Who is going to take their Krome apart to peek under hood?

[maranite]

...found sd card extension cables here:
http://www.ebay.co.uk/sch/i.html?_sacat ... sion+cable

Will order one, fit it, and let y'all know how it goes.

[Kromeheaven]

BTW... I imagine the it would serve us well to figure out a mod that allowed the internal sd card socket to be accessible from the back panel.... I.e. wire out to a case-mounted slot.

Once we've figured out what's going on with the sd card, Cyph would probably be able to mod his sample conversion software to write entire new 4gb PCM ROMS for the Krome.

This would be a game changer for Krome owners... the ability to completely customize the sample set, and not be stuck with just one well-sampled piano.

Who's got the skills to figure out how to make such a mod?

Yes, it would be my new challenge if only I had a dump of this sdcard !

I do not have skills in electronic mod, but I can help in software understanding...

In fact, I don't know if the content is :
1) Original Samples
2) Operating system

Both are interesting...For sure.

[maranite]

I got too excited to wait, so cracked my Krome and am busy backing up the sdcard right now.

Headline:
Its a class 10 4gb "O2Micro" micro sd card, single partition, which windows recognizes as a "raw" file system.

This answers the earlier question about "how did korg jump from 50mb rom to 3.8gb".... they used commodity storage.

I'm speculating that the motherboard boots the arm processor with a U-boot bootloader, which in turn loads the main program into ram and passes control to it. The main program then loads the remainder of the sdcard (the sample "ROM") into ram.

If this is true, it means that we can't just upgrade the SD card in order to speed up boot times, since class 10 is already pretty fast.

My next steps will be to locate the boot sector, inspect the disassembly, confirm my suspicions about the boot sequence, and then get to work on understanding the main program.

In theory, it should be possible to figure out a way to spoof the firmware upgrade routine into modifying the contents of the sd card. If this is indeed possible, then we will be able to access (modify) the contents of the 4gb rom without cracking open the case.

Will keep y'all posted once the block copy is done.

[maranite]

More news... I've completed the backup using two different tools (linux's dd and Window Disk Imager) - both images are identical...

Quickly inspecting it under a hex editor:
> first 4 bytes spell "KORG"
> no ASCII present (i.e. looks like firmware is absent)
> binary patterns suggest raw wave/sample data
> so far, no obvious index / file allocation table / boot sector
> meaningful data ends 2.54 GB into the image.

I'm not sure where Korg are hiding the other 1.3GB of samples that the Krome supposedly has in it's "ROM"... unless they store the samples compressed (doesn't look like it), then there's a descrepency between what they claim and what I've found on my Krome's SD card. Its unlikely that the remainder of the samples reside on a 1.3GB ROM chip.

[Kromeheaven]

cool information
I think, I will open it too !!!!

[maranite]

Cyph... two things worth knowing:

1: The screws on the metal plate (keybed) do not need to be removed.
2: You can gently lift the cover (slightly) to get access to the sdcard. You dont need to disconnect any cables.

My unit booted perfectly this evening after I put it back together, so it seems relatively safe to temporarily remove the sdcard.

Good luck!

[maranite]

Hmmm this is really frustrating. .. the compression on the firmware upgrades has me stumped, and now the contents of the sdcard has me stumped too.

It looks like the sdcard contains pure audio sample data.... no file headers, no file system, no boot loader, nada.

Hopefully Cyph can figure something out with respect to the contects of the sdcard.... I'm probably going to refocus my efforts on understanding the firmware. In my opinion, if the sample data on the sdcard is not self describing / self contained, then its pointless to fiddle with it, because the names and locations of the sample are stored elsewhere in the Krome.

[Kromeheaven]

arg... I can't find the time to open it...very busy at work

@maranite : do you know if there is some kind of jtag or serial RX/TX connection that appears on your krome motherboard?

This is pure speculation but if any, this should be interesting to try a direct connection or a console...I suppose that, then, we could learn many more things about our krome

[maranite]

Hi Cyph,

I didn't take a very close look at the motherboard because I didn't want to disconnect any cables. I did look on the pcb for any pins labelled jtag, but didn't see anything. I wouldbe rather surprised if Korg haven't disabled jtag - they seem to have gone to lengths to obscure other areas.

Good news is that I'm making headway on the firmware. Look like they use a Lempel-Ziv derived compression algorithto compress the firmware... its a proprietary implementation, but I'm getting a handle on the mechanics of it. Once I've decompressed the firmware, I'll runit through Hexrays to take a look at how it all hangs together. Maybethen I can give you more answers about how Krome sees its own sample format.

Will keep you posted!

[jabberpony]

My display died this week. I'm thinking about trying to replace it myself and I'm posting in this thread because the people here have some experience with opening the case. Any advice on whether this would be a relatively easy project? I found the part online at Parts Is Parts for $150.

BTW, symptoms are: backlight is working, but display is dark. Touchscreen still responds and beeps, but of course I can't see what I'm touching.

I'm also trying to figure out if I can/should backup before I do this repair. Can I do that with the editor on my computer (which I haven't figured out how to use yet) without being able to see the touchscreen?

Thanks!

[jabberpony]

Well, as it turns out, I'm still under warranty. I got an extra year by registering within 90 days of purchase. So, I'm gonna take it to my local service tech.

[rovito]

Any updates?

[jabberpony]

Local factory-authorized tech replaced my display with a new one. I'm back up and running and good as new.

[rovito]

So the display its self failed? Not the board or software issue?

[marct2009]

Sorry I would've supplied more information but I didn't get any notifications. It looks like you guys have a good grasp on what's going on inside of the krome now. Hope my pictures helped. However I'm STILL having issues with my krome. After receiving help from someone I loaded the data onto a new microsd card and I still get error messages.

FX DSP Write Error

Does anyone know what this means? And what should I look into repairing? I'm far outside my warranty so I'm on my own on this one.