HDMI to VGA, should be simple... ?

[Justin Passing]

New laptop, no VGA-out so I used a simple converter, a few quid from ebay, fine.

Another projector won't have it. Someone else's worked, though the proj took 10 seconds to see it. I bought a new one, with a usb connector for power, but that didn't work either.

Anyone have an idea what might be the problem?

 

[Tigercubrider]

What resolution does the vga expect v the output of the converter?

 

[RandomGrinch]

What is the model of the projector?
If the projector only has a VGA connection, this suggests it is quite old and may only have a native resolution of 1024x768!
Try setting your laptop to this and see what happens.
The other way to reliably display to fussy projectors with fussy laptops, is to use external display only (turning off the laptop screen) - a bit of a pain if doing a presentation, but often works.
Use Windows key and 'P' to cycle through the display options.
Good luck!

 

[Justin Passing]

I tried it at 1024 x 768. Adapter is up to 1080P (1920 x xxxx)
From my olde laptoppe it worked at something higher than 1024 x 768, and the new one at whatever that is (1600x or 1920 x) , with the other person's adapter.

I read there's a handshake with HDMI. The laptop bimboms and as it recognises either adapter, but I forgot to ceck the "working properly" thing though.

I don't know wha the power connection is for, as most don't have it. Games consoles recommend an adapter which has it, though.

Good isea to try sole output, it might kick it into life.

 

[Lucid]

@Justin Passing , your info is a big vague on things such as makes and models but the image above does help.

HDMI out to VGA relies on active signal conversion. That means a simple wired cable such as the one in the image below won't work.

However, it looks like you've got something with active conversion where there's a circuit built in to convert digital to analogue. That explains why there's a power connector.

Regarding the power connection; HDMI includes a 5V power rail in the connection to power the receiver chip in whatever sink device an HDMI source is connected to. The idea was that even if say a display as a sink was not powered, then with the 5V rail power in the HDMI signal the source and display could do a handshake to work out a common set of display and audio parameters. More simply, the source asks the display what audio and video settings it supports.

It didn't take third party adapter manufactures long to work out that the power was there and to try to steal it to power their splitters, switchers and other devices. That's not what it was designed to do, and so the results can be flaky, hence the provision of a separate power socket.

HDMI also includes a content protection system called HDCP. This stops certain content such as Hollywood movies displaying on non-compliant displays. A VGA connection doesn't support HDCP, and so when the source HDMI chip tries to speak to a VGA display it gets no answer. That shouldn't be a problem with displaying a Windows desktop or a PowerPoint slide show, but HDMI can be a fussy beast. The standing joke when HDMI first hit the consumer display world was that the letters stood for Hardly Developed, Mostly Intermittent.

There are HDMI to VGA adapters which get around the HDCP issue by spoofing the source device in to thinking it has a valid HDMI-compatible display in the signal chain. I used to use these quite regularly to connect Blu-ray players and games consoles to high-resolution home cinema CRT projectors such as Barco Cine9s, 1209s, Ampros and Electrohomes.

The catch is that these adapters weren't "a few quid" off Ebay or Amazon. The best known was the HDFury range. The models evolved as HDMI standards changed, but for cost you were looking at £200-£300.

The price was kind of acceptable since it was a unique solution, and in the context of getting Blu-ray to work with a £20,000 CRT projector it wasn't going to dent the owner's wallet too badly. For owners of second-hand CRTs though where they'd spent maybe £3,000-£5,000 it was a bigger ask. After a while I managed to find a cheaper alternative for around a third of the price. The image quality was good enough with all but the highest-resolution CRTs.

Back to your issue, both @Tigercubrider and @RandomGrinch are on the right lines; get the laptop to output solely to the HDMI port and at the correct resolution to match the native display rate of the projector. As long as you're not trying to display HDCP-flagged content then that should work unless the lappies output is HDCP-locked. If it is then you're going to have to bite the bullet and buy an adapter like your friend's or one with the same kind of spoofing technology as the HDFury.

 

[Justin Passing]

Thanks, but
both types have a processor etc in the connector, looking as though they're similarly sophisticated. HDMI being digi and VGA analogue, of course they aren't just cable or they wouldn't work the things they do. Obviously they take power from the HDMI connection, pin 18 of the std one states 5V50mA. I've used the cheap one(s) on other projectors (apart from the latest new one) and they're fine. I don't know what make/model the difficult projector is.
Resolution, I'd already covered.
The £30 ones look the same as the £3 ones - quite likely the latter just use components which have benefited from mass production.

So the questions remain - what does the USB lead do, and how would I know if a different adaptor would be more likely to work?
What are the different specs which may apply, if any?

 

[Tigercubrider]

I have a load of hdmi to vga adaptors (cheapo ones from Amazon) to get some old plasmas that I got for free working with media players.
They all need usb power.
I doubt any hdmi power is capable of powering a converter.

you may find that some Amazon hdmi type amps/ splitters will pass through HDCP and remove it.
You need to read the reviews and even then it’s down to luck as Chinese stuff changes batch to batch.

you could just be unlucky in that you have two bits of gear and no common setting.
There are various boxes that can alter and transcode like a decimation but it’s getting expensive and cheaper to buy a new projector

 

[Lucid]

Thanks, but
both types have a processor etc in the connector, looking as though they're similarly sophisticated. HDMI being digi and VGA analogue, of course they aren't just cable or they wouldn't work the things they do. Obviously they take power from the HDMI connection, pin 18 of the std one states 5V50mA. I've used the cheap one(s) on other projectors (apart from the latest new one) and they're fine. I don't know what make/model the difficult projector is.
Resolution, I'd already covered.
The £30 ones look the same as the £3 ones - quite likely the latter just use components which have benefited from mass production.

Hang on a sec. You come on here with a barely-literate explanation of your problem. You haven't answered questions regarding makes and models of gear even when asked. It's not clear what you do know and what you don't know from your posts, and I may remind you that we are not mind readers. If you have some relevant information then flippin' well write it in the posts. Then, when someone takes the time to explain the background as to why stuff might not work because of less-than-obvious reasons for a newbie, you have the gall to throw it back in their face.

It sounds a lot like you're just chucking things together in the hope that somehow it'll work.

The cheaper units could be that they're supplied direct, or that they're more basic and with no guarantee they'll work. The more expensive ones could just be inflated prices, or they could be the ones where some care has been taken to ensure they'll do the job. Maybe a mix in between.

So the questions remain - what does the USB lead do, and how would I know if a different adaptor would be more likely to work?

Read the text from the picture you posted

Power supply interface

Power. Supply. Interface.

Power

Supply

Interface


Getting the message yet?



I'm done with you. Sort out your own problems.

 

[Justin Passing]

Hang on a sec. You come on here with a barely-literate explanation of your problem. You haven't answered questions regarding makes and models of gear even when asked. It's not clear what you do know and what you don't know from your posts, and I may remind you that we are not mind readers. If you have some relevant information then flippin' well write it in the posts. Then, when someone takes the time to explain the background as to why stuff might not work because of less-than-obvious reasons for a newbie, you have the gall to throw it back in their face.

It sounds a lot like you're just chucking things together in the hope that somehow it'll work.

The cheaper units could be that they're supplied direct, or that they're more basic and with no guarantee they'll work. The more expensive ones could just be inflated prices, or they could be the ones where some care has been taken to ensure they'll do the job. Maybe a mix in between.



Read the text from the picture you posted

View attachment 261454

Power supply interface

Power. Supply. Interface.

Power

Supply

Interface


Getting the message yet?



I'm done with you. Sort out your own problems.

I don't need to read anything, you do.
You evidently didn't read in my first post "with a usb connector for power".
Everyone has the message except you.
You've posted in capitals, with umbrage, the same as I put in the first post, and appear to want credit for it. Sad.

You said an adapter is needed not a cable. I wrote that it was a converter and the same device had worked with a different projector. Which a cable wouldn't have done. All the ones with usb for power aren't just cables, surely you can work that out. No point raising that, then, is there. No.

"It sounds a lot like you're just chucking things together in the hope that somehow it'll work."
Well if you have any knowledge or suggestion which might be useful but won't pass it on, then all forums will be "done with" you - nobody wants all noise and volume with no information signal.

It seems not, so it's better not to post because it makes you look just a bit desperate.

 

[Justin Passing]

I have a load of hdmi to vga adaptors (cheapo ones from Amazon) to get some old plasmas that I got for free working with media players.
They all need usb power.
I doubt any hdmi power is capable of powering a converter.

you may find that some Amazon hdmi type amps/ splitters will pass through HDCP and remove it.
You need to read the reviews and even then it’s down to luck as Chinese stuff changes batch to batch.

you could just be unlucky in that you have two bits of gear and no common setting.
There are various boxes that can alter and transcode like a decimation but it’s getting expensive and cheaper to buy a new projector

Ah, Helpful info! Thank you.

I don't need HDCP and that, this is Powerpointy stuff.
Hmm, there's a dearth of info in the product descriptions, apart from lots of, "it never worked so it's cr@p innit".

The power specced for the standard hdmi connection is 5V at 50mA, versus VGA with a few analogue lines at 0-0.7V into a 1kΩ, ie a few mA , so there could be enough power if the line's not long. Dunno. I gather games achines need the USB - wouldn't surprise me if they don't comply with standards too rigorously

I've read of time delays (one of these takes several seconds before things work) and handshakes of which I know nowt.
"Transcode like a decimation" which aren't terms I've heard so thanks I'll look them up. I might find a magic term lurking in an ad. Even a "highest price first" search doesn't illuminate so far, though.

Tiger cub... one up from a Bantam, wonnit? Never had the pleasure

 

[RandomGrinch]

At one point a few years back, nearly every laptop had an HDMI port, but our lecture theatres only had RGB connectors to the projectors.
I bought a load of adapters from CPC (ProSignal and StarTech):
https://www.easyflip.co.uk/CPC_Catalogue/?page=485

They just worked - they may be exactly the same inside, as a cheap one from Amazon; but being a named brand, from an approved supplier - they have to work!

The power specced for the standard hdmi connection is 5V at 50mA, versus VGA with a few analogue lines at 0-0.7V into a 1kΩ, ie a few mA , so there could be enough power if the line's not long. Dunno. I gather games achines need the USB

The 50mA supply isn't just about the length of RGB cable, but also about powering the 10bit DAC/microprocessor (Probably only another couple of mA, but it all adds up! ).
Although, I didn't need external power with any of the adapters I bought.

I tried it at 1024 x 768. Adapter is up to 1080P (1920 x xxxx)
From my olde laptoppe it worked at something higher than 1024 x 768, and the new one at whatever that is (1600x or 1920 x) , with the other person's adapter.

The adapter may be capable of displaying a huge range of resolutions, but the best quality image will always be displayed at the projectors native resolution - this is well worth finding out!

...and you may not have found @Lucid 's post helpful and you may think it didn't answer your question.
However, the power of his explanation is to provide information not just to you, but for anyone who comes across this thread who has a similar issue.
And IMHO, that is something to value!

 

[Tigercubrider]

Decimator. Auto correct got in the way.
Not saying it will work but you may need some scaling to sort it out
However it may get expensive

http://decimator.com/Products/MiniConverters/MiniConverters.html

 

[Justin Passing]

At one point a few years back, nearly every laptop had an HDMI port, but our lecture theatres only had RGB connectors to the projectors.
I bought a load of adapters from CPC (ProSignal and StarTech):
https://www.easyflip.co.uk/CPC_Catalogue/?page=485

They just worked - they may be exactly the same inside, as a cheap one from Amazon; but being a named brand, from an approved supplier - they have to work!

The 50mA supply isn't just about the length of RGB cable, but also about powering the 10bit DAC/microprocessor (Probably only another couple of mA, but it all adds up! ).
Although, I didn't need external power with any of the adapters I bought.

The adapter may be capable of displaying a huge range of resolutions, but the best quality image will always be displayed at the projectors native resolution - this is well worth finding out!

...and you may not have found @Lucid 's post helpful and you may think it didn't answer your question.
However, the power of his explanation is to provide information not just to you, but for anyone who comes across this thread who has a similar issue.
And IMHO, that is something to value!

Thanks I'll look at those brands. That's the sort of info which helps.
I appreciate electronics needs power, bit it appears there's > an order of magnitude more than it requires for the signal, available. 250mW, versus 0.49mW per wire.
More power would also be needed to create faster signals against the impedance of the cable for higher resolutions as well as faster clock rates in ADCs. The claims versus usb cable use, don't correlate well with that, though. And nothing much carries certification.
I can't tell what model the old projector is without reference to management services dept, and given the dearth of info about converters, there's not much I could do with information about it. The VGA cable is unknown, too. Hence trying the lower resolutions, as I said, to 1024 x 768 at the laptop end..

The post you refer to dumping obvious, known, and irrelevant stuff, especially about old systems, in here, isn't likely to be useful to anyone on this topic, I think. The gold devices he shows are VGA to HDMI, not even the relevant way round! There are more appropriate places to get those descriptions. Peripheral info is ok to a point but not if it's instead of anything useful. It looks like the poster just wants to 'big himself up' regardless of what was asked. The belligerent attitude about "getting the message" on what was already posted, and his tag line demanding his "thanks" count is boosted, which he has pressed in the past, shows him up.
I could post about attenuation in long transmission lines, EQ, eye patterns, characteristic impedances blah blah which might educate someone and it's tangentially relevant, but I'd have to be a tw@t to do it because it's not appropriate. It doesn't help with the solution.

It seems the answer is mostly - Trial and Error, stop when you find one which works!

 

[opps]

It seems not, so it's better not to post because it makes you look just a bit desperate.

I don't have a "dog" in this "fight". I will however admit that whenever I have posted on this sub forum, Lucid is the person that I (ultimately, but not exclusively) want to respond to my question.

For the record, I have never found him to be anything other than helpful. I, respectfully, suggest that something might have got "lost in translation".

It doesn't reflect well upon the site when people are critical of each other. This site relies upon tradesmen that devote their time to trying to help others.

 

[oldbutnotdead]

Have another very careful read on the spec on your converter. I bought a pair of cheap HDMI baluns to get main TV repeated upstairs. They worked sometimes....I investigated and they are designed to work at a fixed resolution no greater (obviously) but also no less. Can't remember the numbers, think the res was 1080i- so set Virgin box to that, tune to BBC or itv, all good. Tune to a high number channel showing lower-res content the box would derate to the lower Res and the link would stop working.