Dual/Triple Monitor KVM Switch Only one monitor can display

Keywords: Display; Blackout; Monitor; KVM switch; One black screen

Applicable product models: Dual Monitor KVM; Triple Monitor KVM

HKS0402A1U/HDK0402A10/HKS0202A2U/HKS0402A2U/HKV0402A1U/HKS0802A1U/PKS0802A10/HKS0403A1U etc.

If you are experiencing a problem that one of the external monitors connected to the TESmart KVM switch displays a black screen, please try the following troubleshooting steps. If the issue persists, please reach out to the TESmart Customer Service Center for further assistance. You can contact us through the chat window at the lower right or by submitting feedback. Our dedicated team of professionals is always ready to help and provide after-sales support.

To troubleshoot the issue of a black screen on one monitor, please follow the steps below. The goal is to determine if the problem lies with the output port on the computer, the output port on the monitor, the cable, or the KVM switch port.

📌Firstly, how can we determine whether the issue lies with any input/output port, cable, or docking station?

Please try connecting the black-screen monitor monitor directly to the computer (bypassing the KVM) and check if the issue persists. If the monitor still has no image, it suggests that the problem may lie with the source, monitor, cable, or docking station. It's important to keep the original cable or connected converter unchanged during this testing process.

Direct Connection Test.JPEG

📌Secondly, how to determine whether the issue lies with the part connecting to the KVM including KVM ports, and input/output cables? Please take the following cross-experimentation methods to troubleshoot specific problems.

  1. If all input sources have a black screen on the same monitor.

First, above all, please make sure all the cables have been connected properly to the KVM

HDMI+DP.JPEG

The purpose of following troubleshooting operations is to find out whether the problem lies with the Output connection part, including the output port on the KVM switch and the output cable.

  • STEP1——Please exchange connection ports which the monitors connected to the KVM ONLY

(keep the location of the monitor and cables unchanged )

🎯Cross testing is shown in the figure. (The product model in the picture is HKS0402A1U as an example)

Before: Assume that before the crossover experiment, Monitor1 shows a black monitor and Monitor2 is a working monitor.

Monitor1 ---> Display1 output ---> (black screen)

Monitor2--->Display2 output---> (working monitor)

Exchange the connect port only.JPEG

Result①:

Monitor1 -->Display2 output-->(Black monitor)

Monitor2-->Display1 output-->(The working monitor )

 

Result:

Monitor 1 continues to display a black screen, while Monitor 2 remains functional. This suggests that the issue is not related to the KVM port, but further confirmation is needed.

Result②:

Monitor1 -->Display2 output-->(The working monitor)

Monitor2-->Display1 output-->(Black monitor )

 

Result:

If monitor 1 returns to normal display and monitor 2 goes black, there may be a problem with the KVM port. Please contact us via the chat window on the bottom right or submit feedback for further assistance.

  • STEP2——keep the connection status completed in STEP 1. Please exchange the cables connecting the display and the KVM

(Keep the monitor and KVM output ports unchanged )

🎯Cross testing as shown in the figure.

Before: Assuming that before conducting the cross-experiment, Monitor1 shows a black monitor, Monitor2 is the working monitor.

Monitor1---> Display1 output--->(Black monitor)

Monitor2--->Display2 output---> (The working monitor )

Exchange the cables only.jpg

Result①:

Monitor1 -->Display2 output-->(Black monitor)

Monitor2-->Display1 output-->(The working monitor )

 

Result:

Monitor 1 continues to display a black screen, while Monitor 2 remains functional. Please contact us via the chat window on the bottom right or submit feedback for further assistance.

Result②:

Monitor1 -->Display2 output-->(The working monitor)

Monitor2-->Display1 output-->(Black monitor )

 

Result:

If monitor 1 returns to normal display and monitor 2 goes black, there may be a problem with the HDMI cable. We recommend replacing the HDMI cable connected to Monitor2 to fix the issue.

For the situation where the monitor screen is black, please help me perform the following troubleshooting tests. The purpose is to find out whether the problem occurs with the KVM switch input port or input cable.

  1. If All input sources have a display with a black screen, but it is not the same display.

(Confirm that in dual-screen mode, input A corresponds to Display 1, and input b corresponds to Display 2)

  • STEP1——Please exchange the position of the KVM port where the input source is connected,

(Keep the computer and cables unchanged.)

🎯Cross testing as shown in the figure.

Before: Assuming that before conducting the cross-experiment, Monitor1 shows a black monitor, Monitor2 is the working monitor.

PC1---> PC1 input--->(Black monitor)

PC2--->PC2 input---> (The working monitor)

Exchange the connection port on switch only.jpg

Result①:

PC1-->PC2 input-->(Black monitor)

PC2-->PC1 input-->(The working monitor)


Result:

The PC2 port, which was previously displaying normally, followed the connection of Computer 1 and caused the PC2 port to turn black. However, the PC1 port becomes normal and resumes operation. This confirms that the KVM switch input port is functioning properly. However, the cause of the problem might be the audio and video cables connected to Computer 1 or its output port. Therefore, further investigation is necessary.

Result②:

PC1-->PC2 input-->(The working monitor)

PC2-->PC1 input-->(Black monitor)

Result:

The previously functional PC1 port is now not displaying, while the PC2 port is still working correctly. This indicates that the PC1 input port on the KVM is faulty. Please reach out to us via the chat window at the bottom right or by submitting feedback for further assistance. Our team is available to help you troubleshoot the issue.

  • STEP2—— maintain the connection state completed in STEP 1. Please exchange the input cable connecting the computer to the KVM,

(Keep the computer and KVM input ports unchanged.)

🎯Cross testing as shown in the figure.

Before: Assuming that before conducting the cross-experiment, Monitor1 shows a black monitor, Monitor2 is the working monitor.

PC1---> PC1 input--->(Black monitor)

PC2--->PC2 output---> (The working monitor )

Exchange the cables only-2.jpg

Result①:

PC1-->PC2 input-->(Black monitor)

PC2-->PC1 input-->(The working monitor)

 

Result:

The PC1 port, which was previously functioning normally, is still working fine, while the PC2 port is not displaying anything. Please contact us through the chat window at the bottom right or submit feedback for further assistance. Our team is ready to help you troubleshoot the issue.

Result①:

PC1-->PC2 input-->(The working monitor)

PC2-->PC1 input-->(Black monitor)


Result:

The black screen issue on PC1 has been resolved and it now displays normally. However, PC2, which was previously working fine, now has a black screen. This indicates a potential cable problem with PC2. We recommend replacing the HDMI cable connected to PC2 to fix the issue.

Dual/Triple monitor KVM switch at least one input source can be displayed properly.

  1. If PC 1 works well with both monitors but PC 2 does not then you can swap PC 1 over PC 2 Inputs. If PC 1 works fine on both inputs, this confirms the KVM is working fine and the issue is related to PC 2. Could be the port, adapter, or dock being used.
For detailed crossover experiments, please jump to this link.

All the above steps are designed to troubleshoot the real problem that affects your normal use of the product. If you have confirmed the problem after certain testing steps, please contact the TESmart Customer Service Team through online chat or email and explain the troubleshooting you have done. Then they will help you solve the problem ASAP.
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