New motherboard improves old CRT television | Hacker News Reader

New motherboard improves old CRT television

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188 pointsrbanffy67 comments

The fact that it's for a CRT is the surprising part, but "universal" replacement boards for LCD TVs have been available for a while too. Here's a rare review of one, on a site that has sadly disappeared within only a few years:

http://web.archive.org/web/20190511065920/http://redlightgre...

Thanks for sharing that link - it’s quite a thorough write up! I wish there were things of like quality for CarPlay retrofits.

I wish there were things of like quality for CarPlay retrofits.

Porsche Classic is all I can think of ( https://www.caranddriver.com/news/a42571042/porsche-touchscr... ). Hopefully other manufacturers will get on board with that idea at some point.

Oh there are a ton of interposer boards you can buy shipped direct from China that add CarPlay to an existing oem head unit the same way you can get reverse camera support (high jacking the video output when a certain but is pressed or the gear shift changes). It’s just that they all have massive quirks. I’ve seen the Porsche Classic CarPlay retrofit and it’s absolutely the best, but these third party solutions are available for most makes and models but all have to a of quirks and idiosyncrasies that are never presented up front.

Wow. Who knew such things existed? Fantastic. I'd hate to resolder that data cable from the LCD though.

That board was cheap as hell, had every input and decodes MP4 video. WTF.

I guess that one reviewer either didn't bother to order one with the right connector, or received it with the wrong one, but the pinouts are usually very standardised so there's no need to resolder the LVDS cable.

There's lots of videos on YouTube about these boards; unfortunately the vast majority seem to be in Indian or some other Asian country's language (despite English titles and descriptions). Here's one of the few English ones I could find: https://www.youtube.com/watch?v=C2YTL25iyHU

Another (unvoiced, English text descriptions) : https://www.youtube.com/watch?v=kM8_kJENdoQ

China is paradoxically filled with brilliant engineers making genius products, and mediocre engineers making products whose listings appear to be genius.

I fucking love gambling on AliExpress.

That's a great observation. I've bought stuff there that I could not even believe was as cheap as it was, I thought the price must be a typo and for sure it'll be adjusted. For electronics the pricing tends to be lower than the BOM at maximum volume discount when sourced from a large Western supplier.

And the vast majority of it just works, though I've had one or two duds.

But you need to be sharp when it comes to things that plug into a wall socket, open them up to inspect that they are safe.

I think electronics are just super cheap to make and they're overpriced when sold abroad.

Electronics are crazy. Depending on the amount of skill and/or effort you have available, there is an enormous spread of possible implementations at different price points.

For instance, I develop a product that we sell for $2500. When the company brought me in, the raw cost of the electronics was about $250. Right now I've got it down to $50, and I expect it to fall to $20 or $30 once we start producing at scale.

You’d want to hope your margins are that good distributing and marketing physical products. Gets expensive particularly if you’re retailing it and the retailer chain wants your margins for the honor of distributing with them!

I think we can describe that as just being filled with lots of engineers

Fair.

I bought one to repurpose an old laptop screen, if the screen uses a releasable connector, you can probably find a board that connects to it

Looks like machine translation from Russian original: https://mysku.club/blog/aliexpress/67872.html

Thanks for finding the original, and I did suspect it was translated from Russian due to the odd phrasing, but if it weren't for that site translating a copy and Google subsequently finding it, such interesting things might've never gotten discovered. As I mentioned in the other comment here, there's lots of videos on YouTube about these boards too, but barely any in English.

Here are some more links on those controllers and various LCD data:

https://www.mattmillman.com/info/lcd/rovatools/#comment-8933...

https://sites.google.com/site/lcd4hobby/home

https://github.com/ghent360/RTD-2660-Programmer/

http://openrtd2662.ru/

https://www.codeforge.com/article/258602

https://hackaday.io/project/179868-all-about-laptop-display-...

https://www.panelook.com/index.php

https://lcdtech.info/en/

https://repairalltv.com/main-board-universal-ds-d3663lua-a8-...

Thank you. You're downvoted, but I always really appreciate link dumps like these as a kick-off point for my own research.

Edit: here's one of my own! https://news.ycombinator.com/item?id=33359963

This video and reading the recent article referencing Brimar valves (of the vacuum tube variety) [1] led me down the rabbit hole of, how hard can it be to make a few CRTs. Despite growing up with them, it turns out I had no idea. Lots of ovens and nasty chemicals involved - see for yourself in this great old video [2]. I wonder if anyone in the retro scene is eccentric and rich enough to give it a go…

[1] https://brimaruk.com/

[2] https://youtu.be/32yYfTVIzBE

> https://youtu.be/32yYfTVIzBE

Great video. I’ve got to 6:06 so far no mention of nasty chemicals yet.

Transcript: https://youtubetranscript.com/?v=32yYfTVIzBE

From the transcript (I dislike watching videos), it appears the video never discusses the chemicals involved - but I’m sure some of them are rather toxic. It is an old film, and when it was produced people didn’t see the toxicity of chemicals used in manufacturing processes as being as worthy as note as people do today - both environmental and workplace health/safety issues were less on people’s radar. Plus it obviously is marketing/PR for the manufacturer, and who wants to mention toxic chemicals in something like that?

It's worth mentioning though that in general as our technology has gotten more exotic, so too the chemicals needed to manufacture it have gotten more toxic.

Is there some underlying rule/"law" of fabricated products shrinking in scale requiring increasing energy density/control for their manufacture (more reactive chemistries) presumably to counter a general backdrop of entropy / entropy-density?

10:37 has hydrochloric acid

Sounds like hydrofluoric acid to me, which is even more dangerous. But seeing as you're making a vacuum chamber anyway, perhaps oxygen plasma could be substituted.

https://en.wikipedia.org/wiki/Plasma_cleaning

I remember hearing the main issue is that the glass is made up of a significant amount of led so even if it was commercially feasible it would be legally impossible to sell, import or manufacture new CRT tubes due to the regulations many developed nations have in place.

How are car batteries sold, imported, or manufactured?

That was the explanation I was given when asked.

I imagine different regulations apply to different products. Also obviously different countries have different regulations.

Lead makes up 20-25% of the contents of the glass of a CRT tube so I imagine that restrictions like those listed in the link below would cause issues.

https://dtsc.ca.gov/restrictions-on-the-use-of-certain-hazar...

There are exemption. And if you think of it, it is a lot easier to properly dispose and recycle the plates in a car battery than in electronics solder or glass.

I can't speak for any other regulations, but the EU's RoHS has a specific exemption for lead in the glass of cathode ray tubes.

CRTs are still being actively manufactured, primarily for avionics and military applications.

https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A...

https://www.thomaselectronics.com/manufacturers/

https://moores-glass.co.uk/products/cathode-ray-tubes/

Fantastic, thank-you. Every day continues to be a school day!

Lead glass is only used for the back and sides of the tube. It can't be used for the faceplate because x-rays make it turn brown. Instead, barium-strontium glass is used for the faceplate. It seems that use of lead is only a cost optimization, and the whole thing could use barium-strontium glass instead.

Searching for "lead glass CRT browning" on Google found this sample chapter from an unidentified book, provided by the The Society of Photo-Optical Instrumentation Engineers, which includes some details:

https://spie.org/samples/TT54.pdf

The chapter is from:

Kenneth Compton, "Image Performance in CRT Displays", SPIE Tutorial Texts in Optical Engineering Vol. TT54

It's kinda mad we used to stare at an X-Ray gun though :) especially the ones in the 80s didn't quite filter all of them out.

It may just be me, but this video actually seems detailed enough to replicate the process if you have the right materials/machinery.

It's worth noting that there have been community efforts to develop an open source design CRT chassis:

https://vimeo.com/591387422

https://github.com/tdaede/td-crt

oh, that's great. Anyone selling kits of this? Or an Aliexpress version less geared towards TV and more towards gaming monitors, with VGA, composite and other useful input for retro computers?

Not that I know of.

RGB hacking is a thing though so for 15khz (~240 x 60hz) aka 240p it is often just simpler to tap into the OSD display chip (lookup jungle chip mod) input an RGB signal.

https://www.youtube.com/watch?v=VKhEpyFfAHs <- basic RGB mod.

https://www.youtube.com/watch?v=ANSxASanZes <- advanced RGB mod.

Been there, it works, but if the original crt board has issues (and you’re not good at diagnosing them) it would be great to get a good quality replacement

Good point.

What I would like to see is a board made for larger 100/120hz TVs. They often get no love from gamers due to the lag/processing of 240p content so they get junked. It would be a good solution to the lack of multimode CRTs. They are so rare/expensive.

The built-in game is Sokoban[1]. I know it from Nethack, but the one in the TV is just like the original.

[1]: https://en.wikipedia.org/wiki/Sokoban

Have lots care when opening a CRT TV. In fact, don't do it unless you know what you are doing.

I remember fixing up a CRT on an arcade machine I had in my office at work at one point. I read up on how to discharge it and made a makeshift tool to do the job (i.e. an insulated screwdriver with a wire attached to ground). I was pretty scared and even made sure to do it during work hours when others would be around in case I got zapped unconscious. :) Once I got was able to do it a couple of times, it really was no big deal, but I did take care not to get too close to the back of it while the thing was on and exposed.

Worse, it’s never been made clear to me which parts are the dangerous one. Just a lot of vague hand waving. Which I guess is fine if you don’t want liability?

If you're not sure about it, best to stay away. With a cursory web search or YouTube search, you can find plenty of information.

That’s probably because most people posting this useful advice don’t know themselves.

If unsure or nervous around electricity, just ground the segment you are working on first.

But the parts that should make you extra cautious have wires with a lot of insulation so they look thick. those are the 20Kv bits. you also will want to take the time to drain any big capacitors. you can just short the leads or if you are feeling conscientious(and don't like sparks) drain them with a resister(100kohms or so) between the leads.

The cathode ray tube is a giant capacitor. During operation it is charged to 20+ kilovolts, and it takes a long time to discharge even after being unplugged from the wall. (Some but by no means all TVs have a circuit which discharges the tube). There are also large capacitors in the power supply which maintain hundreds of volts even after being unplugged. When the TV is connected to power, the flyback transformer (a large circular device soldered to the main board) generates a range of voltages from hundreds up to 20+ kV which are wired to various parts of the tube. Some of these are present on the neck board which is exposed at the pointy end of the tube.

US TVs are extra spicy because they sometimes have no earth, so if the power is wired backwards (either in the plug or more insidiously from the wall), everything metal inside the set can be live.

If you overvolt the tube (a worry with this replacement board actually) then it can emit x-rays. Most "modern" CRT main boards have a circuit which detects this, but maybe older ones or cheap knock-offs don't.

In short, if you don't know what you're doing, stay away.

Ok. I can identify all of those parts and once did a cap replacement on a pac-man monitor. But that's enough to keep me from making it a regular thing.

A few sets I've had need to be on and open to make adjustments. I'm never a fan of that.

This is a case where having the right tool is actually a good idea. It'll have plenty of insulation and usually a VU meter showing the voltage (so you can see if it was charged and watch it drain). A screwdriver doesn't really have enough separation between you and the 20+ kV :-/

In what cases of repair is having the right tools not a good idea?

Its not a matter of not having the right tool is not a good idea, but sometimes, because of cost and or circumstances, you have to improvise and/or make due with what you have.

If you wear rubber gloves and keep your other hand in the your pocket, I dont see any actual problems.

Also long sleeves are good, I was recently zapped at the wrist when fixing an oscilloscope.

I think maybe the 20 kV abates rather quickly on its own, because I dont remember using much any caution when unplugging the anode plug.

Has to be serious rubber gloves to withstand 20kV :) the simple doctor's ones won't do

Surgical latex gloves are not what I picture when someone says "rubber gloves" but something more substantial typically used when cleaning in a shape that borders on a rubber gauntlet.

I know but not everyone who reads this would be as experienced to know this :)

Some people would still think "it's rubber so it doesn't conduct electricity so I'm fine messing with this TV".

But yeah CRTs are now so rare that I agree that it's very very unlikely for someone without much knowledge to tinker with them. You have to be really an enthusiast to even still own one let alone try to repair one instead of picking up a nice cheap flatpanel.

Personally I'd forgo the gloves (real protective ones are so clumsy it's hard to really do something productive with them) and make sure the caps are fully discharged. Though generally I'd steer clear from this stuff as I know I don't understand it well enough. I came up in electronics during the final years of CRTs so as my knowledge grew they became deprecated and I never really got the full grasp of them.

When I took a TV servicing class in high school in the 1970s we were told just to keep our left hands in our back pockets so the discharge will ground through our right side and not across our hearts. The biggest hazard was breaking our hand on the chassis as we jerked back from the shock.

I never heard of any kids getting hurt, so it was fine.

The risk of death or serious injury messing with CRT displays is grossly overstated (note the lack of data on related fatalities). Use common sense and you'll be fine.

Oh yeah, Adrians Digital Basement..Highly recommended youtube channel.

Mike's Amateur Arcade Monitor Repair on YouTube reviewed a similar 25" Universal Arcade Monitor Chassis a couple years back and was "blown away" by it. Definitely worth the money. High praise from a guy that knows CRTs inside out.

https://www.youtube.com/watch?v=i3u9sWDeoYE

2 pictures and a video somehow left me wanting for "before" and "after" pic showing how the television was improved

It's not that improved in picture quality, it's mainly improved in features - like the ability to display NTSC X PAL signals

This article is blog spam - you probably want to watch Adrian's video directly: https://www.youtube.com/watch?v=MoqflFfvkR0

Not entirely related but I didn't find much information about the NTSC/PAL decoding schemes. Lots of introductory material but nothing about what they actually did in televisions back then (especially the filtering side). I guess it's because of patents...

It's covered in detail in Wikipedia.[1]

Here's the NTSC color standard in the Federal Register.[2]

The data sheet for a modern NTSC/PAL decoder IC.[3]

Details of early color TV receivers.[4]

[1] https://en.wikipedia.org/wiki/NTSC

[2] https://www.govinfo.gov/content/pkg/CFR-2018-title47-vol4/pd...

[3] https://www.analog.com/media/en/technical-documentation/data...

[4] http://earlytelevision.org/color.html#systems

I was thinking about 2D filtering. But your comment triggered a new DuckDuckGo search and it happened to have some bits of information :-)

https://www.extron.com/article/ntscdb4

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