midix
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Sun Jul 28, 2013 11:23 am

Heh, yes, this seller made me confused too, with his item price configuration :D . Weird, why did he pack multiple items under the same item ID...

I just measured the connectivity between the red wire and the pin 18 - seems good, almost zero (some 0.7 ohms from the multimeter wires themselves).
But still I'm not 100% sure - sometimes the electric components of a device also might have really low resistance, and it gets even more confusing if there are some capacitors in between - they tend to completely screw up resistance measurements.
To be sure that the resistance measured is actually for the wire itself and not for some electric components, I should cut the cable from the device, but I don't want to do that.

I'll now measure voltage on that wire with the device connected to my PC, and if it will be 5V then the next step - cut the wire and test how many mA does it consume. If it consumes a notiecable amount (50 or more mA), and is +5V and shows close to zero resistance when measured against HDMI pin 18, then it must be the power wire, right?
What is the chance that there might be some another HDMI wire which seems to act exactly as a power wire, but is not a power wire? :roll:

midix
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Sun Aug 04, 2013 5:41 pm

I'll share my results in case someone else gets the same make and model which I bought.
I measured power consumption, and this HDMI->VGA adapter consumes about 330mA. It means, it's not safe to attach it straight to Rasp.
I cut the red wire which I mentioned in my previous posts, once again verified that it is indeed connected to HDMI pin 18, and then I used an old USB cable from a broken mouse to pass +5V to the HDMI->VGA adapter. After that I verified that there are no short circuits. Actually, there were :oops: . I missed one tiny naked spot on the adapter, and my new +5 wire was short-circuited to the ground. I took additional care to insulate it.

Now everything seems working fine, picture is nice and clear, without any additional OPENELEC configuration. 8-)

TrevorG
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Sun Oct 20, 2013 10:28 pm

Pity I did not find this thread before I started to use one of these cheap HDMI ->VGA adaptors. I purchased a Camac one and had been using it for over 6 months with no trouble. Just over a week ago I lost the signal to my VGA monitor. Traced it to the power supply only putting out about 2V and the board getting very hot. Put the Pi on a more chunky supply with everything else unplugged current consumption 1.4A.

Tried the Pi again yesterday the current consumption had fallen back to 800mA but the Broadcom chip was still running at 70C. Tried attaching the HDMI ->VGA adaptor again but nothing came out (added 400mA to the current consumption). D1 is still a diode!

The Pi still appears to be fully operational except no video output. Fortunately as it is a Model B I can still login over Ethernet.

Put simply the HDMI ->VGA adaptor has left me with partially functional Pi. For the replacement Pi I will splash out on a more expensive monitor that does need the dreaded HDMI ->VGA adaptor :cry:

Trevor

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mahjongg
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Sun Oct 20, 2013 11:03 pm

you probably wouldn't have had any problem if only you you had used an adapter that wasn't powered by the PI, the PI simply isn't designed to power HDMI to VGA adapters, especially (but not exclusively) not through the HDMI cable.

cogwheel
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Mon Oct 21, 2013 6:18 pm

I'm new to this, so please excuse my limited knowledge. Does this adapter seem fit to avoid the problem?
http://dx.com/p/hdmi-male-to-vga-female ... red-229078

pwinwood
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Mon Oct 21, 2013 7:23 pm

cogwheel wrote:I'm new to this, so please excuse my limited knowledge. Does this adapter seem fit to avoid the problem?
http://dx.com/p/hdmi-male-to-vga-female ... red-229078
Yes, this looks like it should work assuming that the device requires the 5 volt power supply to be connected for the device to operate.

Charles_M
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Sat Oct 26, 2013 5:11 pm

I have one of those HDMI to VGA adaptors and had various problems trying to output 1280x1024 (mode 35) to an old AOC monitor. Sometimes it worked, sometimes a blank screen (actually 1184 x 624 but outside the monitors range). The voltage across the BAT54 was measuring >0.6v, board voltage 4.9V, leaving 4.3v to power it - something wrong there.

I took the adaptor apart and soldered 2 wires to the board to power it from a bench supply set to 5V, plugged it back in to the Pi and everything workd fine with a really good monitor image, consistently and at every boot up. The converter draws 200mA when outputting video, which is way too high and why the BAT54 is dropping 0.6V - it could drop even more according to the data sheet (max 0.8V at 100mA). I'm going to put the board in a small box with power connected to an old 5V psu. Obviously a powered convertor is the best solution.

managementboy
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Fri Dec 06, 2013 10:30 am

This week I purchased this HDMI-VGA converter. The pictures show that a red cable is connected to the 5v spot. Am I right? Has someone modded this cable/converter?

http://imgur.com/a/CEzOA

Image
Image

Phill Rymer
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Sun Dec 08, 2013 5:05 pm

would it be best or safer to use a powered converter box

andrewclark55
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Thu May 01, 2014 3:35 pm

I have been testing VGA adaptors for a charity supplying computers to schools in Africa that has purchased 50 RPi units but has VGA-only monitors for them all that were donated.

I tried the Kanaan adaptor first (available from Amazon) as it seems to have worked for some people.

I set it up on the bench with a power monitor to see how much current The Pi would draw without/with the adaptor. It drew an extra 1 Watt but seems to have blown the video output of the Pi straight away :(

Not totally unexpected, I admit, but no way to prove/disprove without trying.

1. Can anyone say what resistance one should expect across the diode? It shows high resistance in one direction and 150 ohms in the other, whilst still soldered in. That seems low for a diode, but I have no experience of this type.

2. I suspect VGA is not the way to go here, but the charity cannot afford new HDMI or DVI monitors. How practical would it be to use composite video output into a TV with RCA connectors? (My Pi no longer works so I can't try this!).

I have ordered a PMEG2010AET as suggested above to try and repair the Pi.

Grateful for any advice.

Regards
Andrew

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GTR2Fan
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Thu May 01, 2014 4:15 pm

HDMI-to-VGA converters with their own separate power source are generally recommended over ones that source their power from the HDMI port for this exact reason.
Pi2B Mini-PC/Media Centre: ARM=1GHz (+3), Core=500MHz, v3d=500MHz, h264=333MHz, RAM=DDR2-1200 (+6/+4/+4+schmoo). Sandisk Ultra HC-I 32GB microSD card on '50=100' OCed slot (42MB/s read) running Raspbian/KODI16, Seagate 3.5" 1.5TB HDD mass storage.

dem1980
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Wed May 28, 2014 12:08 pm

pwinwood wrote:
cogwheel wrote:I'm new to this, so please excuse my limited knowledge. Does this adapter seem fit to avoid the problem?
http://dx.com/p/hdmi-male-to-vga-female ... red-229078
Yes, this looks like it should work assuming that the device requires the 5 volt power supply to be connected for the device to operate.
This adapter seems to be cool because, we can use it without the 5V cable, like the same adapter which have only HDMI=>VGA with audio on the side.
This version could be an updated version.
It could be nice if the 5V could be taken from the pi's usb instead of the hdmi like some passive adpater.
Pi's usb could bring more power than the hdmi to power the conversion.
Some feedback on this new version "HDMI=>VGA with audio and power" ?

nars
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Wed Jul 08, 2015 4:28 am

Is this still same on Pi2? Same 200mA limit for HDMI?

Why no polyfuse to protect HDMI to avoid diode burning (and even worst problems if diode get's shorted...)?

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Burngate
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Wed Jul 08, 2015 9:09 am

Because a polyfuse wouldn't be fast enough.
On both the B+ and the 2B there is a chip - U9, AP2331W - between the raw 5v and the HDMI power pin. That limits the current to around 400mA and protects against short-circuits and reverse current.

nars
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Wed Jul 08, 2015 9:52 am

Thank you for your reply Burngate, that means that the burned diode problem described on this topic doesn't exist in the B+ and 2B at all? and we can safely use any HDMI powered VGA to HDMI adapter up to 400mA on B+ and 2B?

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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Wed Jul 08, 2015 11:15 am

nars wrote:Thank you for your reply Burngate, that means that the burned diode problem described on this topic doesn't exist in the B+ and 2B at all? and we can safely use any HDMI powered VGA to HDMI adapter up to 400mA on B+ and 2B?
Yes!

But note that if your adapter draws that much current, it WILL affect the power supply of the PI, that is:
Both the PSU, microUSB cable and the polyfuse will be extra loaded, so must be able to handle that.

nars
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Wed Jul 08, 2015 5:45 pm

I see. Thank you again for your clear and helpful explanation.

Dranoweb
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Fri Oct 30, 2015 8:19 am

I believe I've fallen victim to the same shortfall.
I have a sick B+ after plugging in one of these HDMI to VGA adaptors, and it indeed tried to pull a tremendous amount of current.

I've since found a HDMI monitor instead.
and I run many Pi's for various things o no great deal.

But it would be nice if someone could direct me to the location of the HDMI power diode on the B+ (formerly D1 on the A+).
I am very competent with a soldering iron, and think I may be able to replace it.

No love lost if I fail though, but I'm properly equipped for SMT stuff.
And apologies for reviving this old thread...

Fidelius
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Wed Dec 02, 2015 10:10 am

So, an active HDMI to VGA convertor (like this VicTsing one) should work for a Pi2, I suppose?
Still, Dranoweb had problems with his Pi1 B+. Isn't the video hardware part of the Pi1 B+ very similar to or the same as the Pi2 ?

And what would happen if I connected my Pi1 (model B rev2) to this VicTsing adapter?

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mahjongg
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Wed Dec 02, 2015 10:39 am

Read the comments on the site, there are several positive comments about using it with a PI.
Early PI's used a very small diode capable of only 50mA or so to feed 5V to the HDMI port, reasoning that for feeding the EEPROM in the monitor that would suffice, but people started using adapters that fed of this very minimal power source, and drew four or five times the maximum amount that the diode could deliver, so it burned out.
Since then the RPF has either used a much beefier diode, or another solution.
But note that using an adapter that uses extreme amounts of power will still decrease the "power budget" of the PI, which is decided by the PI's polyfuse (which for most PI's is 1.1Amperes, but 1.8A for the 2B).
In the mean time makers of such adapters noticed the problem with feeding from the HDMI port, and made their adapters more energy efficient, and also decided not to rob power from the EEPROM (looping though the power to the EEPROM) as blocking the power to the EEPROM (so its there to use for the adapter) has severe consequences for the user.
These days, with a modern PI, most adapters will work out of the box.

Fidelius
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Wed Dec 02, 2015 11:18 am

Thank your for your detailed answer, Mahjongg.
mahjongg wrote:Read the comments on the site, there are several positive comments about using it with a PI.
I filtered the user comments for "Raspberry", resulting in three matches all having a positive experience: two users say the adapter works with their Pi2, and one user says it works with his Pi1:
User wrote:I'm using the adapter to connect my Raspberry B to a legacy Viewsonic monitor (VP171s).
So with a bit of luck it could also work with my Pi1 (model B rev2).

On Amazon's German product page of this VicTsing adapter there's even 13 user comments from Pi owners all saying the adapters works well with their Pi – although they don't mention the "Pi B" in particular I think, but more often the Pi2.

Ein schöner Gruß in die Niederlande!

Fidelius
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Fri Dec 04, 2015 8:00 am

The mentioned VicTsing active converter works fine with the Pi1 (B) and Pi2. That's great.

In order to hear audio from the Pi's jack-socket while the VGA-converter is plugged-in the Pi's HDMI socket, hdmi_ignore_edid_audio=1 is useful. See config.txt help page.
Fidelius wrote:So with a bit of luck it could also work with my Pi1 (model B rev2).
Also the Pi1 B is happy when the config.txt contains config_hdmi_boost=5 , which is the standard value for the later models.

ulix
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Re: Serious HDMI Problems. What's that smell? Burning Raspbe

Mon Dec 07, 2015 8:53 pm

Hi,
this Thread could be very important now!
Does the Zero handle the power consumtion of the non powered vga adapter very well?

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