Replacining Internal Power Supply PCB on Korg Kronos X

[average_male]

Ok, and I think you already confirmed this, but looking the ATX connectors, all of the pins are properly seated such that they are visible and flush and they don't get pushed in when slight pressure is applied to them, right? All pins should be visible and flush as in this picture (none should be like the 3rd one on the bottom as noted in this picture):

https://i.ytimg.com/vi/Sm2Nsz-xJ7o/maxresdefault.jpg

[BlackForest]

OK, I'll try to explain once more : I am not using the pins as such. I took these ones out, soldered the cables from the new PSU (I cut off their pins) on them, and pushed them back into this sleeve. So there is no issue of properly seating anything. I did check these soldering for proper conductance.

[average_male]

OK, I'll try to explain once more : I am not using the pins as such. I took these ones out, soldered the cables from the new PSU (I cut off their pins) on them, and pushed them back into this sleeve. So there is no issue of properly seating anything. I did check these soldering for proper conductance.

Oh, totally sorry about that. I thought when you stated you changed the connector end and not the PSU end, I took that to mean you created and crimped the new connectors. Again sorry. That's even more perplexing now (and wondering how you reconnected the original PSU, unsoldered all wires...).

By chance you have another motherboard that takes the same connector as the Kronos' motherboard? The new PSU is the last thing to confirm working as expected. For all we know, the power supply was bad from the start or during splicing, soldering and testing it got shorted and cannot support the expected load anymore.

Just grasping and theorizing at this point as there isn't much for me to go on given my position/location.

[BlackForest]

No probs averagemale... I appreciate all the help. And yes, it is difficult to explain what has been done and what not.
I don't have any other MB to test.
So for now, hm, I might be putting it back together and let it run for quite some time to see if the sounds - for some reason - stopped cutting out, and if the Kronos can be restarted immediately, repeatedly. These were the issues why I wanted to swap it initially.

[average_male]

Cool, I admire your determination and braveness to attempt this PSU upgrade. And the work you are doing will help others planning/needing to upgrade their PSU as I would imagine Korg (and its supplier) may not be producing the stock PSU in the near future and any failing PSUs would need replacing. Will keep an eye out for any updates/progress. Thanks.

[KK]

You could also test your new PS by itself to see its behaviour. There might have been some mistake connecting it or as previously mentioned there could have been some overload created as the original PS has stronger specs for the -12 V, etc. If the new PS behaves normally with minimal load, that could explain the issue. Following the same example, I would then personally measure the current drawn for the -12 V with your original PS to confirm, etc. Of course, no need to do anything of this if your Kronos now works fine.

[BlackForest]

The Kronos has been running now for 2h with the old PSU OK.

Now while the sound cutting off happened very unregularly and so I can't confirm this yet, what on the other hand is new: I can restart it again straight after switching it off, no matter how long it ran! So an improvement even though I didn't really change anything..
Only what's popping up now is a low Bios battery...

[average_male]

Given this new behavior, original issue may have been a loose connection of some sort, right? But glad to hear things appear to be working better now.

[projectaspen]

Hi,

sorry to crash the subject again

after it went to Korg official repairshop and back working for some months, the Kronos X is failing again (needs to power on twice to start).

I read the threads and the adapter seems a bit too much for me to do, I have a heavy hand. Can't I just use a standard caseless 20 pin PSU to replace?

like this perhaps? https://pt.aliexpress.com/item/1005006270836966.html

I am also a bit worried about that motherboard 5v starter thing, does that need to be connected to PSU too?

[BlackForest]

You might have seen my experience with trying to replace the PSU, which ended in such a way that I put the old one back in again. But since that time it works! Strange. So I suppose in my case it was only necessary to reaseat the cabling that comes out of the PSU. Give this a try.

Do you know what Korg did with your board at all?

[BlackForest]

little update... My Kronos X is switching off by itself again...so it was only a temporary fix (which I feared it would be anyway).

Hence my new post about a list of working alternative PSU...
Back to square 1.

[BlackForest]

So, just in case someone is bored and reading this. I had to pick up this thread as my Kronos X is coming down with the same issues (sudden power outage, and then difficulties restarting it).

I have tried to replace the PSU with another model, this one, which doesn't seem to require a minimum load (so-called no load protection NLP).

https://www.fsplifestyle.com/en/product ... u300w.html

It still won't work though.

I could imagine it does matter which (for example) orange cable you're using where. Like a +3.3V sensing cable must go into the right header. I am not sure as I didn't look out for this: The PSU I got had only black wires.. So I had to figure out which is which and I cut it's header off and connected the cables with luster terminals temporarily to short pieces of coloured cable.

And yes, I did double check their voltages.
Am afraid I didn't take any pics, am always too focused on fixing the issue...

But as said, I didn't check if I used the "correct" (again example) orange cable on its one-to-one counter part, I might have mixed up within each colour group.

Any experience on your side with regards to this?

There was no brown cable on this PSU but AFAIR a doubled-up orange and also black cable. I might go back and try to find the exact allocation of each cable and pin.

This MUST be solved.

In the mean time I had put back in the original PSU and so far it is still working (thank goodnees I haven't made it worse with all my tinkering), however I didn't have the time yet to really test it and let it get warm.

On a side note, I opened the original PSU up completely to have a look at the soldering of each component and they looked fine to my untrained eye.
What I DID do though is add some heat paste on 4 ICs (I suppose that's what it was). The are at the bottom and can only be seen when you take the metal case completely off. They have indirect contact with the metal case with a silicone heat transfer plate/layer, max. 1 x 1 " . It is over 10 years old and one can see the imprint of the 4 ICs, so I thought I might upgrade it with some ceramic paste. Also because my issues mostly happen when the Kronos had been running for a while, say 1 hour.

I'll keep you posted if it happens again, now that this heat paste is a new change. Maybe this is an issue for some of us?

[Sweat]

I appreciate those that attempt replacing the motherboard or power supply. Although as a friendly reminder, trying a few other things first is recommended.
Searching the forum, you see many have issues with their Kronos randomly shutting down or not starting up. It seems most likely to indicate a power failure.

I found this post that appears to be a service bulletin from Korg to help qualified service techs with this. Since it is interesting that data on the SSD can become corrupt and also cause this problem, bulleton item #5 mentions reinstalling the DVD.
https://www.facebook.com/groups/1970799 ... 897049930/

[BlackForest]

....

I'll keep you posted if it happens again, now that this heat paste is a new change. Maybe this is an issue for some of us?

So far no further issue with switching off by itself. Keeping in mind, it's not quite 30°C in Germany anymore...

[BlackForest]

Cool, I admire your determination and braveness to attempt this PSU upgrade. And the work you are doing will help others planning/needing to upgrade their PSU as I would imagine Korg (and its supplier) may not be producing the stock PSU in the near future and any failing PSUs would need replacing. Will keep an eye out for any updates/progress. Thanks.

@average_male, I am still not at peace about the colour mix in your initial thread. I will try to upload a picture, not sure if that works.
Alternatively referring to your post:

http://www.korgforums.com/forum/phpbb2/ ... p?t=121491

What it shows is your wiring, especially the 4pin cable with original purple, black, green, grey (in that order). These you connected to red, probably black, green and white/grey.

How can this be? The purple black green grey is a set combination, and the colours are standardized. So, how made you to connect red to purple?
I cannot get my head around it...especially that my second try with a different PSU also doesn't work.
I don't need so many lab PSUs standing around