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Blackened

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Joined: 11/08/2012
Location: Australia
Posts: 66

Posted: 05:11pm 27 Aug 2013

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Hey all, I'm having trouble with my 12V LCD monitor plugged into the composite out.

Initially I had a totally garbled screen output. I noticed that there was a couple of components (suppressor??) that I'd abandoned, that were attached to the power input socket on the ATX power supply casing, so I wired them back in and now I've got a slow vertical scroll. Noisy power supply?

I powered the monitor from a small 12V plug pack, and a DVD player displays fine. I plugged the DM into a TV via composite and while the image was a little contracted, it was steady and clear.

But put the two together and no good. The DM is powered from 5V.

I guess my next step is to try a different power supply for the DM but I've run out of tinker time today. Is 5V enough for the composite out?

Thanks everyone. You've all been really helpful with all my questions

Blackened

Regular Member

Joined: 11/08/2012
Location: Australia
Posts: 66

Posted: 03:24pm 28 Aug 2013

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Ok a little more information.

MMbasic 4.4 on both a DM mega and standard DM.
All sorts of power supplies tried.

I get a slow scrolling output on the 7" LCD screen no matter what I do. My screen is identical to Greg Fordyce's monitor shown in another thread here

Maybe I need one of those VGA to composite adapters. I've read through the DM documentation that I have and I don't see any mention of the composite only working with CRTs etc.. Maybe I missed something?

I retested the monitor on a DVD player and it displays fine.

MicroBlocks

Guru

Joined: 12/05/2012
Location: Thailand
Posts: 2209

Posted: 10:26pm 28 Aug 2013

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Look for a 'vertical hold' adjustment. You might need to open it.
I guess the timing is just a little out of acceptable range for that particular LCD. Even with same types this can happen.

Microblocks. Build with logic.

Blackened

Regular Member

Joined: 11/08/2012
Location: Australia
Posts: 66

Posted: 01:53am 29 Aug 2013

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Thanks TZ!
I thought the old V-Hold adjustment went the way of the Dodo a looooong time ago.

The first thing I thought when I saw the scrolling was "if this was the old B&W TV we had I'd just fiddle with the V-Hold knob" but dismissed the thought as ridiculous DOH!

I had no idea the principal (whatever the details may be) applied to LCD technology.

I'll rip the cover off when I get a chance and have a look.

Much appreciated

Blackened

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Joined: 11/08/2012
Location: Australia
Posts: 66

Posted: 04:26pm 29 Aug 2013

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Bugger!! No trimpots to be found!

For those of you in the know, is there any component alteration/addition I could make to the DM to give me the required "V-Hold" adjustment? Could I solder a trimpot across a couple of track/pins whatever?

I have a VGA to composite adapter on it's way from China so I'll give that a go when it turns up. Even if I don't need it for the DM it'll come in handy I'm sure.

Thanks again everyone!

MicroBlocks

Guru

Joined: 12/05/2012
Location: Thailand
Posts: 2209

Posted: 10:07pm 29 Aug 2013

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Out of luck with that LCD.
It is not easy to change the video signal, the only place is in the MM firmware.

The LCD probably uses a cheaper crystal or resonator that causes it to be unable to lock on the video signal.
You could change the crystal or resonator with a more accurate value. Many LCDs use crystal frequencies that are more common and cheaper.
Should not cost you more then a few dollars to try that.

Microblocks. Build with logic.

Blackened

Regular Member

Joined: 11/08/2012
Location: Australia
Posts: 66

Posted: 04:34am 30 Aug 2013

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Thanks again TZ.
I've just requested the source code. I partially completed a C programming course many moons ago. I guess it can't hurt to have a look. I've always felt a bit more at home with the software side of things than I have with the hardware. Now to go hunting for the courseware and I'm pretty sure there was a copy of a Borland "something or other" IDE.

What's the worst that can happen??? No, don't answer that!

BobD

Guru

Joined: 07/12/2011
Location: Australia
Posts: 935

Posted: 07:23am 30 Aug 2013

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Are you running the composite video in PAL mode or NTSC mode? It may be worth a try of both if you haven't already done it. In monochrome the differences between the two may only be timing.

The other possibility is a ground current on the composite cable. Try (if you can) connecting the composite cable with a ground connection at one end only. Does the display work OK on the DM if you power it from the plug pack?

JohnS
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Joined: 18/11/2011
Location: United Kingdom
Posts: 4038

Posted: 10:00am 30 Aug 2013

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Forget Borland. Not useful here.

John

Blackened

Regular Member

Joined: 11/08/2012
Location: Australia
Posts: 66

Posted: 01:54pm 30 Aug 2013

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BobD said Are you running the composite video in PAL mode or NTSC mode? It may be worth a try of both if you haven't already done it. In monochrome the differences between the two may only be timing.

The other possibility is a ground current on the composite cable. Try (if you can) connecting the composite cable with a ground connection at one end only. Does the display work OK on the DM if you power it from the plug pack?

Thanks for the suggestions BobD, yeah tried NTSC and PAL. Also tried powering both the DM and monitor with an assortment of different power supplies, both separately and combined. Either device works ok using another form of input/output, but together they don't play nice. I'll have a look at possibly disconnecting the ground on one end when I have a chance.

bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2949

Posted: 05:52pm 30 Aug 2013

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Blackened said The DM is powered from 5V.

Hi Blackend,

Is it the DM mini you are using? If not the power input must be higher than 5V... only the DM mini will accept (and in fact MUST be) +5V.

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

Blackened

Regular Member

Joined: 11/08/2012
Location: Australia
Posts: 66

Posted: 08:56pm 30 Aug 2013

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bigmik said
Hi Blackend,

Is it the DM mini you are using? If not the power input must be higher than 5V... only the DM mini will accept (and in fact MUST be) +5V.

Regards,

Mick

Thanks Mick,
No, just the Standard DM, and I've tried a Mega too. I've not had any trouble powering either with 5V via the USB socket, but I did try a 9V plugpack on the alternate power input but didn't have any luck. Everything else seems to be working ok, just the V-Hold issue.

On a side note, how did I spend an entire day putting 5 LEDs in the front case of my project?? And I still didn't get them all wired in to their respective outputs. Maybe I should get my tools more organised. "where did I put the heat shrink??, I just had it in my hand!!".

bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2949

Posted: 03:36pm 31 Aug 2013

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Blackened said I've not had any trouble powering either with 5V via the USB socket, but I did try a 9V plugpack on the alternate power input but didn't have any luck.

Hi Blackened,

Sorry I misunderstood... Of course 5V through the USB is fine, I did mean through the power jack... DM is 7.5 -30V input on power jack EXCEPT DM-Mini which is 5Vdc ONLY..
So yes you have it powered correctly...

Blackened said Everything else seems to be working ok, just the V-Hold issue.

You do have the DM configured for composite out dont you? I assume so as you plugged it into a TV.. But if configured as VGA then composite output wont `sync'

Blackened said On a side note, how did I spend an entire day putting 5 LEDs in the front case of my project?? And I still didn't get them all wired in to their respective outputs. Maybe I should get my tools more organised. "where did I put the heat shrink??, I just had it in my hand!!".

HeHe... I have those days... nowadays its more often than not that I am disorganised...

PS. Does your username TAG reflect the above moments??

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

Blackened

Regular Member

Joined: 11/08/2012
Location: Australia
Posts: 66

Posted: 11:30pm 31 Aug 2013

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Hey Bigmik,

Regarding configuring for composite out. Other than "Config composite pal", is there any other software or hardware preparation on the DM that I might not be aware of? I'm using the DM with the optional I/O board.

Blackened was once a favorite song of mine. I've moved on from Metallica but the name has stuck. It relates well to various home brewing failures too!!

Oh and in my defence of the LED saga

, I spend about 2 hours trying to get a sticker to print out properly. My daughter and wife both suggested a bottle or bottle cap should feature on the front of the controller. The caps have the LED+bezel in the center, and the bottle laying on its side, points to the LED and the text label is inside the bottle. Seemed appropriate for a home brewing computer but I'm no artist and it took me forever! But most of the time was spent looking for tools yes.

bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2949

Posted: 12:08pm 01 Sep 2013

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Blackened said Hey Bigmik,

Regarding configuring for composite out. Other than "Config composite pal", is there any other software or hardware preparation on the DM that I might not be aware of? I'm using the DM with the optional I/O board.

Hi Blackened,

Sorry, I cant be of more help... I reckon that should be ok but as I dont use composite I am not able to definitively say that that is all that is required.

It is looking like an incompatibility with your monitor..

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

VK2MCT
Senior Member

Joined: 30/03/2012
Location: Australia
Posts: 120

Posted: 01:21pm 06 Sep 2013

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Does anyone know the field and line frequency from the composite out of the DM.
Just wondering?

John B
VK2MCT

BobD

Guru

Joined: 07/12/2011
Location: Australia
Posts: 935

Posted: 01:42pm 06 Sep 2013

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John, to be useful it would have to match the TV standards for PAL and NTSC. You can read about it here.

VK2MCT
Senior Member

Joined: 30/03/2012
Location: Australia
Posts: 120

Posted: 04:45pm 06 Sep 2013

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Thanks Bob,
I'm am wondering how close the DM frequencies are to 625 frequencies (pendantly - can't refer as PAL, cause there is no colour subcarrier to switch each alternate line).
FWIW I have recently retired from a techo role at a TV station. Oh dear, I can still remember 4.43361875Mz+-5Hz as subcarrier freq.

John B
VK2MCT Edited by VK2MCT 2013-09-08

lazy-b
Newbie

Joined: 26/02/2015
Location: Philippines
Posts: 2

Posted: 07:49pm 24 Mar 2015

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Guys, I am using Duinomite Mini and make my own a VGA to RCA adaptor so that I could use a regular composite TV Monitor .

It work perfectly using on my LCD monitor using Pal setting, but when I plug it to a CRT TV NTSC video input, you can see a image rolling vertically.

How do I set the Duinomite Mini to NTSC mode ?

Frank N. Furter
Guru

Joined: 28/05/2012
Location: Germany
Posts: 947

Posted: 08:15pm 24 Mar 2015

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Hi,

did you tried "CONFIG COMPOSITE NTSC"?

Frank

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