MD16

[Gordonjcp]

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=120269445793

Hohoho...  Wonder who won that auction?  Oh look, me! </gloat>

Seriously folks, full report on it once it arrives, ok?

[nochtanseenspecht]

congratulations ! is it a complete cheeta synth but without the case and power supply ??
you're lucky !
yeah keep us informed 

[Circuitbenders]

and i just cost you another £10 by trying to outbid you 

That seller was one of the original cheetah designers, sooner or later i'm going to get a replacement MD16 board from him to repair my battery leakage damaged MD16R 

[Gordonjcp]

Well, it arrived.  The firmware ROM isn't there, and there is extensive corrosion around the battery.  More updates as I work on it...

[Circuitbenders]

How bad is the corrosion? On a previous auction for an MD16 board I asked that same seller a question as to whether the battery was present or had ever been there, and he said that the batteries had never been fitted to those boards

[Gordonjcp]

"Quite Bad".  Pics when I find some HP7s for the camera ;-)

What I'll probably do is desolder the affected components, clean off the board and rebuild any damaged tracks.

Do you have a dump of the firmware ROM?

[Circuitbenders]

believe it or not i appear to have actually lost my MD16R and a mate has borrowed my MD16RP. 

I've searched around for about half an hour and i can't find the MD16R anywhere! It comes to something when you have so much gear secreted in various places about the building that you lose a rackmount drum machine!

I'm not sure i have the facilities for getting a dump of the firmware chip but i'll give it a go when i find the bastard. What kind of firmware chip is it going to be?

[Gordonjcp]

No idea.  Mine is completely missing.  27256, according to the workshop manual, so 28-pin JEDEC and well within the capabilities of most EPROM programmers.

[Circuitbenders]

Do you still need the firmware ROM for your MD16?

I'm having a bit of difficulty getting a dump from the ROM i have but I just won another board from that ebay guy and he's now selling them with the firmware ROM included. I'm not sure if its an original or a new copy but he could probably supply you with a dump.

Failing that i'm going to have a spare ROM when the new board arrives.

[Gordonjcp]

I do still need a ROM image, yes.  If you could grab a dump of the one on the board you just bought that would be excellent.

[djsynchro]

he could probably supply you with a dump.

heh... that made me giggle 

[Circuitbenders]

well, i now discover that i don't have a programmer that will actually accept EPROM's but i should have a willem programmer turning up next week with any luck.

The board i bought from ebay has arrived with an MD16R 2.06 firmware rom. I've pulled out the battery and replaced it with a new one after repairing or bypassing a couple of corroded tracks. I've got a MD16R that i bought a while back with a board thats just melted beyond repair by battery leakage so i stuck the new board into the empty case and it sprang into life and appeared to work fine. In fact everything internal works fine, you can edit the sounds and record patterns etc etc, but theres something horribly wrong with the midi.

At first i thought the midi was completely dead but i hooked it up to Midi-OX to see if it was actually outputting anything and discovered that most of the time when i hit the drum pad keys it outputs nothing but sometimes it outputs note off messages but no note on's, and other times it outputs random bits of undefined midi data or even pitch bend or Key Aftertouch data. Which is odd as the MD16R doesn't support either of those as far as i'm aware. I've had it working perfectly for about 5 seconds but then everything went odd again.

Does anyone have and idea whats going on here? Obviously something isn't working as it should be but its not my midi setup as i've done a cold start on both my MD16RP and this MD16R and the RP works via midi straight away but the R doesn't. Its not the firmware as i've tried a MD16RP 1.01 chip and an MD16 2.05 chip and it shows the same symptoms.

If something is damaged it seems odd to me that the midi would be outputting anything at all let alone random data

[Gordonjcp]

Damaged tracks to the UART?  Just a thought...

[Circuitbenders]

Good point, thats fixed the Midi output problem. The track from  the TXD pin of the UART to a diode just before the midi out socket seems to run under the battery area and had been corroded away.

Unfortunately the Midi input is still completely dead. I've checked all the tracks from the RXD pin of the UART and everything seems to be connected up. According to the schematics the midi in should be directly connected to the midi thru and yet i don't appear to be getting anything at the midi thru. I'm starting to think the opto-coupler U7 just after the midi input is dead.

back to the drawing board................

[Gordonjcp]

Thanks to Circuitbenders I now have an MD16R ROM.  Here it is, for your downloading, hexediting and burning pleasure:
http://www.gjcp.net/~gordonjcp/md16r.bin