FAQ
TL;DR: 1/1 board-swap confirmed a main-board failure on this Xiaomi; “defect is on the main board.” If your L43M5-5ASP shows colored dots with no OSD, use this guide to isolate the bad board. [Elektroda, smartec, post #21217384]
Why it matters: This FAQ helps bench techs and DIYers triage colored-dots/no-OSD faults and choose the right board to replace.
- Chassis TD.MS6886.793; panel LVU430CSDX E0001; T‑Con ST4251D01‑3‑C‑3. [Elektroda, smartec, post #21188655]
- Symptom snapshot: TV powers on but shows colored dots instead of an image. [Elektroda, smartec, post #21186624]
- No OSD despite remote input; user couldn’t select HDMI. [Elektroda, smartec, post #21188438]
- First-line triage shared in thread: “1st > change T‑con.” [Elektroda, lisek, post #21189344]
- CPU rails to verify: ~1.2 V, ~1.5 V, and 3.3 V from DC‑DC converters. [Elektroda, Mario19593007, post #21617902]
Quick Facts
- Chassis TD.MS6886.793; panel LVU430CSDX E0001; T‑Con ST4251D01‑3‑C‑3. [Elektroda, smartec, post #21188655]
- Symptom snapshot: TV powers on but shows colored dots instead of an image. [Elektroda, smartec, post #21186624]
- No OSD despite remote input; user couldn’t select HDMI. [Elektroda, smartec, post #21188438]
- First-line triage shared in thread: “1st > change T‑con.” [Elektroda, lisek, post #21189344]
- CPU rails to verify: ~1.2 V, ~1.5 V, and 3.3 V from DC‑DC converters. [Elektroda, Mario19593007, post #21617902]
How do I fix a Xiaomi L43M5-5ASP that shows colored dots instead of an image?
Start by replacing or testing with a known‑good T‑Con board. This was the first repair step recommended in the thread. If the symptom remains after a T‑Con swap, continue with main‑board isolation. Use careful ESD handling and reseat flex cables during the test. Document before/after photos for traceability. “1st > change T‑con.” [Elektroda, lisek, post #21189344]
Could colored dots just be analogue “no signal” snow?
Yes, the artifact can resemble analogue no‑signal snow. One reply specifically noted that similarity. To differentiate, try to bring up OSD or menus. If OSD renders normally, you may be seeing an input/no‑signal condition rather than a hardware fault. If OSD does not render, continue hardware diagnostics. [Elektroda, DiZMar, post #21186947]
The TV powers on, remote works, but no menu appears—what does that point to?
In the case reported, “It doesn’t display any graphics,” yet the set responded to the remote. That behavior suggests a video‑path failure beyond simple input misconfiguration. You may be unable to select HDMI sources or see volume overlays. Proceed with T‑Con testing, then isolate the main board if unchanged. [Elektroda, smartec, post #21188438]
How can I confirm the main board is bad on this model?
Board swapping is decisive. The OP verified the fault by testing with another set and concluded the main board was defective. “Defect is on the main board.” How‑To: 1) Install a known‑good main board or test your board in a donor. 2) If the fault follows the board, it’s bad. 3) Then inspect SoC, DDR, or storage. [Elektroda, smartec, post #21217384]
What exact boards and panel are inside the unit discussed here?
Reported hardware: chassis TD.MS6886.793, panel LVU430CSDX E0001, and T‑Con ST4251D01‑3‑C‑3. Use these IDs when sourcing parts or checking compatibility. Verify sticker revisions on your unit, as sub‑revisions can differ. Photograph labels before ordering to prevent mismatches. [Elektroda, smartec, post #21188655]
Which processor does a similar chassis in this family use?
A closely related chassis uses the MStar MSD6886 SoC, a quad‑core Cortex‑A55 at about 1.4 GHz. This context helps when assessing thermal behavior and voltage rails. Cross‑reference donor boards listed under the same MS6886 platform when sourcing parts. [Elektroda, lisek, post #21188472]
Could the fault be eMMC or the processor?
One diagnosis points to issues with DDR or the BGA bus between the processor and DDR, not necessarily eMMC. Inspect for intermittent memory access or reflow‑sensitive behavior. “Probabile che sia qualche DDR o i collegamenti BGA del bus tra processore e DDR.” Consider memory rail stability before advanced rework. [Elektroda, Mario19593007, post #21264100]
My set reboots after 5–7 minutes and the CPU heatsink is scorching—what does that indicate?
This symptom was reported: after 5–7 minutes the image freezes, no remote response, then a reboot. The heatsink felt extremely hot. That pattern points to SoC stress or a power integrity problem under thermal load. Confirm with temperature monitoring and controlled cool‑down tests to reproduce. [Elektroda, leszekkiepiski, post #21616819]
What voltages should I check around the SoC during crashes or overheating?
Measure all CPU‑related DC‑DC rails. Typical rails are about 1.2 V and 1.5 V for the core/memory, plus 3.3 V. Verify each regulator under load and during warm‑up. “Dovresti controllare tutti i DC‑DC sulla scheda… le tensioni si raggirano intorno a 1,2V, 1,5V… come pure la 3,3V.” Compare against a good board if available. [Elektroda, Mario19593007, post #21617902]
If changing the T‑Con does not help, what’s the next suspect?
Move focus to the main board. In this case, a board swap confirmed the defect on the main board, not the panel. Inspect SoC, DDR, and storage, and verify power rails before rework. Prioritize clean reflow environments if BGA work is needed. [Elektroda, smartec, post #21217384]
What T‑Con module should I order as a test part for this unit?
For the reported unit, the T‑Con board is ST4251D01‑3‑C‑3. Match the full code on your board, as suffixes matter. Order from a reputable supplier and confirm return policy in case the fault resides elsewhere. [Elektroda, smartec, post #21188655]
Will the TV still respond to the remote during this fault?
Yes. The reported unit responded to the remote but showed no menus or overlays. The user could not select HDMI sources to test audio. This indicates logic activity without proper video output. Use this clue to guide hardware checks. [Elektroda, smartec, post #21188438]
Is there a similar chassis I can cross‑reference for donors or documentation?
Yes. A very similar model with chassis TPD.MS6886.PB792 was cited, using the same MS6886 platform. Cross‑checking these references can help find donor boards, T‑Con notes, or service data. Always verify connectors and firmware compatibility. [Elektroda, lisek, post #21188472]
Any visual symptom that can mislead diagnosis?
Yes. Colored‑dot artifacts may resemble analogue no‑signal snow at first glance. Don’t stop at input checks; verify OSD rendering and proceed with board‑level tests if OSD is absent. This avoids chasing tuning issues when hardware is faulty. [Elektroda, DiZMar, post #21186947]
