Monitor doesn't display but lights up.

Question

ディスプレイの

ビデオ出力付きのPC用ディスプレイ(もしくはモニター)の修理ガイド

506回答すべてを表示

CRUDOfromBHM @kundro

評価: 10

3

投稿日: 2023年3月16日

オプション

Monitor doesn't display but lights up.

Hi,

Monitor: Millenium MD34
Panel: Samsung LSM340YP05
Control board: MST9835RN-EDP
TCON board: CCPD-TC-340-001

I'm trying to repair broken display, the display turns on the backlight and act logical (turn on backlight to display manufacturer logo, turn off to sleep///turn on backlight when plugging signal(HDMI/DisplayPort) and don't sleep) - it doesn't display anything on the screen, it just stays blank. Power board all good. Cleaned flex tapes.

Board controller main IC heats up to ~70-75 celsius w/o heatpad, TCONs heat up to ~50 celsius. No other elements heat - confirmed using Flir thermal camera.

Is the display panel broken in your opinion? I can buy TCON board, Control board or whole monitor with broken display panel - as whole monitor is more expensive I want to ask - TCON, Control board or display?

Should i measure something? DMM, Oscilloscope available.

Best regards,

Coming with data - I've replaced TCON board and everything acts as it was - I've got another controller as well but it behaves exactly the same. Replaced PSU even the voltages were stable - nothing changed. I'm starting to belive that the matrix itself is broken but have no ideas how to troubleshoot it.

MAIN CONTROLER BOARD:

TCON BOARD:

MATRIX BOARDS:

I didn't attached matrix board thermal photos as nothing lights up. I've checked the voltages tho - there are WINBOND W25Q16JV flash IC's - they work on 3.3 V - on both matrix boards the voltage is present, stable and correct. Checked voltages on chokes - voltages seemed correct. +12V is stable. I tried to measure both matrix boards in form of comparison - results were mirrored so it seems there's nothing wrong on those boards.

Do you have any thoughts or hints what to measure or check? Maybe there is some way to debug/troubleshoot the matrix itself? There's an I2C on controller and MURA on TCON board but I think those are dead ends.

Br,

If the situation is the same your matrix is most likely [99% as all components work] broken.

Mine was.

この質問に回答する同じ問題があります

この質問は役に立ちましたか？

はいいいえ

スコア 0

5 件のコメント

@kundro post some pictures of your boards with your Question. That way we can see what you see. iFixitでの質問に画像を追加する方法

oldturkey03 さんによる2023年3月16日

@oldturkey03 I'll provide 4K pictures + thermal pictures tomorrow. Stupid I didn't think of that when I was in my workshop.

CRUDOfromBHM さんによる2023年3月16日

@kundro nah, not stupid. It happens and no worries :-)

oldturkey03 さんによる2023年3月16日

@oldturkey03 provided photos, br

CRUDOfromBHM さんによる2023年3月24日

@kundro so you've replaced the power supply, the main board, the t-con board and still no luck. the only board that you have now left should be the LCD controller board. Give us some good clean close-up on that. I am looking for voltage TP so the closer and clearer the better. Also, give us any number that might be a part number. That way we might find more info.

If you haven't replaced the power supply, do the same thing. Nice clean close up will help. Where did you measure your "stable 12V" voltages?

oldturkey03 さんによる2023年3月24日

コメントを追加

1 件の回答

@kundro post some pictures of your boards with your Question. That way we can see what you see. iFixitでの質問に画像を追加する方法 — oldturkey03
@oldturkey03 I'll provide 4K pictures + thermal pictures tomorrow. Stupid I didn't think of that when I was in my workshop. — CRUDOfromBHM
@kundro so you've replaced the power supply, the main board, the t-con board and still no luck. the only board that you have now left should be the LCD controller board. Give us some good clean close-up on that. I am looking for voltage TP so the closer and clearer the better. Also, give us any number that might be a part number. That way we might find more info.

If you haven't replaced the power supply, do the same thing. Nice clean close up will help. Where did you measure your "stable 12V" voltages? — oldturkey03

jayeff @jayeff 評価: 451.8千 11 367 1.4千 · Answer 1 · 2023-03-16T06:57:16-07:00

最も参考になった回答

jayeff @jayeff

評価: 451.8千

11

367

1.4千

投稿日: 2023年3月16日

オプション

Hi @kundro,

You said "...and act logical (turn on backlight to display manufacturer logo,..". Do you mean that the manufacturer's logo is being displayed on startup?

If so then there's nothing wrong with the screen.

If there's no video being displayed regardless of the input type but the logo is being displayed then there's a problem with the digital signal processing circuit on the mainboard.

The logo signal emanates from the software stored on the mainboard eeprom but then it uses the same circuitry to get to the screen via the tcon board as the video signal does after it has been processed by the DSP.

It could be faulty firmware but I can't find any online. You may have better luck

このアンサーは役に立ちましたか？

はいいいえ

スコア 2

4 件のコメント:

No. It acts logical because it turn on the backlight when turning on - every monitor displays manufacturer logo on the start - in that moment my backlight act like it should because it turns on for 2-3 seconds and turn off - in that moment status LED starts to blink which indicates sleep mode. In that way I'm sure that basic logic of the board works.

CRUDOfromBHM さんによる2023年3月16日

@kundro

I'm still not sure if the logo is being seen or not as to me your comment is not clear (the backlight is not the logo) but assuming that the "No" at the beginning of your comment above means that the logo is not being displayed, then it could be any one of the 3 components in the video path - mainboard, tcon board and screen.

As @oldturkey03 suggests providing pictures may be the next best step. Perhaps there are voltage references shown somewhere on the board

jayeff さんによる2023年3月17日

@jayeff As this was your only question your assumption is correct. I didn't had access to monitor today so I haven't made photos - I've ordered monitor with the same parts inside - the same parts was used by AOC, VIOTEK, Xiaomi, Gigabyte and Millenium - my monitor act exactly like in : https://www.reddit.com/r/Monitors/commen... - I'll try to replace the TCON board(as monitor works the same with/wo the TCON board) and get back with data.

CRUDOfromBHM さんによる2023年3月17日

Added photos as you asked. Jayeff - I think you saw this before in this thread:

Monitor shows blank screen. Backlight works..

CRUDOfromBHM さんによる2023年3月24日

コメントを追加

ディスプレイの

Monitor doesn't display but lights up.

Update (03/24/23)

Update (03/27/23)

1 件の回答

回答を追加する