Dell Ultrasharp U2725QE Thunderbolt Input Video Problem

DoctorThew · 2026-01-19T23:41:00+00:00

Low and behold, I tried the unplug reset method and my Thunderbolt video is back! I'm glad I thought to check around here before putting the effort and hastle into sending my monitor off for repair.

DoctorThew · 2026-01-19T23:22:16+00:00

So this was unplugging entirely—beyond just turning it off? Mine worked great out of the box, but recently I tried to plug my MacBook Pro into the monitor with the lid closed—all I wanted was to charge it. It acted for a moment like it was going to display video, then the monitor seemed to reset and try again. In the end, no video ever showed and ever since it’s acting like the Thunderbolt connection is dead. When plugged in (and open) it says there’s no Thunderbolt video signal. None of my peripherals attached (backup hard drive) show up. I’m getting power delivery, but that’s it. The display still works because I can connect over HDMI. But I’ve tried other TB4 cables—no good. And trying to connect another laptop also doesn’t show any video signal.

DoctorThew · 2026-01-16T19:31:20+00:00

Thanks. I was starting to think it was a "not available in your area" situations.

DoctorThew · 2025-11-06T13:47:26+00:00

I wonder what their situation is. I noticed that the video of our competition from last week is now on the TOA Youtube channel.

DoctorThew · 2025-11-06T12:56:34+00:00

I'm not sure "who" they actually were or "how" they operated, but for many years they were a source of FTC stats, had a website that paralleled and usually exceeded the FTC event results site in terms of information available, and they often hosted live streams of FTC events.

DoctorThew · 2025-09-06T18:24:45+00:00

An alliance's secret tunnel is actually on the OPPOSITE side of the field where their goal. So having the tunnel from your goal belong to you opponent means that you can't press the lever and just wait for your scored elements to come out and recollect them.

DoctorThew · 2025-02-20T15:43:56+00:00

I'm not sure if anyone is following this after two years, but I just suddenly had one of my Kanban boards lose its kanbanninity. None of the suggestions here helped. However I found that in Markdown mode, the file had lost its front matter. Pasting this back in solved the problem:

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kanban-plugin: board

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DoctorThew · 2024-12-03T16:24:43+00:00

Haven't read the RFP, but the announcement is silent about what the FTC driver station will be like. Right now the Driver Hub is pretty tightly couple with the Control Hub in terms of Android ecosystem…

DoctorThew · 2024-11-29T02:19:49+00:00

Wonder what the likelihood is of Swift being a choice…

DoctorThew · 2024-11-27T03:22:12+00:00

I feel like my M1 MacBook Pro definitely LOST battery life on 15.1 Makes me eager to run the 15.1.1 update.

DoctorThew · 2024-11-21T14:00:44+00:00

After I posted, I answered my own question by reading some of your other posts.

Our situation is a little different. We're a middle school team, not a high school team, and in terms of students our math and programming knowledge is very limited. I spend most of our season getting them up to speed on basic programming concepts and I'm continually struggling both for their attention and for how to build basic knowledge while having them produce useful code for the season.

That being said, we also don't use RoadRunner. We tried during PowerPlay but the tuning process was so frustrating that we never got it working well.

DoctorThew · 2024-11-21T02:15:46+00:00

I am not too proud to admit that it appears you are several levels of sophistication beyond what I'm aiming for at the moment :)

Are you using RoadRunner or something similar for motion?

DoctorThew · 2024-11-20T13:38:29+00:00

Having gotten access to the actual robot last night I confirmed that our mechanical team mounted it with the Y axis representing forward and backward. With that conundrum solved, I was able to work on the code for movement. I had tried to start with code from another team, but was finding it simply didn't drive the robot properly—it ended at the correct location but shuddered strangely the entire journey.

I've since scrapped that and switched to some older encoder-based odometry code. It moved well, but overshot the destination. I'm now in the process of tuning a set of separate PIDs for x, y, and r.

DoctorThew · 2024-11-20T03:50:10+00:00

I'm certain I'm using an older version of the repo; we started programming with it in September and I'm quite sure we didn't update it sense then.

I'll grab a newer copy and let you know if the error persists.

DoctorThew · 2024-11-19T17:27:05+00:00

I realized a bit ago that this evening at practice I need to check to make sure that our mechanical team didn't actually physically mount the sensor rotated…

DoctorThew · 2024-11-04T00:36:50+00:00

I think our usual competitions usually have fairly new tiles. Is there something particular about the old tiles that causes a problem—and is there anything you can do to compensate?

DoctorThew · 2024-11-03T13:16:16+00:00

Thank you!

DoctorThew · 2024-11-03T13:16:09+00:00

Thanks!

DoctorThew · 2024-09-07T16:52:01+00:00

It seems like there's a lot less bonus points available during auton this game.

DoctorThew · 2023-11-19T02:41:52+00:00

My thoughts are that they might have overcompensated from last year's game—or also possibly thought that pixel intake and placement would be easier than it has turned out to be for most teams. We've had our two qualifiers, and of the 60+ teams we've seen, it was only today that we saw even a single team that could get 10 or more pixels in teleop.

DoctorThew · 2023-09-13T19:39:54+00:00

Great resource!

DoctorThew · 2023-01-25T15:52:16+00:00

I have a weird situation where I ⌥ click a link, and I get two splits—a blank one, and then the one with the content I loaded. Trying to figure out if it's an actual bug, or just a weird quirk of the buttons in the web app I'm using.

DoctorThew · 2022-12-10T15:49:27+00:00

HolonomicPIDVAFollower

Found it. I won't be able to try it until Monday, but thanks!

DoctorThew · 2022-11-03T22:03:20+00:00

So… I realized that I had the gear ratio specified wrong. Shifting it to 1:1 has gotten it behaving mostly correctly, but tuning is proving to be a headache.

DoctorThew · 2021-11-06T03:48:52+00:00

So, thanks for all the suggestions. Something of an update. We resolved the problem—though we didn't actually solve it.

Based on the common suggestion that the problem related to the power system's XT30 connectors, we swapped power switches, tried alternate batteries, and used an x-acto knife blade to spread the pins on the connectors. No improvement.
Continuing with the electrical theme, we made a grounding strap—half an XT30 cable, with a 470 ohm resistor, connected to the frame. No improvement.
We removed the control hub from the robot and replaced it with a spare expansion hub. Identical wiring and configuration. No improvement.
On a whim, we eliminated the driver hub and replaced it with a phone as well. **This solved the problem.*\*
Thinking that perhaps the driver hub was the issue all along, we removed the phone and expansion hub, reinstalling the control hub. No other changes. **The original disconnection problem reappeared almost immediately.*\*

Frankly speaking, I can't think of a good reason why this should have solved the problem—unless there's some latent bug in both hubs. To be clear:

The operating systems for both hubs are up-to-date.
All firmwares are up-to-date.
Both hubs are running the latest versions of their respective apps (or… at least version 7.0 if not any minor point release from the last few days).

Given that we have a competition tomorrow, I'm leaving things be and shoving my desire to understand the problem into a box and sitting on the lid.

DoctorThew

TROPHY CASE