Piano World Home Page Forums Our Most Popular Forums Digital Pianos - Electronic Pianos - Synths & Keyboards GEM RP90 successful repair

The CPU still hangs in the middle of startup sequence.
My piano had such symptoms when the RAM was broken, before the replacement. 8 lit diodes and row of gray bars on LCD.
I'd say, there are still broken traces on the board... And there is hope

Mind You, the board is double-sided and some traces are going from one side to another, through metallised holes. AFAIR some are under the chips.
All these connections have to be working too - and some might be damaged now.

I checked all of them with a multimeter, and I even didn't have the service manual back then, so I traced most address and data lines between CPU, RAM and ROM, what goes where.
When I was 100% sure of all connections, with the fresh RAM the board started at once.

Thanks a lot again for quick answer Kumi_27

You think that the problem is a broken trace? I'll do my best to check all the connections.

The rams will be ok while I solder broken traces? Or now that I turn-on the board they are corrupted and have to change them again?

My hope level have increases a bit seen that the symptoms were similars to yours

thank you

The problem with these old GEM boards is that RAM chips have backup battery without any protection. Other manufacturers put a diode in such circuit.
I suspect that when the battery dies, then the supply voltage of these two chips goes near zero, and the address/data lines still have around 5V (from CPU) - this causes burning of the RAM chips.
Only these two, because only the RAM is powered that way. And at that time the leak already caused damage to the traces.
Or maybe - I don't know - the leak shorts the pins. The RAM is just near the battery.

If You replaced the battery with a fresh one, there shouldn't be a problem with checking/soldering.
Of course, standard IC soldering rules apply - low power, preferred anti-static soldering iron etc.

Hello,thanks for the topic. Let me ask a simply question.
Anybody know if is possible today buy a new entire pcb 310603/1 board for GEM RP90??

By the way this is my first post here. ´My name is Jorge and I´m a piano technician in Granada(Spain).
We are sepecialized in electro acustic and vintage pianos.
If you want take a look here: www.facebook.com/rhodesjebi
Thanks and sorry my english.

I highly doubt it, considering GEM is out of the business for 7 years or so.

Well, there's the "New Generalmusic": http://www.generalmusic.fi/

A business man bought what was left of Generalmusic. That included emptying the ex-premises and shipping several containers of various stuff (like parts, documents, unsold stock I guess) that was still in the premises. But I don't know if that included spare parts -- especially for such an old model -- and would they be able and/or willing to help. I've never been in contact with them as my problem is a Casio and not a GEM.

I have a GEM RP150 (15 years old) which had last December a battery leak damage.

Following the Kumi 27 suggestion it could be repaired. First washed and cleaned the mainboard, but wasn't enough. So I bought and let replace the 2 RAM chips (Lyontek LY62W1024SL-55LLI as indicated). Put the board back inside the piano and switched it on: the GEM lighted up the LCD and displayed * REALPIANO * RP150. I'm very happy.

A lot of thanks for the contribution

Yay for another repaired GEM

Hi, I'm back.

as I wrote a couple of day ago, I could repair my GEM RP150, that now play again in all his features as a new one.
I have in addition one midi arranger and one midi/mp3 player. They work normally as well and are connected with the output jacks (L & R) to the correlating input jacks on the GEM RP150.
The RP150 work for this as a "mixer". It happens however a strange thing. While the piano sounds in a stereo configuration (the lower notes and effects are more to listen in the left speaker and the higher ones on the right, like in a concert) the sound of the external player are reproduced only on the left channel, the right one doesn't have any response. But if I play some notes they are to listen over the reproduced sounds in the correct space. Obviously the amplifier board was absolutely not effected in any way by the leak of the battery.
I checked all the jacks in several modes: right channel with right channel but also in reversed order (right out to left in). I tried each jack alone with a digital tuner: put the signal in the right in-jack, the sounds are reproduced in the speaker, in the headset and in the out-jack that I connected with a hifi but only on the left speaker. I put the signal in the left in-jacks and the sound is reproduced in the same way, only on the left speaker.

The piano (pieces played by me or the demo songs) instead are reproduced very fine with a super sound and a space effect.

I tried to disconnect and reconnect the cable between jack board on the rear of the instrument and amplifier board. But without effects.

I think there is some option in configuration panel but couldn't find any parameters. The 2 balance buttons on the control panel effects the volume only in split or layer mode regarding main sounds and the added ones.

I searched for a total reset procedure for the piano but could not find any. In the operating manual is described only to reset the presets sound style and the microtuning.

Somebody have one suggestion or a response?

Thank You to all in advance.

There is no software mixer nor any menu option.
The whole input signal mixing is purely hardware and if something is wrong, You have to check all connections, input jacks and wiring, because there is nothing more to it.
Of course, You need to use 2 mono jacks for L/R input signals.

https://bmamps.com/Schematics/Keybo...,_150,_200_Pianovelle_Service_Manual.pdf

Hi, it's now all ok.

I checked all the connections, cable on the board and did a lot of test with the jacks. Try left with left, righe with right and crossing them on the piano and on the source too. During one of these it was generated a "scratch" Just after the "bang" the sound become stereo with both the channels signals coming from the arranger and midi player working as usual. the internal piano sound worked already fine.

Now I can enjoy my GEM as a new one in total.

Many thanks for all

I am myself following Kumi_27's amazing steps to revive a Baldwin RP100 ... ordering the RAM chips soon, since cleaning up the tracks wasn't enough. Where did you get yours, carlettoz?

excuse me for the delay, I was out some days.

I could found the ram by http://www.farnell.com/ (by me in Italy it.farnell.com)

I search and ordered lyontek ly62w1024sl-55lli sram 1m 128kx8 2,7-5,5v 32sop

they were wery speedy and professional.

Hello all my name is francisco from spain
i have and old rp90 with the battery problem i change the rams the battery an one transistor , well the room ic is out totally some pins are missing if some one can help me sending the firmware for rp90.
I would be very grateful
[img]https://www.dropbox.com/s/ivgfqmsl49rk8kz/amd%20rp90.jpg?dl=0[/img]

I don't know why but my ISP doesn't let me share ftp folders. It worked some time ago and is not working now.

Anyway, I put the RP90 v2.00 firmware (and the upgrade) on Google Drive https://drive.google.com/drive/folders/0B-u-rs-jO1nYX3NGUEprMExacjA

Thanks thanks thanks

UPSSSSS¡¡¡¡¡¡¡ i can see two files Which one goes first or is indifferent, if the board are ok is no problem solder desolder but is in very bad condition
thanks

The 29F800 flash is a "dual mode" 1024K x 8bit / 512K x 16bit
My programmer used 16 bit "word" mode and swapped the high/low bytes. The other file (and the original RP100 firmware too) has "byte" order and should be programmed in 8 bit mode.
So the contents are basically the same, but with different byte order.
I don't know, what kind of flash programmer You might have. You should know what You're doing with it

ok ok i think one is the original firmware and the other the upgrade sorry

No problem
Like I said, "my" 29F800 original flash dump is a v2.00 firmware. You can program it to a new chip.
If You want to upgrade to 2.03, in the folder is the original GEM update file (UpgradeRP90-100-120-150from2.0xto2.03.exe).
Originally it was meant to upgrade the working piano using RS232 cable, as described in the pdf.
Inside are the ".mor" files (discussed earlier in this thread), so not the complete firmware file.