Kronos X61 Won't Reboot (Temperature issue?)

traveler · Post by **traveler** » Tue Jun 23, 2015 2:26 pm

Hi all,

I've been having "not rebooting" issues with my Kronos X61 for a while but now I think I'm beginning to understand what is going on. Why I don't know, maybe you guys can help me...

The board will boot up 100% of times at the beginning of the day or gig. (So far).

The problem comes if the Kronos has been on for a while. If the system temperature is approaching 60 Celsius and I turn the unit off for any reason (or if it gets turned off by accident), then it WILL NOT boot up again for a while. Usually several neverending minutes, until it cools down a bit. When it finally boots up again and I check the temperature, it is always around 50 Celsius.

It goes like this. The unit starts booting up. The lights on the joystick turn on, the "disk" light under Set List turns on. The screen turns on for less than half a second. But then it immediately goes to black. And it all stops, like if it was never turned on.

Note: These summer days the starting temperature is around 50 Celsius. And after a little work, the unit will soon be around 63 Celsius. And stay there. The fan setting is on Auto.

I recently upgraded to OS 3.0.2, but I remember this issue of the reboot happening to me before. But every time it happened I freaked out so much that I switched different power cables frantically for several minutes until it boot up again. And I always assumed it was a cable problem, or maybe a contact problem.

I obviously need to take it to service, but I am in the middle of a heavy gigging season. Last time I took a Kronos under warranty to repair, I had to wait for it for a month. The board is still under warranty btw.

I'm lost here. Don't know how to go about this.

Any suggestions would be more than greatly appreciated,

T.

Rigel · Post by **Rigel** » Tue Jun 23, 2015 3:34 pm

Many Kronos owners here reported that theirs works around 60-65 degrees Celsius and sometimes even hotter, so I guess autoshutdown due to overheating is not the issue here, though we cannot rule out the possibility of heating cooling loops causing momentary disconnection of something. You should also check the mains power supply for power surges or microsecond voltage reductions, against which Kronos is known to be highly susceptible. Try using a UPS while gigging before sending your synth for repair.

AntonySharmman · Post by **AntonySharmman** » Tue Jun 23, 2015 3:58 pm

traveler wrote:It goes like this. The unit starts booting up. The lights on the joystick turn on, the "disk" light under Set List turns on. The screen turns on for less than half a second. But then it immediately goes to black. And it all stops, like if it was never turned on.

If your Kronos power is turned off abruptly while booting and joystick led goes blank then your issue might be the PSU (not rare at all !).
Also note that this CPU can work fine up to 85 degrees of Celcius !

traveler · Post by **traveler** » Tue Jun 23, 2015 4:39 pm

Thanks for your replies!

For what is worth, this is happening at my home studio, where the Kronos is connected to a Furman Power Plus Series II conditioner.

The issue is not that the unit is rebooting by itself. The Kronos will not turn itself off. At least not yet.

The issue is that IF I turned it off AND if the system temperature is more than 59 Celsius, then booting up will abort almost instantly.

I did some testing yesterday. If I turned off the unit at 50 degrees Celsius and turned it back on, it booted up without a problem. Same at 52, 55 and up to 57. At 58 it becomes a toss up. Sometimes it works, sometimes it doesn't.

If it remains on it will work for hours without any problems yet. The temperature remains stable around 65.

It is like a car engine that will not start when hot. But if it cools down, then it will start up and run without a problem.

I am getting a UPS for outside gigs regardless. But I think there might be some other problem here.

Thanks!

T.

branman · Post by **branman** » Tue Jun 23, 2015 5:24 pm

Keep in mind, that as soon as the unit is off, the fan stops spinning of course, so heat that is present in the cpu will not be dissipated. This is similar to turbo chargers in car engines that overheat and fail after the ignition is turned off. The temperature reading you get is when it's powered up and the fan is running. It's likely to be higher with the fan stopped despite the cpu not drawing current.

traveler · Post by **traveler** » Tue Jun 23, 2015 5:33 pm

Thanks Branman.

So let's assume the temperature is 70 Celsius or maybe 75 instead of 60 once the unit is off.

I guess at that point the temperature sensor inside the Kronos is telling the system that it is not safe to boot up at that temperature.

Have you ever had a similar issue? Is this the standard then or is the sensor in my unit overdoing it?

At this point in summer, it is happening to me every time I use the unit for more than 5 minutes and turn it off for whatever reason.

T.

AntonySharmman · Post by **AntonySharmman** » Tue Jun 23, 2015 5:40 pm

- Note that when I say PSU I mean Kronos switching mode power supply (Enhance)

- CPU isn't the only part that can be overheated , and you monitor only CPU !

- When CPU is overheated , motherboard turns off this PSU at any time not at booting time.

- When Kronos turns completely off while booting then two things can cause that
1) ENO Enhance PSU module that will soon completely fail by 95 %
2) Partial motherboard switching malfunction by 5 %

traveler · Post by **traveler** » Tue Jun 23, 2015 6:43 pm

Thanks Antony,

So I am probably looking at a ENO Enhance PSU replacement or motherboard replacement...

I will take it to express repair in the city tomorrow. And will let you know what they say. But I cannot leave there past Thursday, so I will have my fingers crossed.

The unit has never turned itself off yet. Even after many hours of working. I am not going to test that though, cause I fear it could overheat.

T.

AntonySharmman · Post by **AntonySharmman** » Tue Jun 23, 2015 6:51 pm

My experience says ... your Kronos won't fail because of temperature , so leave it turned on before your gigs begin !

Good luck

krkan · Post by **krkan** » Thu Aug 29, 2019 7:01 am

Hi,

i know this is 4 years old topic, but i have the same problem like traveler with my Kronos X88. It does not want to reboot if the system temperature is 59°C or higher. On 58°C (or lower) Kronos makes reboot without any problem.
Is this some kind of protection or what?
Reboot=power outage simulation

Here is the video
https://www.youtube.com/watch?v=9Uf6xTCdTdA

AntonySharmman · Post by **AntonySharmman** » Thu Aug 29, 2019 9:47 am

Maybe you're very close to Kronos PSU complete failure ...
59°C for CPU core is a very normal temperature and normally motherboard ST-BY output pin for PSU is not enabled via CPU protection circuity at this lower level temperature ...
It needs further investigation , maybe PSU is overheated at current time.

krkan · Post by **krkan** » Fri Aug 30, 2019 8:01 am

Hi Antony and thanks for your reply.

I'm not so sure that you're right.
First time i have seen this "reboot" problem on my Kronos about 4 years ago. It was very hot on stage and then during the koncert...power outage. In next two minutes we have the electricity again, but Kronos wants boot about next 10 minutes.
If there PSU problem it means that complete PSU failure should have happened a long time ago. I must say that i did not have any problem or system failure with this engine in last four (and more) years.

We have again power outage on koncert two weeks ago...and again same problem...about 5 minutes it wants boot. This is actually the reason why i want to check what's really going on.

Yesterday i checked PSU. It is not overheated after 2 hours of work (normal operating temperature). Also i applied new cooling cpu paste on processor. Now i have system temperature constantly about 60-62°C (room temerature was about 26°C), but if i turn it off and again turn on....this stupid thing wants boot until the system (or CPU...i don't know) temperature drops to 58°C or less.

It must be something (maybe some kind of CPU protection) with this 59-60°C "magic border" because traveler wrote hier about same problem with same temperature values.
Coincidence? I don't think so.

If somebody has Kronos X: Please try to restart your Kronos when the system temperature is more then 59°C and tell me if you have same problem. THANK YOU!!!

Next step: maybe something like this
http://www.korgforums.com/forum/phpBB2/ ... p?t=100141

AntonySharmman · Post by **AntonySharmman** » Fri Aug 30, 2019 11:03 am

Since you have opened your Kronos then try to find motherboard output control pin that goes to Enhance PSU (its the green cable if I recall right).
This control 5V voltage output should be at Low state in order PSU to enable all the rest power outputs of PSU , if motherboard is responsible
for this via CPU temperature protection logic then this output will be at high 5V state when you power on your Kronos and still no power is feeding mobo.
In any other case , PSU is causing that either not providing ST-BY 5V to mobo , nor above enable input stage is malfunctioning ...

My Kronos X had the same issue before 4 years , then one day did not started at all ... Enhance ENO was replaced.
Now it oparates with disabled fan (for noise disturbing reason) at 65°C.
According to my WavesArt service support center , by 95% PSU is the cause of this boot delay or not booting later at all !

Hope this helps

krkan · Post by **krkan** » Fri Aug 30, 2019 1:29 pm

Thank you Antony!

I did the following: i mounted this small Fan on the CPU cooler

...and here is the result after 4 hours playing on my Kronos. The temperature goes maximum to 46°C if i play "heavy" sounds and combinations, but it goes also down on 44°C if i don't play. The temperature in my little studio is in this moment about 28°C.

and Kronos reboots without any problem.

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Kronos X61 Won't Reboot (Temperature issue?)

Kronos X61 Won't Reboot (Temperature issue?)

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