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Repair a Tripp-Lite KVM (B004-DP2UA2-K)

morlata

Mar 22, 2023
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Mar 22, 2023
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I purchased this DisplayPort 1.2 KVM and it will work intermittently but will lose power within about 15 min of use and require all cables to be unplugged and plugged back in, and the cycle goes on and on... Tripp-Lite is replacing under warranty but they are recommending I recycle or throw out the defective device instead of sending it in, so instead of throwing it away I am attempting to repair to give to a friend. First thought is that it is a power delivery issue of some kind since all the functionality does work, up until power is seemingly lost. I noticed that there is an empty space for a Fuse (F2) on the top side which seems odd, although no fuse was loose in the case. There are also some empty spaces for resistors on the other side but I am not seeing anything else obviously wrong. Any ideas what could be wrong here? I was thinking of just running a wire across the empty fuse space but maybe that's a bad idea? lol
 

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Harald Kapp

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It is not uncommon tp have positions for parts that are not assembled. For various reasons, e.g. assembly variants or changes to improve the product during its lifetime. Do not assemble any of these components unless you know what theis purpose is. In your case: don't.

The effect you describe could be due to a thermal issue, i.e. componnets getting too hot with time. Does the effect persist when you operate the KVM with an open case (for better cooling)?
YOu should also visually check all solder joints for so called cold solder joints. Such a joint may give contact intermittently but fail due to mechanical or thermal stress. If you find such a joint, re-solder it using a tiny amount of new solder with a flux core or applying flux only. Do not create big solder blobs.

Also check this electrolytic capacitor:
1680242900550.png
Does it show signs of bulging or leackage? If you had a capacitance (or even better ESR) meter you could remove the capacitor from the PCB and measure its parameters.
 

morlata

Mar 22, 2023
2
Joined
Mar 22, 2023
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Thanks for the insight! I was hoping when I opened it up there would be a blown up capacitor honestly. The big capacitor appears pristine, although I don't have the correct tools for measuring capacitance. I did connect a multi-meter to it, on a high ohm setting, and watched as the resistance rose over time which an online guide said indicates it is holding a charge although granted not a precise measurement. I will see if I can get access to a better meter. I hadn't thought about the thermal aspect and cold-solder joints so I will check those.
 
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