content and black level clamps are incorporated where absolute levels are needed eg inputs to ADCs.

Displaying two fields on the scope will not enable the OP the discern if the signal is interlaced or not.  It requires examination of the vertical sync area to see the timing of the start of the broad pulse(s) relative to horizontal sync pulses.  Most likely the spectrum analyser is producing a non-interlaced signal and might be 60 Hz.  Observation of the OP's video clip shows that field sync is stable. The slanted verticals indicate that the horizontal rate of the signal into the display is slightly slower than the horizontal rate of the display.

If you look at the video signal prior to the onset of the field sync pulse, with one field, the last active line will be half the duration of the other lines, whereas with the other field it will appear as a complete line.

When I said "displaying two fields", I took it for granted that the OP would examine the field syncs.

As the OP's "7z" video clip asked for money for proprietary software, I declined the offer to spend on something I would look at once.
If the field sync is stable, whether it is 60Hz or not shouldn't matter.
For NTSC, line rate would normally be a bit faster than for PAL (or any 625/50 system).

The line syncs still are a bit strange, at around 6.7us duration, compared to around 5us in analog broadcast standards, although it seems unlikely to have any effect.
Maybe if the device uses keyed clamping, it may be trying to clamp part of the extended duration sync pulse to blanking level.

[Benta]

I think the main problem is that the OP does not have a screen/monitor/converter that'll work with the relatively slow scan rate of PAL/NTSC etc.
And who knows whether it's interlaced or progressive scan? Could also play a role.

[coromonadalix]

was there some  multi input signals to lcd / tft interface not costing a fortune who where able to cope with signals like this ??

[james_s]

That video circuit looks very much like that used in a lot of the old Atari B&W arcade games. The signal those produced was non-interlaced with NTSC-ish timings but it wasn't really NTSC. Many LCD monitors are not nearly as tolerate of goofy signals as analog CRT displays are. Make sure your display is truly capable of handling standard definition composite video.

[vk6zgo]

I think the main problem is that the OP does not have a screen/monitor/converter that'll work with the relatively slow scan rate of PAL/NTSC etc.
And who knows whether it's interlaced or progressive scan? Could also play a role.

That is why i suggested looking at two fields, to see if they are different.

One thing I did notice is the lack of colour burst.
It would be very unusual for that to matter, unless they used the burst as an important part of the converter timing.

The OP says the converters worked well with standard video signals from an old VHS player and a PS2, so it still seems to come back to something different about the video signal out of the R2365A.

[wasedadoc]

I used the free 7zip utility to open the 7z file and extract the mp4 file. The media player in Windows 10 played the mp4 file. No purchases needed.

[neuschs]

Hi guys,
thanks for the all the feedback. In the mean time I had the possibility to test another COmposite Video to VGA "Adapter/Converter" but I didn't hat look either. But I finally had the chance to test it on a native implementer of composite video. Even thouh the connection was janky as hell (you can see in the attached picture) it worked with out any issues.
This results in one question, where can I get a converter which accepts those signals, I haven't found any converters online which seem which are different to the the ones I've tried (just visually).
Regarding the units I tried - there are some pictures attached.

[vk6zgo]

I used the free 7zip utility to open the 7z file and extract the mp4 file. The media player in Windows 10 played the mp4 file. No purchases needed.

Thanks for that.

Encouraged by your comment, I found a free utility in the Windows Store, & did the same.
It really is not synching horizontally at all.

As I said before, the only thing that looks to be "out of whack" is that the horizontal syncs are quite a bit longer in duration than the broadcast standards.

It would be possible, working in the analog domain, to strip them off, use the leading edge to trigger a narrower pulse, then add that back into the composite waveform.

Having said all that, maybe it is simply a fault in the video generation in the R3265A, causing the timing relationship between horizontal & vertical syncs to be lost.
This will not show up on the 'scope if the OP just looks at a couple of lines but should be visible if a whole field is displayed, as the horizontal syncs will be seen moving through the display.

[Benta]

I still think it's the low line frequency that's the problem. VGA is 31 kHz, and that's what those converters expect.
I'd try the following: Take your "derivat_a" converter and connect its output to a VGA-to-HDMI converter. Alternatively to a VGA screen directly.

[wasedadoc]

I still think it's the low line frequency that's the problem. VGA is 31 kHz, and that's what those converters expect.
I'd try the following: Take your "derivat_a" converter and connect its output to a VGA-to-HDMI converter. Alternatively to a VGA screen directly.

No. Mention of VGA is a red herring:

1.  The scope trace is clear evidence of the line rate.  31 kHz does not correspond to 64 microseconds.

2.  The composite video output works OK with the TV.  SCART inputs on TVs do not accept VGA 31 kHz line rate.

3.  The manual for the GANA converter (https://www.amazon.com/GANA-Composite-Converter-Adapter-Supporting/dp/B01L8GG6PW)(http://ecx.images-amazon.com/images/I/61GEZLqEiUS.pdf) is easily found online and specifically says NTSC/PAL/SECAM. All those have line rates of approx 15.7 kHz.

The most likely explanation is that the analyser outputs a non-interlaced signal which is not strictly any of 525/60 or 625/50 standards but close enough for "analogue displays".  The AV2HDMI converter is expecting more rigid adherence to one of those.

[Benta]

Either I'm phrasing badly or you deliberately misreprensent what I said.
My point was, that there are practically no CVBS-to-HDMI converters on the market. On the other hand, plenty of VGA-to-HDMI, but connecting those directly to CVBS is bound to fail due to the low scan rate of CVBS.