Emax

>>> meanwhile i switched to an Emulator II+HD to do the tests, because i know that works well with SD thru DB25. is it fair to assume that it has a healthy port and will work with the EMXP too?

Yes

>>> since the UA9637AC is not available around, i replaced it. i did not use any capacitors and resistors though. if there were any other reasons, please let me know, i need to check that.

The resistors and capacitors are added for voltage dividing (changing levels) and for shaping the signals.

From what I read now, you actually didn't use any of the components and any of the schematics of the published EMuSer specifications.
The Teensy++2.0 is the only component you used which is kind of "supported" by the EMuSer specs.

I'm not saying that alternative circuits with different driver/receiver ICs and different (or no) resistors and capacitors will not work, but you probably understand that *your device* is not  an "EMuSer" for me. 
So I can not give any support for it and of course I can also not say or guarantee whether it will ever work with any E-Mu sampler. 
I hope you understand that I will not go into the detailed specs of the MAX485 and SN75176B (or buy them) to check if they make sense on the level of expected signal shape and signal level.


But you are right that that the components from the EMuSer specs are a little bit harder to find than the ones you used. 
However, they are usually still available on online electronics websites. I was even able to order them in a 'brick and mortar' electronics shop in my city a few months ago (I had to wait 1 week).
And the Teensy2.0 is also available again on PJRC.COM and it even dropped in price :-) !


One last note:
If anyone wants to build the EMuSer, I strongly recommend to follow all instructions and specifications from the contruction manual. Or at least the ones regarding the electronics. If not, you are actually designing another device which is a great initiative but which should be considered another project.

Good luck.

///E-Synthesist









--- In emax@yahoogroups.com, "Adam" <fake@...> wrote:
>
> well, it starts to make sense! it really looked disappointing, now there are new things to check. 
> 
> meanwhile i switched to an Emulator II+HD to do the tests, because i know that works well with SD thru DB25. is it fair to assume that it has a healthy port and will work with the EMXP too?
> 
> i put this back to the bench and will check if there were any signals coming in and out on the TX-RX stuff. i havent included the LEDs on this design.
> 
> since the UA9637AC is not available around, i replaced it. i did not use any capacitors and resistors though. i assume you used it to shape the signal (apart from those to support the LEDs). if there were any other reasons, please let me know, i need to check that.
> 
> i am going to list the short description of my version in a very easy way. everything is connected direct, no resistors or capacitors used. please see below if you were interested in.
> 
> "So, what error do you actually get in EMXP ?   "
> 
> When receiving from the EII it says: Errorcode 990. There is a communication problem with the EII. ReasonCode is 3.
> 
> i am going to post it quick, so maybe you had more time to check and think, and now i'll return to measure the circuitry.
> 
> and now the connections:
> 
> 
> 
> RECEIVER (RX): MAX RS485
> ---------------------
> TXD+ (Emax: pin8) -> Teensy RXD+ (RS422:3) -> RS485:7 (B)
> TXD- (Emax:pin9) -> Teensy RXD- (RS422:4) -> RS485:6 (A)
> GND (Emax:pin3) -> Teensy (RS422:5) -> RS485:5 (GND) 
> RS485:pin1 (R0) -> Teensy PD2 (RXD1)
> RS485:pin2 (NRE) -> L 
> RS485:pin3 (D) -> L  
> RS485:pin4 (DI) ->  not connected 
> 
> TRANSCIVER (TX): MAX RS485
> ------------------------
> Teensy TXD (PD3) -> RS485:pin4 (DI)
> RS485:pin6 (A) -> Emax:pin5 (RXD-)
> RS485:pin7 (B) -> Emax:pin4 (RXD+)
> RS485:1 (R0) -> not connected
> RS485:2 (NRE) ->H
> RS485:3 (DE) ->H
> 
> CLOCK (CLK): SN75176B
> ------------------------
> CLK (Emax:5) -> SN75176B Pin6 (A) 
> SN75176B:pin7: B -> L
> SN75176B:pin1: R -> Teensy PD5  (XCK)
> SN75176B:pin4 (D) -> not connected
> SN75176B:pin3 (DE) -> L 
> SN75176B:pin2 (NRE) -> L
>