Quirk about the ADC Connector

I started having problems with the ADC display using the adapter I built. It worked fine for quite some time then the display started to shut itself off and not be recognized by the system. Sometimes it would work to plug the cables back in.

At first I thought it was the power supply I was using. I don't have specs on it, but the problem surfaced when the temperature climbed. The computer area was hovering around 90°F, and I assumed the power supply was sporadically failing. I bought a new-to-me 24V 1.8A supply for my 17" monitor (I think that might be a bit on the low-side, but it was only a couple dollars at a thrift store.) The problem persisted almost immediately. So I figured the monitor might be fried.

The ADC connector shield is loose.

The ADC connector shield is loose.

I had noticed the shield on the ADC connector on the board was not connected to the ground very well. I didn't think much of it — after all, there were half a dozen ground wires already. But on a whim, I thought I'd add a couple dabs of solder and give it a solid connection to the pins soldered onto the board. Surprisingly, that did the trick. So far it's been 2 days and the monitor has not flaked out! It may be the power supply is on the low-side to begin with (24V) and without the additional ground of the shield, the voltage drop crept too high in the other wires for the monitor to function.

ADC connector shield.

ADC connector shield.

In any case, if you are observing sporadic problems where the monitor would shut off, apparently losing power, check the shield on the ADC connector and make sure it has a solid ground.

Solder added to ADC connector shield.

Solder added to ADC connector shield.

Update August 7, 2013: Not so fast. I am still having problems where the monitor will switch off and not come back on. Most recently, I had to unplug the power for 15 minutes as well as the connection to the computer before it came back to working. I'm not sure what it is, but the ground is not the only fault going on here …

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ADC Adapter Board with Minor Bugs

I finished up my ADC-DVI-VGA version that fits in an Altoids tin and sent it to BatchPCB. I prefer to use American labor, so I got a quote from Advanced Circuits, but the prices work out: it’s about $400 to start at any quantity (e.g. 10 is about $40 each) down to $10/each for 100. I couldn’t justify it in case (a) there was a bug, and (b) whether I could sell more than 5 to make up for it.

While I was waiting for it, I fiddled around in the design to make sure it was right. I realize I should have checked the design first, and, running the electrical rule check (ERC) I found I had left the DVI connector ground unconnected. D'oh! Fortunately there are half a dozen other grounds which (usually) get all tied together, so I was lucky and when I wired one up, it worked perfectly the first time. (Note that this is the 2012-Feb-29 version with only 4 copies around.)

I'm updating the design and will send it off to BatchPCB and open it up for sale. I'll also post the design files as my intent is for this project to be an Open Source Hardware (OSHW) project.

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