Keywords： Only One display is working | Display not working | One monitor working only
Applicable product models: Dual Monitor KVM; Triple Monitor KVM
HKS0402A1U/HDK0402A10/HKS0202A2U/HKS0402A2U/HKV0402A1U/HKS0802A1U/PKS0802A10/HKS0403A1U etc.
All possible factors for a black screen on a Dual/Triple monitor KVM switch
For situations where all monitors show a black screen, we have provided possible troubleshooting issues below. Please refer to the following suggestions for assistance, 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 ready to help and provide after-sales support.
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Input and output issues, docking station compatibility, and cable problems:
Please try connecting the problematic monitor directly to the computer (bypassing the KVM) and check if the issue persists. If the monitor still doesn't work, 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.
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Docking station/adapter issues:
Have you used any adapters or docking stations to connect the computer and monitors to the KVM switch? If so, check the signal direction of the adapters or try using a different adapter. The correct signal transfer direction is from the computer to the KVM switch and then to the monitor. For example, if the input source port is USB-C and the KVM port is HDMI, the appropriate converter to use is USB-C to HDMI, not HDMI to USB-C.(If all external monitors can display normally when directly connected (bypassing the KVM switch), please proceed to the next troubleshooting step.)
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Resolution of the monitor:
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Computer output capabilities are limited. It is recommended that you refer to your computer's official website to check the specifications. For example, some older PCs may not support outputting two 4K 60Hz video signals simultaneously, but they should be able to handle two 1080p signals without issue. In this case, lowering the resolution usually solves the problem.
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The EDID reading is abnormal. It means that the video signal being output exceeds the recommended resolution and refresh rate. This usually happens when the monitor's optimal resolution refresh rate is higher than the KVM's optimal resolution refresh rate. "To confirm this problem, you can judge by comparing the output parameters of the expansion screen when connecting directly and through KVM; or through professional EDID reading software to confirm(you can consult customer service to get it). In some cases, the problem can be solved by hot-plugging the input cable on the PC side or restarting KVM".
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The actual output video signal bandwidth exceeds the maximum bandwidth supported by the intermediate device. It will happen when the input source device and the monitor support the G/F-Sync function at the same time. Please try to turn off the HDR10, G-Sync, and FreeSync of the device.
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Cable issues, like length or quality
The cable exceeds the specified length, or the quality is not good, which may cause a flickering screen. Please try to change to better quality cable. Check if the length of the HDMI/DP cable meets the specifications below. Because the corresponding cable length will directly affect the output resolution.
Our KVM is equipped with a 1.5m 4k@60hz HDMI input cable.
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When using 4K@60Hz as the input source, the output HDMI cable should be less than 5 meters.
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When using 4K@30Hz as the input source, the HDMI cable at the output end should be less than 10 meters.
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When using 1080@60Hz as the input source, the output HDMI cable should be less than 15 meters.
For the DP cable, it is recommended not to exceed 1.8 meters.
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Check for monitor recognition issues:
If the computer recognizes the name of the KVM instead of the name of the monitor, the output port of the product may be abnormal. If the computer does not recognize any name, the input port of the product may be damaged. （Does not include PKS0802A10）
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Final cross-experimentation method:
The aim is to determine the root cause of the issue, whether it is with the computer's output port, the connection cable, or the KVM switch port.
Question 1
Dual/Triple Monitor KVM Switch Only one monitor can display
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If you have at least 1 video connection from each computer then using the Mode 2 feature (each computer on each monitor) you can test the KVMs output to the monitors. Both displays should work when Mode 2 is active. This confirms the KVM output is working fine. Further investigation is needed to determine whether the issue lies with the KVM input port or the input cables.
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If you have only one monitor working, it's likely that you're missing the second video connection or the dock/adapter you're using is incompatible. Even if the adapter works when not connecting it to the KVM, it is possible that the adapter does not work well in the KVM environment.
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Firstly, Please try connecting the black-screen 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.
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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. For detailed crossover experiments, please jump to this link.
Question 2
Dual/Triple monitor KVM switch at least one input source can be displayed properly.
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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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