Cheap VGA->HDMI adapter

MasterOfGizmo · Post by **MasterOfGizmo** » Sun May 10, 2015 12:03 pm

Hi. That's bad news as this means that your adapter tries to source power from the vga connector. It seems the pin it uses for that is connected to gnd on the mist. This will shorten any usb power supply.

That means the adapter you have is not identical to mine ... i'll think of a solution.

MasterOfGizmo · Post by **MasterOfGizmo** » Sun May 10, 2015 3:30 pm

Is one of you guys from germany? I'd be willing to swap your adaptor for mine to see if i can fix it.

I'd assume opening and cutting the right wire (the 5v supply going to the vga connector) will fix this.

TillDawn · Post by **TillDawn** » Sun May 10, 2015 3:59 pm

MasterOfGizmo wrote:Is one of you guys from germany? I'd be willing to swap your adaptor for mine to see if i can fix it.
I'd assume opening and cutting the right wire (the 5v supply going to the vga connector) will fix this.

Yes, I'm from Germany. I will send you a PM.

MasterOfGizmo · Post by **MasterOfGizmo** » Mon May 11, 2015 7:16 pm

Mine is on its way to you ...

TillDawn · Post by **TillDawn** » Tue May 12, 2015 8:25 am

I sent mine yesterday, as well. Will arrive today, probably.

Gryzor · Post by **Gryzor** » Tue May 12, 2015 8:27 am

My Sandberg converter arrived today... can't wait to try it out!

TillDawn · Post by **TillDawn** » Tue May 12, 2015 2:05 pm

I just received Till's adapter and, unlike like the one I sent to him, it works perfectly with my MiST. I tested it with the Atari ST core, 50Hz and 56Hz, both no problem. No powerdown with connected USB, really great picture over HDMI. So, that apparently means that there are at least two hardware variants of the Sandberg adapter. Hopefully, there is a solution to that problem. Picture quality is really good and it would be a shame if the power issue would prevent people from using it.

Gryzor, hopefully the one you bought is the working variant.

Till, shall we swap again after you have investigated the issue?

Newsdee · Post by **Newsdee** » Tue May 12, 2015 2:54 pm

Would be worth opening it to check the chips, but it might not be possible to do so without destroying the plastic.

I've seen an adapter at Maplin's during a trip to the UK; they didn't know what was inside but the layout is identical to one of mine. So pretty sure it has the MS9282... http://www.maplin.co.uk/p/vga-to-hdmi-c ... port-n47hh

Gryzor · Post by **Gryzor** » Tue May 12, 2015 5:27 pm

Unfortunately my MiST is not available to check it, I'll do it as soon as I get it back. Anyone has kept their packing material by any chance? Mine says Item No. 508-78, barcode 5705730508783. Maybe different models have different codes...

And yes, I can't seem to find a way to open it, I think the plastic is melt together...

TillDawn · Post by **TillDawn** » Wed May 13, 2015 8:13 am

Gryzor wrote:Anyone has kept their packing material by any chance? Mine says Item No. 508-78, barcode 5705730508783. Maybe different models have different codes...

And yes, I can't seem to find a way to open it, I think the plastic is melt together...

The one that I bought and that did not work had the same item no. and barcode. I bought mine 3 weeks ago on Amazon Germany. The enclosure indeed seems to be very sturdy; opening it will most likely damage it permanently, I guess.

Gryzor · Post by **Gryzor** » Wed May 13, 2015 8:21 am

Thanks. Now, if we only had the info from a working one... (which would probably be the same, but just checking)

Gryzor · Post by **Gryzor** » Wed May 13, 2015 8:24 am

MasterOfGizmo wrote:Hi. That's bad news as this means that your adapter tries to source power from the vga connector. It seems the pin it uses for that is connected to gnd on the mist. This will shorten any usb power supply.

That means the adapter you have is not identical to mine ... i'll think of a solution.

Does this mean that if the MiST is NOT powered from the micro USB plug it will work ok?

MasterOfGizmo · Post by **MasterOfGizmo** » Wed May 13, 2015 7:22 pm

No. The mist needs to be powered.

The problem is that I connected pin9 on the VGA connector to gnd. Some versions of the adapter connect this pin to 5v on use and this creates a short circuit. In the meantime I received one of these. I carefully broke pin 9 of its VGA connector and now it works just like the one I had before.

Gryzor · Post by **Gryzor** » Thu May 14, 2015 6:11 am

MasterOfGizmo wrote:No. The mist needs to be powered.

The problem is that I connected pin9 on the VGA connector to gnd. Some versions of the adapter connect this pin to 5v on use and this creates a short circuit. In the meantime I received one of these. I carefully broke pin 9 of its VGA connector and now it works just like the one I had before.

Maybe it's a bit early and caffeine is not working just yet for me, but... of course I know the MiST needs to be powered

What I meant was, I'm having a power plug installed, instead of powering it from the USB.

But it's good to know there's a solution, though how did you manage to break pin 9, which is not at the edge, is beyond me!

T

PS from what I read pin 9 is +5V normally, so technically speaking isn't the converter designed correctly?

MasterOfGizmo · Post by **MasterOfGizmo** » Thu May 14, 2015 8:21 am

I grabbed it firmly with this kind of tool:

Then i rotated the pin until it broke off:

vga_con.jpg

Gryzor · Post by **Gryzor** » Thu May 14, 2015 3:21 pm

Ahhh rotation. If it worked for trashing my knee in basketball, it will work for a pin 9

Or, my friend who does the mod for me suggested not actually wiring pin 9 (I'm having the VGA removed and reattached a few cm away on the box), would that cause any troubles down the line? But then again, if the adaptor is trying to source power through pin 9 and 9 is not connected, how is it powered?

MasterOfGizmo · Post by **MasterOfGizmo** » Thu May 14, 2015 5:08 pm

It's supplied via usb. If you let your friend connect pin 9 to 5v then you could power the device via vga without using the usb connection at all.

And yes, it's probably fine what the adapter does on pin 9. Connecting it to gnd wasn't clever by me.

Gryzor · Post by **Gryzor** » Thu May 14, 2015 5:21 pm

MasterOfGizmo wrote:It's supplied via usb. If you let your friend connect pin 9 to 5v then you could power the device via vga without using the usb connection at all.

And yes, it's probably fine what the adapter does on pin 9. Connecting it to gnd wasn't clever by me.

Wait, I'm a bit confused now, so let's take it a bit slowly if you don't mind

-There are two variations, one that gets power on the 9 pin, and one that doesn't (9 is GND or not connected? And what pin is power?).
-the second one works with MiST just fine, the first one shorts the board and it won't boot.
-disconnecting pin 9 in the first version will solve that problem, however what happens if you disconnect pin 9 on the second version?
-you say, "it's supplied via USB". In which case?
-you also say "if you...connect pin 9 to 5V then you could power the device via VGA", which is very coo, but... then the MiST won't boot?! Not sure if that's an advice from your part or you're just mentioning it in the frame of different setups (not MiST).

So in effect, my dilemma is, I have the converter, I don't know which version it is, and my MiST is away. Is there a method I should choose?

Regarding pin 9, well, we live and learn

The board has given me so much joy such small niggles are of no consequence...

And I'm grateful for your replies!

MasterOfGizmo · Post by **MasterOfGizmo** » Thu May 14, 2015 8:35 pm

There seem to be two versions.one takes power from USBand the other one will use either VGA or USB or both of them. Now unfortunately I connected the pin on VGA that usually provides 5v to gnd. If you now connect the adapter that can take its current from both of the you get a short circuit. This happenns since 5v enters from USB, goes though the adapter but is connected to gnd on the VGA side.

I should have left pin 9 unused as I didn't intend to use it. I could have connected it to 5v to help powering external devices. But the one thing I never expected is that devices would expose their own power source via this pin. It's unexpected for a device to do that but not necessarily wrong....

MasterOfGizmo · Post by **MasterOfGizmo** » Thu May 14, 2015 8:38 pm

Regarding your board: If you ask your modder to connect VGA pin9 to 5v _instead_ of gnd. Then your board will work as before but you won't have the short circuit with this converter anymore. Instead you can even power the HDMI converter over it.

There will be no negative impact to be expected in any way.

Gryzor · Post by **Gryzor** » Sat May 16, 2015 3:25 pm

Ok, I think I see, with my friend's help too, so thanks!

Do we know how many mAh's the HDMI converter draws? After all this will have to be added to everything else powered from the same source...

MasterOfGizmo · Post by **MasterOfGizmo** » Sat May 16, 2015 7:39 pm

It seems to draw close to 200mA.

Gryzor · Post by **Gryzor** » Sun May 17, 2015 7:25 am

Ah, 200mAh is ok for our purposes I guess.... thanks for the info!

Gryzor · Post by **Gryzor** » Sun May 17, 2015 8:14 am

By the way, I can't find the thread we were talking about the power consumption of the MiST itself. Int his thread (1st page) you say that the adapter+MiST does not exceed 500mA, does the MiST really only draw 0.3A?

In any case with my 2A PSU I guess I'm fine

MasterOfGizmo · Post by **MasterOfGizmo** » Sun May 17, 2015 8:47 pm

Yes, pretty exactly 300mA for a typical setup incl. a USB mouse, gamepad and keyboard.

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