Korg Electribe ER-1 mkII repair

[feedback.loop]

This Korg ER-1 had a burned 5V DC-DC converter, which, most probably, killed some other important parts such as the micro-controller, DSP and memory. The DC-DC converter was repaired, but there were no signs of life, and the DSP seems to run too hot. At the moment this looks beyond economical repair.

[Ordinaryman1971]

Did you price the DSP replacement? Any availability?

[feedback.loop]

I see some on AliExpress for $25-30.
I am afraid that having no copy of firmware, it does not make much sense to order expensive parts.

[LateLesley]

What about if you could get firmware? It's not free though, and might make it too pricey still.

http://electribe.cc/wp/about/

[feedback.loop]

What about if you could get firmware? It's not free though, and might make it too pricey still.

http://electribe.cc/wp/about/

First of all, this is an update to load through MIDI assuming a working machine with some sort of a boot loader in it at least. I need an image of the flash memory, which is not the same.

[feedback.loop]

Got myself a TSOP48 adapter for TL866 programmer.
It was a part of a $22 set.
To be continued...

[feedback.loop]

Desoldered the flash. It is alive! Now I think it makes sense to proceed. I will order replacement MCU and DSP.

[LateLesley]

Awesome! Good luck with the repair. Look forward to updates.

[james_s]

I've fixed a couple of these that thankfully were less severely damaged. In both cases I'm fairly certain someone plugged in a power adapter of the wrong polarity. For reasons I've never been sure of, music gear seems to almost all use the weird center-negative power adapters while 99% of everything else is center positive. People assume that if the plug fits that it's ok to use which in this case obviously it is not.

[feedback.loop]

No, wrong polarity cannot kill this thing. There is a very simple and effective protection - a diode right after the power connector. It drops a few hundred millivolts, but who cares.
However, a higher voltage can kill it. Say, above 16V can be fatal for this DC-DC converter chip.

[james_s]

I wonder if they revised it and added a diode? Or maybe they were a different model, but I know they were Korg Electribe devices. Pretty sure the ones I fixed didn't have a protection diode but perhaps they did and it was overvoltage that zapped them.

[feedback.loop]

It works!



The firmware is attached.

[james_s]

Awesome! Nice job!

So it turned out to be the MCU and DSP?

[feedback.loop]

DSP and at least one of the memory chips, maybe both, and maybe MCU as well, but it is not clear.

[feedback.loop]

A couple of red LEDs on the front panel have lenses broken off. These seem to be Panasonic LN282RPX, which are obsolete.
https://www.digikey.com/product-detail/en/panasonic-electronic-components/LN282RPX/P547-ND/410764
Any ideas where to get them?
Thanks.

[fzabkar]

The firmware is attached.

Did you get hold of the firmware update package? FWIW, I wrote a tool to convert Roland's 7-bit MIDI formatted firmware binaries to 8-bit flash BINs. Perhaps Korg's format is similar?

[Whales]

Aww, those LEDs are cute.

Do you need anything more than the cylindrical end?  Would a thin 3mm LED held a bit taller do?

Unfortunately this will give you a different brightness and possibly a different colour tint.  It might be worth considering the option re-LEDding the whole board, as distasteful as that might sound.

[LateLesley]

Any chance you could use ones of a similar 2mm form factor? These don't seem quite as long I don't think, but might do the job?

https://www.ebay.co.uk/sch/i.html?_osacat=0&_odkw=2mm+led+round&_from=R40&_trksid=m570.l1313&_nkw=2mm+led+round+red&_sacat=0


EDIT : I found these, which are 8.0mm high, instead of 7.9mm?? https://www.digikey.com/products/en/optoelectronics/led-indication-discrete/105?k=&pkeyword=&sv=0&pv966=282200&sf=1&FV=37%7C395219%2C-8%7C105%2C525%7C395219%2C2029%7C122870&quantity=&ColumnSort=0&page=1&pageSize=25

But I see their mcd rating is a lot larger....

How about these? A little shorter at 6mm and dimmer, but closer to the original specs? https://www.digikey.com/product-detail/en/lite-on-inc/LTL-1214A/LTL-1214A-ND/3198382

[feedback.loop]

Thanks for suggestions. I have seen the ones with flat top. I would think they should fit, but they will look different and probably will have different color and brightness. Should be fine if all are replaced - 17 red and 5 green ones.
I still hope to find Panasonic ones.

[feedback.loop]

The firmware is attached.

Did you get hold of the firmware update package? FWIW, I wrote a tool to convert Roland's 7-bit MIDI formatted firmware binaries to 8-bit flash BINs. Perhaps Korg's format is similar?

I am not sure what are you talking about. What problem are you trying to solve?

[LateLesley]

Thanks for suggestions. I have seen the ones with flat top. I would think they should fit, but they will look different and probably will have different color and brightness. Should be fine if all are replaced - 17 red and 5 green ones.
I still hope to find Panasonic ones.

Ok, I did a bit of googling. I found this place which says they have stock.

https://ph.infinite-electronic.hk/product/Panasonic_LN282RPX.aspx

https://www.components-store.com/product/Panasonic/LN282RPX.html

I found several similar links, it seems all roads lead to HK for stock.

[feedback.loop]

I do not know these sites. They might be fraudulent.
http://www.erai.com/ERAI_Blog/3153/__Fraud_Alert__High_Risk_Websites_That_Take_Your_Money_and_Run_
They are not in this list, but have very similar names.

[LateLesley]

Well, yeah, that is always the danger of going outside the known good suppliers.

And looking at the fraud page, it does look like the logo and name have similarities. Good catch. And A good warning to all us hobbyists.

Apologies for linking to them.

And thank you for the warning.

[feedback.loop]

I finally received a 10-pack I bought on AliExpress for $1.20 (1.92 with shipping) to give them a try.

https://www.aliexpress.com/item/32819577430.html

As I expected, they have slightly different color (brighter red), they are slightly longer, not rounded, and noticeably brighter.

I believe this should work fine if all LEDs are replaced, including green ones.
If someone really wants to do fine adjustments, in the unit they sit on spacers, so in principle they can be lowered, and they can, perhaps, be rounded, but that is a lot of work. I am not going to bother. They stick out a little, but it does not seem to be a problem to me.

So I am thinking about ordering one more 10-pack of red ones, and a 10-pack of green ones, and replacing all of them.