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Krome88 Blank screen

 
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lkb225



Joined: 09 Jul 2013
Posts: 2

PostPosted: Tue Jul 09, 2013 12:32 am    Post subject: Krome88 Blank screen Reply with quote

This seems to be a hardware issue, but hoping it's something simple. When I turn on my Krome 88, the lights around the joystick come on and the blue light on the back of the keyboard comes on, but nothing else! The screen doesn't come on at all, none of the buttons light up, no sound...nothing. This happened all of a sudden. Was working perfectly, then I turned it on the other day and this. Anybody know what's going on? Or is it a job for the repair shop? Thanks!
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michobo



Joined: 21 Jun 2013
Posts: 17

PostPosted: Tue Jul 09, 2013 4:37 am    Post subject: Reply with quote

This is /maybe/ seriously malfunction. You must go to service for repair

Your last chance is to perform Initialization

Initialization
If your KROME should become unstable, you can
initialize it.
• Turn off the power, and then, while holding down
the EXIT button and PAGE button, turn the power
on.
The KROME will be initialized. While the data is
being loaded, the display will indicate “Now writing
into internal memory.”
The resulting state will be the same as when Load
Preload/Demo Data All is executed (see page 125).
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lkb225



Joined: 09 Jul 2013
Posts: 2

PostPosted: Tue Jul 09, 2013 12:34 pm    Post subject: Reply with quote

Yeah, I was afraid of that. I had already tried the initialization procedure a few times. Thanks. This sucks.
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rivanho



Joined: 14 May 2010
Posts: 36
Location: Ghent (Belgium)

PostPosted: Wed Jan 14, 2015 2:50 pm    Post subject: Reply with quote

Sadly I fear I have a similar problem.
When I swith the krome off to change SD card and then switch on again the screen remains completely black Sad I hear the beeps and it's starting up, I cam play it after startup but don’t see what I do.
When I wait 10-15 minutes it starts normally
So I will have to bring it in tot the service center Sad sad
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fearny



Joined: 06 Apr 2014
Posts: 6

PostPosted: Wed Jun 10, 2015 4:45 pm    Post subject: Reply with quote

Did you get to the bottom of it mine has started to be a black screen with lights tound joy stick on initial boot up from not being used for some time then i reboot its ok. My concern is that its my only keyboard i use live and if it goes down its a show stopper..
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pianobill55



Joined: 22 Feb 2015
Posts: 10
Location: Dunedin, New Zealand

PostPosted: Thu Jun 11, 2015 10:25 am    Post subject: blank screen Reply with quote

i made a post on a similar problem - turned out to be a condensor which the technician quckly repared. sometimes you need the expert help! Fantastic keyboard - off for a gig at the Portobello Hotel Dunedin New Zealand tomorrow!
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The Planz
Korg Krome replaced all the other keys
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sompat



Joined: 12 Jun 2015
Posts: 1
Location: HAT YAI SONGKLA THAILAND

PostPosted: Fri Jun 12, 2015 11:34 am    Post subject: I also get this display blank problem with my Krome88 Reply with quote

I also face this display blank problem.
I bought Korg Krome around 6 months ago via internet from some dealer in THAILAND.
At first, it worked perfectly until recently the display went blank.
I agree that it must be hardware problem but sadly I live in THAILAND and as far as I know there is none Korg service center nearby. I don't know what to do now, any suggestion?
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dfahrner
Platinum Member


Joined: 21 Jun 2008
Posts: 524
Location: Terrebonne, OR

PostPosted: Fri Jun 12, 2015 3:22 pm    Post subject: Re: blank screen Reply with quote

pianobill55 wrote:
i made a post on a similar problem - turned out to be a condensor which the technician quckly repared. sometimes you need the expert help! Fantastic keyboard - off for a gig at the Portobello Hotel Dunedin New Zealand tomorrow!


An electronics technician actually REPAIRED a failed board instead of just replacing it? I thought that no one could take the time to do that nowadays...and as my dad used to say about auto repair, "There aren't any mechanics anymore, only parts men..."

But seriously, pb55, can you give us any more information on the repair? Like which condenser (capacitor or cap) was replaced (that would be the component identifier "Cnnn" on the circuit board)? Was it a power supply bypass cap? Had the cap exploded or at least ruptured under internal pressure? More info might help someone else who has the blank screen problem...

df
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pianobill55



Joined: 22 Feb 2015
Posts: 10
Location: Dunedin, New Zealand

PostPosted: Mon Jun 15, 2015 2:32 am    Post subject: Reply with quote

Hi dfahrner

Grant told me that "The fault was a capacitor used for the reset of the LCD at turn on. " Its all a foreign language to me but I can say that there is great support from Korg here in NZ.

Smile
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The Planz
Korg Krome replaced all the other keys
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dfahrner
Platinum Member


Joined: 21 Jun 2008
Posts: 524
Location: Terrebonne, OR

PostPosted: Mon Jun 15, 2015 4:02 am    Post subject: Reply with quote

pianobill55 wrote:
Hi dfahrner

Grant told me that "The fault was a capacitor used for the reset of the LCD at turn on. " Its all a foreign language to me but I can say that there is great support from Korg here in NZ.

:)


Thanks for getting back to me, pb55, I realize that this is unfamiliar territory for non-electronic types...still, you might see if Grant remembers the capacitor's "ref deg" (reference designator, a number like "C125" that is silkscreened on the printed circuit board next to the capacitor, identifying the part), and/or the capacitor's value (in uF, that's "micro farads")...now you're going to start sounding like a real tech or engineer...

df
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juajo



Joined: 27 Jul 2015
Posts: 1
Location: argentina

PostPosted: Mon Jul 27, 2015 10:00 am    Post subject: Reply with quote

hola!!! soy de argentina!! tengo exactamente el mismo problema, mi krome se oscurece, este ultimo tiempo, muy seguido. me enamore de este teclado pero es muy triste no poder disfrutarlo al 100% si alguno tiene alguna data para solucionarlo seria de mucha ayuda ya que aca no hay servicio tecnico competente...
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wta



Joined: 07 Dec 2015
Posts: 4

PostPosted: Mon Dec 07, 2015 9:05 pm    Post subject: Blank screen fixed! Reply with quote

Hi all,

I've got this same issue of blank screen. I noticed that sometimes it would re-appear after a few hours/days, sometimes it would disappear again. I thought the LCD was dead. I ordered a new one on the net (almost any 7" 50-pin LCD with a resolution of 800x480 and about 15cm of cable will work). It cost me $15, it worked and failed again after one week.

Finally I disassembled the Krome again and observed the LCD power board, and found that the LCD reset pin (44) had a strange voltage of 1.5V instead of 3.3V. The reason is a design error in the choice of resistor R28. It's 10K while it should be 1K. With 10K it doesn't have enough strength to completely release the reset and it depends on the LCD's tolerance (which probably changes with aging).

I simply soldered a 1K resistor on top of it, verified that the voltage on the reset pin is now 3.3V, and the problem is now fixed.

In order to fix it, you must proceed like this :

1) put the Krome top-down on a soft surface like a bed. Take care of not putting too much strength on the joystick

2) remove all screws on the back. There are a lot, something like 37. Important : there's no hidden screw, so it's not needed to remove the rubber feet.

3) gently pull the back vertically, it will very easily come. If it doesn't, you forgot a screw.

4) you'll see the mainboard at the center, close to the back where the SD card is. You'll have to remove the screw with the plastic washer, and gently pull the soft plastified tin foil which protects against radio emissions I guess.

5) remove then all cables going to the motherboard (no need to confuse them later, though it's better to take a photo). In order to remove the flat ribbon at the bottom, you first need to pull the brown part of the connector outwards to unlock it (do not force, it will come by alternatively pulling each extremity with your nail).

6) remove the 6 screws from the motherboard, then take the motherboard out of the system.

7) remove the metal frame that supported the motherboard. 6 screws again IIRC.

8) you now see the small board with its cables like in this photo : .

It is not strictly necessary to remove the board to fix it but it's better as static electricity could destroy the LCD. The large flat cable at the top goes to the LCD. The small one on the top right is for the touch pad. The other small one at the bottom right goes to the audio board on the right. In order to remove the LCD cable, you first need to pull the white part of the connector upwards to unlock it (do not force, it will come by pulling with your nail). The other ones need to be pulled in their own direction without bending them.

9) remove the 2 screws holding the board, and slightly unscrew the 4 other ones holding the metal frame so that you can get about 2-3 mm of clearance. That will be enough to release the board from the 2 plastic tips which hold it.

10) find the resistor on the board. It's called R28 and marked "103" (10*10^3 ohms = 10K). There are two such resistors at the bottom left of the "CN17A" marking. The upper one is R29 and doesn't need to be touched. The bottom one is your friend. These two photos help locate it better :




11) DO NOT REMOVE IT! It's a small component, if you're not at ease with soldering small components, you'll certainly destroy the board by pulling off a copper lane. Instead, just find a 1 to 2k resistor on another unused board such as a dead motherboard. Such a resistor is marked 102 to 222. Note that the first two digits are less important than the 3rd one which is critical (exponent). It MUST in fact exactly be "10" to "22" followed by a "2". If you have something smaller than a 2 on the last digit, reset will never work. If you have something larger, your fix is useless.

12) Once you've found this new resistor, directly solder it on top of R28. If you're having trouble soldering something that small, first stick it on top of the other one using some superglue then put a very small part of solder on each side and that will be all. You must not heat it more than 1 or 2 seconds per side. The amount of tin to add is around 1mm * 1mm only.

13) verify with an ohm-meter that you have slightly below 1-2k when you measure across the previous 10k resistor. If so you did it fine.

14) reinstall the board, then tighten the metal frame's screws, screw the board, reconnect all connectors (be carefull with the small ones, you don't want to bend them or they could cut). Then pass the motherboard wires that you might have moved close to the board, reinstall the top metal frame, then the motherboard, reconnect all wires and power on. It must work. Once it's OK, you can finish to reassemble everything.

I noticed that black screws are used outside and grey ones are used inside, except a few holding the LCD frame and the keybed which are also black.

Try not to mark your screws. A screwdriver made for PC parts is perfect and will not mark. Count around 10-15 minutes just to disassemble everything, about as much to reassemble, and as much to fix the board once you have found a suitable resistor.

If you don't have a resistor, you can find one at an electronics components shop. Just go there with your board and they'll find the proper size. I guess it's a "0603" type of resistor (it indicates the size) though I'm not certain and forgot to measure.

I forgot to say, I noticed that the original Krome's LCD is of very good quality. When you replace it with a cheap one, images are really ugly. But that was better than nothing.

Hoping this helps other people!
--Willy
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caxton



Joined: 23 Mar 2011
Posts: 5
Location: Argentina

PostPosted: Wed Dec 30, 2015 4:25 pm    Post subject: Reply with quote

Hi, your investigation was excelent, this is the kind of trouble which can´t have a solution without the manufacturer´s help. But you did it alone!
Analizing the voltage in the reset point was a great move! Thank you!
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Bandman



Joined: 05 Feb 2016
Posts: 1
Location: Fresno

PostPosted: Fri Feb 05, 2016 4:04 am    Post subject: Reply with quote

Having same problem...no display and flickering lights at joystick upon power up. Anyone know how much a repair shop will charge to get it fixed. I'm not good with electronics. Thanks!
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NIO0850
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PostPosted: Tue Feb 09, 2016 2:09 pm    Post subject: Reply with quote

Wow shocked this is not recalled
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