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Title: EII RS422 communication problems Post by: wintermute on April 02, 2008, 02:52:46 AM Hi everyone!
This is my first post here. Great to see a forum that has an EII category. To give you a short history of the odyssey I've been through I start with the fixes I had to do after buying my EII of ebay. 1. problem the EII had was some dead switches and output jacks. The switches and jacks can be bought from DIGIKEY in the US. The part numbers are Jack: SC1122-ND Switch: EG1321-ND (black). If you live in Germany and want to save some money I recommand ordering the Jacks at RS-Electronics. The Switches can be cleaned in some cases. Just solder them out, open them and clean the contacts inside (its a painful job but it works). 2. After a while using the EII I noticed the scratchy sounds already described in this section. I tracked down the defective RAMs and exchanged them with new ones form Reichelt Electronics in Germany. They still seem to have them in stock. 3. The diskdrive 1 was not responding. This was a very simple problem since I just had to clean the head inside the floppy drive. I used some Q-tips and spirit to do this. After fixing all that I got a EII in great working condition... (http://www.robotsinmotion.com/images/EII.jpg) Next I wanted to do some modifications :) My EII is serial Number 326 so it has a Rev.0 board inside. This means I can not hook it up to my Mac without soldering a RS422 Mac interface. What I did was etching some small board to fit excactly inside IC108 and IC132. But heres the problem...the board does not communicated with the Mac. The cable I soldered is fine and the original RS232 interface works perfect. I tested that with the debug EPROM and I was able to communicate and do some test routines. All connections on the Mac board seem to be according to the schematics. I even exchanged the metal resistors with carbon just in case this could be the cause. Now I run out of options. I simply have no idea what the cause might be. What I realized was that if I connect Pin 22 of IC107 to 5Volts (as described in the troubleshooting manual for the RS422 interface) IC132 (the transmit IC) gets very hot and I think it dies. I also checked if all kludges are done to the EII and that is fine as well. Scanner and Main EPROM are fine. OS is the correct version as well. I also tried about everything on the Mac side. Appletalk on/off, Mac Mode on the EII, no MIDI cables connected you name it... What could be the cause? Anyone here who built the MacInterface by himself? Anyone with similar problems? Please help! This is getting very frustrating :( Title: Re: EII RS422 communication problems Post by: esynthesist on April 02, 2008, 01:51:51 PM One of my EII's came also with a REV.0 board. The RS422 additional board was installed but it didn't work, so I also received the "Cannot communicate with EII" error on the Mac.
The reason for this was - indeed - a blown transmit chip. I realized this after measuring all voltages on the DB25 connector pins: some of them didn't match the range as specified in the EII RS422 document. Another indicator was that playing the little keyboard in the SoundDesigner for EII software actually worked. This means the EII played what I instructed it to play on the Mac (note on/note off). Which meant that Receiving signals on the EII worked (MIDI via RS422). Conclusion: transmit chip was dead. We replaced it and now everything is fine. Note that there are no safety buffers in the circuit between the connector and the transmit chip, so a small amount of "static electricity" on the connector is sufficient to blow up the chips (at least that's what my repair guy said, he actually said this RS422 board is very poor design by E-mu :-) Maybe this helps ? ///E-Synthesist Title: Re: EII RS422 communication problems Post by: wintermute on April 02, 2008, 03:30:50 PM I finally figured it out :D
The problem was that I did not connect PIN 8 of each IC (transmit and receive) to ground and PIN 16 of each IC to +5Volts on my self etched board...this was not covered in the RS422 schematics and I simply forgot that the ICs needs a voltage supply as well ::) . Heres a picture with all the kludges...maybe I will etch a clean one some day. (http://www.robotsinmotion.com/images/RS422.jpg) Anyway...SD4EII finally works... and I love it!!! Anyone want to share EII banks ;D Title: Re: EII RS422 communication problems Post by: Elmbeatz on April 03, 2008, 05:36:41 AM WOW!
Congratulations! I still got a second EII which has rev0 boards.. I haven't tested that one with SD yet , because I have a mint rev1 EII which I mainly use and which is working superb with SD. I don't know if the rev0 has any RS422 Modification yet. Have you made that little modification circuit completely on your own? I'm not a technician at all, so for me, building such a circuit would be a lifetime achievement ;) nevertheless, I would be pretty interested in modding the rev0 EII... Greets, Elm. Title: Re: EII RS422 communication problems Post by: wintermute on April 03, 2008, 06:05:54 AM Hi Elm,
yes this circuit ia all home grown :) Maybe I can do some more PCBs...but first I need to fix the errors on the design. Designing the circuit after the schematics was hard because I couldnt read some of the PIN numbers there. So I had to dig out the IC schematics and verify all the corresponding PINs to the schematic. Then I did the Layout...but there were still some errors after etching due to my stupidity ::) . Anyway, it works now and I already closed the EII frontpanel. There is still one modification that really interests me...I want a built in EPROM switch to change between EII Main and Debug ROM. While searching for the stupid error on the PCB I played a little with the Debug Mode and a terminal. Pretty funny what you can do there...testing...read disk to memory...read the memory...activate Input and Output aso. Btw. do you have some EII libraries you want to swap via FTP? Cheers Title: EII RS422 communication problems Post by: sheever on July 30, 2008, 03:20:01 PM 2. After a while using the EII I noticed the scratchy sounds already described in this section. I tracked down the defective RAMs and exchanged them with new ones form Reichelt Electronics in Germany. They still seem to have them in stock. hey, i am new here.....so i am happy to be here and may you can help in my problem... the main problem what i cannot figured out,emu havent got a sounds just few days ago...only pukks and analogue noises when i try to playing on it. would be great any opinion... i can send that noise which come from the sampler if its help.... thanks! Title: Re: EII RS422 communication problems Post by: ARES on March 24, 2022, 02:56:10 AM Hi to all,
I've an EII rev board 0... i read that you have modified it to rev board 1 ... How have you done ? Can you give some explication ? It will be fine :-) Have a nice day. ARES |