Switch Dockingstation no HDMI output on TV

Hi, i have 2 docks which do not output a signal to the TV, but when i plug in a Switch it gets charged.
The Switch is not the Problem because it works fine in a known good dock. I also tried it with different switches. Do you know which chip is responsible for the video output in the doch ?

Thanks in advance.

I had a switch with same problem. I replace the usb connector from another broken dock and it worked.

It was same symptom, dock n charges but no video. Solid green light on dock.

Hope it helps

Hi, i already swapped the mainboard into a knowm good dock to rule out the USB C and it still did not work. It must be a fault on the Board itself.

This may sound stupid, BUT…

What order did you plug in the AC adapter & HDMI? Apparently there is a specific order. AC adapter first and to a wall outlet. Then the HDMI to the dock, and then to the TV.

I was having the exact same issue and this solved it. No problems since then.

Hi, i already tried that too, but still no signal.
I think the M92t17 HDMI IC Chip is dead but i dont know how to check it.

that problem is usually caused by audio/video controller chip PI3USB on the back of the board… you have to replace it…

like i sayed above i tested with two differnt known good Switches and neither showed a picture with the bad dock. When i take my known good dock everything works like it should. So the switch is not at fault. It must be a fault on the dock mainboard.

Sorry. It was a direct reply to La_Hache_Es_Muda and I missed it is going off topic.

Maybe this could help a bit to locate the problem. I would check the yellow marked filters to the hidden HDMI converter at HDMI Port:

testpoints in diode mode

1 392
2 0 GND
3 445
4 444
5 437
6 437
7 425
8 449
9 431
10 437
11 0 GND
12 465
13 463
14 0 GND
15 692
16 513
17 446
18 719 NRST
19 700 SWDIO
20 0 GND
21 700 SWCLK
22 406 V_LDO33
23 426
24 510

1 584
2 648
3 620
4 641
5 645
6 651
7 651
8 698
9 665
10 654
11 570
12 566
13 494
14 448
15 335
16 335
17 525
18 693
19 567
20 386
21 407

1 681
2 606
3 480
4 515
5 320
6 571
7 534
8 571

1 604
2 286
3 231
4 498
5 286
6 606
7 286
8 231
9 480
10 551
11 OL
12 450

1 438
2 0 GND
3 438
4 438
5 428
6 0
7 436
8 521

Hi, most of the points i tested did not give me a reading and when it did it was only half or double the value you wrote down. While i tested i noticed that the marked (light blue)“caps?” were shorted to ground on both sides. Is that normal?
I also checked the Filters. They have continuity.
When you need the proper values i can write them down.

I measured different boards a few times and I m allways getting this values at all test points plus minus ~20 mV. I also compare my values with an other multimeter and got nearly the same readings.

Did you put the red probe on ground and measure with the black probe at the testpoints?

The blue marked components have ground on both side.

I now have a second dock with no output to tv. Both have at the testpads blue 6 and 8 “oL”. Did anyone knows where this lines goes to? And is the VLI ic exchangeable?

Calvin. I believe all the working board i had , have 0L reading( lot of 10 i was fixing) the bad ones have a reading on test pad 6 and 8.

I had a couple that shorted the yellow pad 13, replace with the big chip next to it and it works.

The others were the chip on the other side of the board. Theres two testpad there that suppose to have 0.001 reading or so, if its bad it has some other reading like 0.5 in diode

If i remember correctly, i replace two of those VLI chip on the board and it didnt change anything

I can confirm that Blue 6 and 8 are OL, I just repaired one today.

My symptoms were red 4 was shorting or close to shorting. replace m92t17

I measured a known good working dock again and you are right with OL at blue pin 6 and 8. I tested all testpads again and the pins at the big ics (m92t15/m92t17/VLI/ST) on the defect board but nothing obvious like a short or OL.

I have the opposite problem. 3 boards with a reading on testpad 6 and 8, probably gonna start removing ICs to see which one clears it. I see its its runs to the VLI ic but replacing that IC does not change the value for me so it has to be another crossover somewhere

I guess theirs variations of boards,

Got a board that does have the 0.7 reading on that point 6 and 8 and is working fine. Tested for couple hours with no issues

Can someone help?
I have a short circuit to GDN on green pin 12.
What could this be causing?
The others have the correct values