Advantest R3265A Composite Video Out - Page 1
Forum section: electronics / projects

author: neuschs
author_rank: Contributor
timestamp: May 15, 2023, 08:14:27 pm
content: 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.

author: wasedadoc
author_rank: Super Contributor
timestamp: May 15, 2023, 09:12:44 pm
content: 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?

author: neuschs
author_rank: Contributor
timestamp: May 15, 2023, 09:40:21 pm
content: 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).

author: wasedadoc
author_rank: Super Contributor
timestamp: May 15, 2023, 09:49:07 pm
content: Quote from: neuschs on May 15, 2023, 09:40:21 pmIn 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.

author: Benta
author_rank: Super Contributor
timestamp: May 15, 2023, 10:18:05 pm
content: 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.

author: neuschs
author_rank: Contributor
timestamp: May 15, 2023, 10:22:50 pm
content: 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.

author: wasedadoc
author_rank: Super Contributor
timestamp: May 15, 2023, 10:35:56 pm
content: Quote from: neuschs on May 15, 2023, 10:22:50 pmNo 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.

author: Benta
author_rank: Super Contributor
timestamp: May 15, 2023, 10:51:15 pm
content: 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.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 16, 2023, 01:46:23 am
content: Quote from: Benta on May 15, 2023, 10:18:05 pmThe horizontal syncs are bit excessive in duration, but that shouldn't matter much.I reallyhatethe '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".

author: neuschs
author_rank: Contributor
timestamp: May 16, 2023, 08:15:54 am
content: 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.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 16, 2023, 09:03:44 am
content: Quote from: neuschs on May 16, 2023, 08:15:54 amIf 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.

author: wasedadoc
author_rank: Super Contributor
timestamp: May 16, 2023, 12:20:44 pm
content: Quote from: vk6zgo on May 16, 2023, 09:03:44 amComposite 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.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 16, 2023, 01:27:59 pm
content: Quote from: wasedadoc on May 16, 2023, 12:20:44 pmThey are not commonly ac coupled in Studio type Broadcast TV equipment in Australia.My comment did say "the equipmentmaybe 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.QuoteYes, 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.

author: wasedadoc
author_rank: Super Contributor
timestamp: May 16, 2023, 02:11:59 pm
content: Quote from: vk6zgo on May 16, 2023, 01:27:59 pmI 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 slightlyslowerfaster than the horizontal rate of the display.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 16, 2023, 11:51:32 pm
content: Quote from: wasedadoc on May 16, 2023, 02:11:59 pmIf 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 bitfasterthan for PAL (or any 625/50 system).The line syncs stillarea 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.

author: Benta
author_rank: Super Contributor
timestamp: May 17, 2023, 12:08:34 am
content: 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.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 17, 2023, 12:49:57 am
content: was there some multi input signals to lcd / tft interface not costing a fortune who where able to cope with signals like this ??

author: james_s
author_rank: Super Contributor
timestamp: May 17, 2023, 02:37:46 am
content: 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.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 17, 2023, 03:51:40 am
content: Quote from: Benta on May 17, 2023, 12:08:34 amThat 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.

author: wasedadoc
author_rank: Super Contributor
timestamp: May 17, 2023, 07:29:27 am
content: 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.

author: neuschs
author_rank: Contributor
timestamp: May 17, 2023, 04:25:51 pm
content: 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.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 18, 2023, 12:05:16 am
content: Quote from: wasedadoc on May 17, 2023, 07:29:27 amThanks 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.

author: Benta
author_rank: Super Contributor
timestamp: May 18, 2023, 11:24:15 am
content: 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.

author: wasedadoc
author_rank: Super Contributor
timestamp: May 18, 2023, 01:10:29 pm
content: Quote from: Benta on May 18, 2023, 11:24:15 amNo. 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.

author: Benta
author_rank: Super Contributor
timestamp: May 18, 2023, 06:29:35 pm
content: 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.

author: james_s
author_rank: Super Contributor
timestamp: May 18, 2023, 06:37:31 pm
content: Quote from: wasedadoc on May 18, 2023, 01:10:29 pmThis is almost certainly the case. These converters are way more fussy than an analog CRT. NTSC is interlaced with quite precise timings, it is very common for computers and video games and such to produce a non-interlaced signal that is close enough to NTSC timings for a CRT to work fine, but it won't work with something that is expecting interlaced NTSC video.I have used one of those cheap little backup camera LCD monitors for testing early arcade boards and FPGA implementations of them so some LCD monitors do handle these odd signals just fine.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 19, 2023, 12:50:44 am
content: Quote from: Benta on May 18, 2023, 06:29:35 pmI am an old-style Broadcast standard TV person, so I normally think PAL/NTSC Composite video.Googling verifies my vague ideas about VGA as basically an RGB system with separate Horizontal & vertical sync connections, normally implemented using a 15 pin D-sub connector, or sometimes with four BNC connectors. (Some of the incidental functions normally available with the 15 pin connectors are not available in the latter case.)If a converter is fitted with a single BNC/RCA video input & a HDMI output socket, it is fairly certain to be Composite video to HDMI.Googling, I found just as many CVBS to HDMI adaptors offered as VGA to HDMI ones.The market for the former is quite likely to be larger than the latter, as more people have legacy video sources than those who want to use an older computer with a modern monitor.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 19, 2023, 01:14:11 am
content: Quote from: james_s on May 18, 2023, 06:37:31 pmYes, analog monitors/TVs normally run the horizontal & vertical oscillators constantly, whether there are syncs available or not.Their free running rate is close to the nominal locked frequencies, & when they receive syncs, being basically PLLs, will lock to them.Except for very early systems like the old UK 405 line system, the line frequency of analog TV standards are very close & will lock without difficulty.Field rates may require a "tweak" of the vertical hold preset pot, although the last generation of TVs could recognise the 50Hz & 60 Hz systems & self-adjust.If a converter requires very precise timing, it might well become "confused".I am still suspicious that the Field & Line sync signals in the R3265A may not be locked.This can be easily checked by displaying the video waveform at field rate.If the H syncs are not locked to the V ones, they will drift through the display, just as they do on the monitor.

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 19, 2025, 03:09:38 pm
content: I also meet this problem. I managed to get the video out from r3265aThe next step is to make a board captureing the video data and display it on a 7inch tft display[ Specified attachment is not available ]

author: neuschs
author_rank: Contributor
timestamp: February 19, 2025, 03:41:22 pm
content: Can you explain how you managed to do so ?

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 19, 2025, 03:54:33 pm
content: Actually the protocal of the data from the "comp video" connector on rear panel is not any of the standard comp video protocal. I captured one of the frame from the crt connector (u can get the pindefine of this connector by looking at the maintenance menu, although the picture of the maintenance menu is different from my board) and analysed it for a while. Finnaly found that the number of the hsync in one frame is 257 it means the Vertical resolution is 257. And the data from the rear panel is the mixture of the crt video signal, So we can easily infer that the vertical resolution of the comp video data is also 257(while NTSC is 480).after figured out this, I just want to say: Holy danggg Advantest

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 19, 2025, 04:10:31 pm
content: pleaz read the last comment I've posted. It's a little bit longggg but that contains the key of doing that

author: neuschs
author_rank: Contributor
timestamp: February 19, 2025, 04:17:36 pm
content: After short googling I found nothing, but does anyone now some retro console that uses a similar resolution ? I mean that would at least allow to use maybe some retro hdmi/VGA Adapter board.Otherwise that would mean to use DIY converter.

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 19, 2025, 04:18:59 pm
content: Finally I'd like to share some chaos scene when I capturing the crt data by using the oscilloscope

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 19, 2025, 04:27:40 pm
content: I am using Verilog to complete the acquisition and analysis of the video stream, part of the simulation has been completed, and AD9057 will be used as adc in the hardware part, and also I'll use my Astrometer core first time in a project , but it may need to wait a few days, because I have a heavy academic workload these days 🥲

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 19, 2025, 04:44:55 pm
content: I'm afraid you won't be able to find this interface on the market. Its refresh rate is also quite unique, set at 60FPS. The reason for using this specific resolution is really simple: it needs a 60FPS refresh rate, whereas NTSC only supports a 30FPS refresh rate.

author: neuschs
author_rank: Contributor
timestamp: February 19, 2025, 05:36:24 pm
content: Weird enough that it actually works on a random TV as seen in a previous post of me.

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 20, 2025, 02:41:38 am
content: Quote from: neuschs on February 19, 2025, 05:36:24 pmI think the reason y it works is really simple. This signal is still standard comp video format, if the decoder is just work as the theory as the crt (decode the vsync and hsync directly, when get vsync return to the first pixel, go to the next row when get hsync), so it will get vsync signal then new frame start. Why the others didn't work is also really simple, they may use a digital buffer,so they return to the first pixel unless the buffer is fully filled. This is just my guess and I hope you can help you understand it

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 20, 2025, 02:46:06 am
content: I also find a screen fit the size of the window really well!!!What a nice day

author: zrq
author_rank: Frequent Contributor
timestamp: February 21, 2025, 11:46:12 am
content: If the problem is the weird 257 lines vertical resolution, is it possible to use some off-the-shelf converter boards like the "GBS-8220" to convert the resolution to something acceptable for VGA?

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 21, 2025, 02:13:07 pm
content: Quote from: zrq on February 21, 2025, 11:46:12 amI'm not too sure what that GBS-8220 thing is, but Im sure I'll have an HDMI output on my adapter board. If you can wait til I'm done, I'll probably open-source this project or sell the kit online.

author: JoeyDeng
author_rank: Regular Contributor
timestamp: February 22, 2025, 10:39:06 am
content: I finished the design of the adapter board

author: JoeyDeng
author_rank: Regular Contributor
timestamp: March 22, 2025, 12:41:18 pm
content: I successfully made a screen that matches this instrument perfectly, but now there's a new problem—I'm getting a "Calibration error of INPUT ATT" on my device.

author: picburner
author_rank: Frequent Contributor
timestamp: March 23, 2025, 06:39:59 am
content: For this SA (R3271A/R3265A) a color conversion had already been done usingstandard components and a dedicated PCB.But a solution using an FPGA is probably even better.