Juno G LCD. Help me help you.

[BustSkunk]

I'm tone deaf, I'm completely useless musically, I'm an electronics engineer & I'm trying desperately (and failing) to avoid getting involved with the repair of my brother's Juno G, which has a duff LCD.

Does anyone have *any* info on the display itself please?
Schematic, or reverse engineering of the display protocol.

I have the Juno-G service notes (April 2006) and they do not include the schematic for the LCD module itself.

It may be relatively painless to connect a generic display to something like an Arduino or PSoC and get it going. I'm not promising anything but the more data you chaps (and chappesses?) can provide, the more chance I have of a permanent fix.

[BustSkunk]

50 views and no replies. Oh well!

What I've found out so far...

The display is not manufactured by Roland. It is very probably not their deign. It looks like they used an off the shelf part from IDW. This explains the interstitial pcb used to elongate the flex. It explains why the LCD schematics are not in the Juno Service manual.

IDW, International Display Works were swallowed by Flextronic in 2006. Looks like IDW were headquartered in Rocklin CA & manufactured in China. Flextronic don't have a site in Rocklin, neither do they appear to be offering LCDs on their corporate website. I think the chances of finding the right person to approach in Flextronic to ask for a datasheet are about one in 7 billion. Possibly a little less, if you could work out how to exclude the portion of the global population who don't work for flex.

I really don't want to reverse engineer the protocol, which leaves the option of repair.

Yesterday my father stripped the Juno down and brought the display round. Sure enough the flex ribbon pernamently attached to the display had cracked. The cracks were at the pluggable end of the flex, right at the rigidiser as you'd expect. Of the 18 conductors 14 were cracked.

We remopved the lex at the PCB end. The black resin was removed using a Dremel with a ball shaped engraving attachment. A jewellers lopue was used to ensure the PCB wasn't damaged. The cable was cut off in this process.

I stopped just at the point that the soldered cable tails became visible. The cable tails were removed & the PCB cleaned using desolder wick.

I will now attempt to souce an SMT Flat Flex Cable socket to solder to the PCB, Then one long, replaceable FFC can be used to connect the display to the Juno. Since there are no mechanical mounts for the socket, it may need to be glued as well as soldered.

I'll update with results and component part numbers when done.

[Leo Castro]

Nice work! Hope it works. If you can, make a video or take photos during the process, maybe some users can attempt to fix theirs, and i know there are a lot to be fixed.

regards

[BustSkunk]

Thanks!

The new parts were fitted today, and they did not fix the display.
For reference, they were:
https://www.mouser.com/ProductDetail/mo ... cycode=GBP
&
https://www.mouser.com/ProductDetail/wu ... cycode=GBP

The display appears to have four quadrants. North East is fine, the others aren't. They come and go. The backlight isn't alive.
So sadly, I think the display itself is faulty. It's not a repairable module.

To be clear, the cable attached to the display was broken, no shadow of doubt there. I wasn't the first person to attempt to repair this kit, so I don't know if the display cable was damaged as a result of handling during the repair attempt, or even if the broken cable caused damage to the display electronics.


So, I'm going to have a go at reverse engineering the protocol used to talk to the display & see if I can knock up an interposer board that will allow A.N.Other not yet chosen display to be used. Thiw work will allow display modules to be replaced in other broken Juno Gs.

I have schematics for the Juno. I'll repeat my earlier request. If anyone has any data on the original display, please pass it on.
If you know someone who might have datasheets, please point them at this thread.

It's going to be a couple of weeks before I have anything else to add to the thread, but I will update when I have something worth saying.
So much for not getting involved!

[Leo Castro]

I'm sorry to hear that
I don't have any tech information of the display.
Hope you can reverse engineering the display "language".
Waiting for the 2 weeks update.

Regards

[dpi]

I found these service notes. Not sure if the included schematics will help any

http://monitor.espec.ws/files/juno-g_se ... es_220.pdf

[eduposada]

Hey, i liked what read on this topic. In spite it didn't solve the problem yet, I am glad there is still people trying to manage this. I will also try to find some material about it. If I find, I will reply here.

There is another topic of a guy who is trying the same thing, using raspberry or arduino to emulate the screen with an external device, comunicating with the Juno by midi. Maybe you all can join efforts. The post here is as following:

Is this a possible solution for LCD Juno G screen??
Post by rrete » 17:54, 8 December 2020

By the way, I am living in China right now. Is there any information about the company which produced the displays? I could try to find something with them.

Thanks for your effort!

[BustSkunk]

And I'm back almost two years later.
As you've probably guessed, I stopped working on this. A combination of a broken logic analyser and a second fault on the Juno G made it very difficult to make any progress.

I have just hooked up a replacement LCD using dpeddi's solution. It works.

Please consider this thread closed. Anything new should go in this thread:
https://www.forums.rolandclan.com/viewt ... 12&t=58712