DLP780NEEVM: Unexpected vertical line issue

Hello Jong Hwan,

I am sorry to hear you're having issues with this! Thank you so much for providing photos and an investigation breakdown. If you have another DMD are you also seeing this when replaced? Or if you have another set of EVMs, have you tried swapping the boards?

Yes, vertical lines on the DMD is an indication that there is a signal integrity/input issue on the LVDS signal to the DMD.

I would recommend you investigate the FMC connector pins and ensure that they are still intact. Maybe perform a continuity test on the DMD EVM while probing the top/bottom.

I am fairly confident this issue would follow the EVM due to connector/connection issues.

Best,

Aaron

Hi Aaron,

Thank you for your detailed support.

Since I don't have another EVM to test with, I attempted to reconnect the boards directly and restart from boot loader without the ribbon cable.
Unfortunately, that didn't resolve the issue.

As background, I had previously replaced the DLPC4430EVM due to a connection issue with the computer.

The situation is detailed in the following post:
https://e2e.ti.com/support/dlp-products-group/dlp/f/dlp-products-forum/1399687/dlpc4430evm-connection-issue

I now have a few follow-up questions:

1. Could you please advise on how to perform a continuity test? Specifically, which test points or pins should I check?

2. In the situation mentioned above, I only replaced the DLPC4430EVM. Could this affect the operation of the DLP780NEEVM?

3. If there's no viable solution such as repair or reconfiguration, would I need to replace all the EVMs?

I look forward to your guidance.

Best regards,
Jong Hwan

Hello Jong,

Our apologies, but the forums were down for maintenance on Friday (7-11).  Aaron is out on holiday for the next couple of days.

Is your current EVM/DMD board arranged as shown in the linked thread? or do you have a Samtec extension cable between the controller board and the DMD board?

Fizix

Hi Fizix,

Thank you for your explanation.

Just to clarify, I'm currently using the EVMs with a Samtec extension cable, as shown in my initial post ("Line issue.pptx").
I also tried connecting them directly without the extension cable, but the same issue still occurs.

Do you happen to know any other possible solutions for this problem?

Looking forward to your response.

Best regards,
Jong Hwan

Hello Jong Hwan,

Could you please turn off the system and try re-seating the DMD? Please check that the pins are straight and none are bent.

Best,

Aaron

Hi Aaron,

I configured the DMD setup as described in the 4430EVM user guide, including removing the extension cables and assembling everything on a flat surface. I also cleaned the connection pins, but the issue still persists.

At this point, I suspect that the problem might be related to the circuit or one of the components. Could you advise which test points I should check to further check the issue?

Also, if the issue remains unresolved after testing, I'm considering replacing the EVM board. In that case, could you let me know which board is more likely to be the root cause or more critical to the system operation?

Thank you for your support.

Best regards,
Jong Hwan

Hello Jong Hwan,

I would recommend you replace the DMD EVM first and then the formatter board.

I would suggest to check the LVDS Bus C and D High-speed differential pairs and ensure they look all the same. For example - place a probe on B18 [D_CN(0)] and another on B19 [D_CP(0)] and ensure they are toggling at the same time although they should be opposite to each other, then move onto D_CN(1) and D_CP(1).

Best,

Aaron

Hello Aaron,

Thank you for your response! I’ve reviewed the suggestions, and it seems that replacing the board would be the best option.

I was wondering if it might be possible to purchase a replacement at a slightly reduced price or exchange it by returning the board we currently have. Could you kindly check if this option is available?

Thank you in advance for your help.

Best regards,

Jong Hwan.

Hello Jong Hwan,

I understand you're looking to replace this EVM but I need to look back on a point that I did not ask about previously.

Are these lines staying on the DMD when not operational or is it just while the DMD is in operation?

Best,

Aaron

Hello Aaron,

Thank you for confirming that clearly!

The lines as we mentioned earlier only appear when the 4430EVM is connected to the 780NEEVM and HDMI, with the power turned on.

(There's no lines when DMD is not operational.)

If you have any additional information regarding this, I would really appreciate it.

Best regards,

Jong Hwan.

Hello Aaron,

If I may ask one final question before we proceed with the E2E process — Is there any possibility of receiving a discount by returning or exchanging the board we currently have, as previously discussed?

Best regards,

Jong Hwan.

Hello Aaron,

Thank you for your kind explanation!

However, our experiment using the DMD chip is on a tight schedule, so I would appreciate a prompt response if possible.

If possible, I’d like to make a decision regarding return or repair within this week. Also if repair is not feasible, I’d prefer to proceed accordingly and repurchase the device.

Best,

Jong Hwan.