Aten Slideaway KVM power supply repair

[hanakp]

I thought this would be another straightforward repair, but I was in for a surprise, so I'm mentioning it here.

We have several Aten Slideaway CL5808N KVMs in my workplace and one of them stopped working. Interestingly, the LCD monitor displayed a logo upon powerup, but the rest (keyboard and KVM itself) was completely dead. That happened because the LCD is powered from 12 V supply, but the rest from 5 V supply. There is only one 12 V SMPS in the unit (Mean Well RPS-60-12) and the 5 V rail is derived by a step-down converter on a small separate PCB. The converter was dead and apparently it's not available as a spare part (it has part number KL1516-AAX-32 on the underside). I feared the faulty converter may have damaged the rest of the KVM, but luckily it worked normally when I powered it from a benchtop 5 V supply.

I haven't even tried to repair the converter board, I have poor track record with such power electronics - when I replace one component, another usually fails within a few months. The question was, how to replace the board and here I run into difficulties. The KVM normally pulls about 0.7 A from the 5 V rail, so I thought 2-ampere 78xx drop-in converter Recom R-78B5.0-2.0 would be fine. Well, it wasn't, the KVM rapidly restarted itself and its beeper produced odd chirping sound. I assumed it's because the KVM has large inrush current, so I used 5-amp Bel Power SRBA-06E2ALG module next. That worked fine, but I had to insulate the entire module so it wouldn't short-circuit with KVM case or someting else. When I covered it with shrink tubing, its temperature quickly rose to 90 deg. C - it was obvious it wouldn't last very long. Finally, I tried another 78xx drop-in converter, this time 3-amp Gaptec LC78_05-3.0. With that one, the KVM finally works and the converter runs at only about 40 deg. C. The rest should be obvious from the photos, it's ugly, but works. BTW, don't get fooled by the wires, their colors don't reflect the voltages nor their polarity.

[btjtaylor]

Thank you very much for making this post, I have an Altusen (I believe Aten is the same company) KL9116 slide-out KVM that I use for occasional troubleshooting etc of some rack mounted servers I have at home for learning/project purposes,

I got the device for free from an old workplace years ago and recently it died in the same way as yours - the LCD powers up but the KVM itself is dead.

I briefly opened it and everything looked to be in OK condition internally (I was hoping to see something obviously burned out). On my multimeter is was finding 12v all over the boards inside so I put it to one side.  I didn't want to spend a lot of money on a replacement unit (they are surprisingly expensive second hand, normally this kind of stuff is almost worthless, and I didnt want to go for a different brand as I would've had to buy a whole new set of cables etc) so figured i'd return to it at some point.

That day came and I had another search on google today and found your post and checked and I am also not finding 5v anywhere inside so it looks to be the same problem - based on your photos I have the same board inside too - I will order the Gaptec component you mentioned and fingers crossed it will mean a successful repair,

Is your repair still working OK? 

[btjtaylor]

I had a look for the component you mentioned but I couldnt find one locally and I didn't really want to spend €12 on shipping a small component so I ordered a very cheap PCB from ebay with the closest specs I could find - "MP2307 12V to 5V 3A DC-DC Step-Down Power Converter Module/Charger" (https://www.ebay.co.uk/itm/325318890675?var=514216054465)

It arrived this morning and I quickly installed it into the device. I had to spend a bit of time missing with the pot on the board to adjust the voltage as out of the box it was reading around 9.5v, but managed to get it so it read 5.12v which is close enough. I wired it up basically as per your photos - I was able to secure it down in place of the existing board with only a single screw which is not ideal but it'll do the job



And the moment of truth.... success!