e-licktronic Forum

Hi, I try to trigger my SH-101 with the trigger output and it triggers some of the steps only. Some steps work, some others don't. And it's random. Anyone with the same problem?

Anyone can test the trigger?

I have my trig out permanently connected to my 101 and it's been solid.
You have a scope to check trig voltage or another device with trig out to verify the 101 input is ok?

Ok, tested it again and it works fine on the SH-101 when connected to the Gate input. However, it behaves like stated above when connected to the Clock input on the SH-101 or Juno 60. Is the gate voltage from the Nava too low to use as a clock trigger?

Thanks,
Ed

I've been using the clock input.
The 101 service manual says 2.5 V or higher for both clock and gate.
The Nava trig out is supposed to 5V but I haven't actually measured it.
If you can verify that your Nava trig out is actually 5V, then I would guess that your 101 clock input needs repair.

I gonna double check the Voltage of the Nava trig out...

I have the same problem too. I cannot trigger the clock of SH-101. I have a very low Trig-1 output voltage which is way below 2.5v, I have 0.07v only. Which part of the Nava should I check to see if there is a problem?

My Nava output a 5V trigger, and it's not enough for my MFOS ADSR that requires 10V, i need to amplify it through a VCA in order to trig the ADSR. I looked at the schematic to see if it's possible to output 10V using the existing circuit, but I don't think it can be achieved without adding an additional op amp. But it's not the subject here haha.

truman_k@yahoo.com wrote: Which part of the Nava should I check to see if there is a problem?

The 5V S-trig is generated at pin 38 of the Atmega (IC119), but i doubt there would be a problem here, you can check anyway. You should have a signal that is 5V, then goes to 0V at every trigger.
After that, it goes to pin 3 of J2 connector, be sure to check that the wire isn't broken.
Then, the pin 3 of J10 connector on the IO board is connected to a 47k res (R550) which is part of an inverter circuit with the 2N3906 (Q66), 22k res (R551) and 1k res (R552) (to get a V-trig from the S-trig provided by the Atmega). Check if resistors value/transistor orientation are correct, if solder joints are good and if it's the case, maybe the 2N3906 is faulty.

BastienL wrote:
The 5V S-trig is generated at pin 38 of the Atmega (IC119), but i doubt there would be a problem here, you can check anyway.
After that, it goes to pin 3 of J2 connector, be sure to check that the wire isn't broken.
Then, the pin 3 of J10 connector on the IO board is connected to a 47k res (R550) which is part of an inverter circuit with the 2N3906 (Q66), 22k res (R551) and 1k res (R552) (to get a V-trig from the S-trig provided by the Atmega). Check if resistor value/transistor orientation is correct, if solder joint are good and if it's the case, maybe the 2N3906 is faulty.

Thanks Bastien, maybe I need to trace through that path ...

Hi Bastien,

I have trace through the path. Here is what I found:

1) pin 38 of the Atmega (IC119) is giving 4.80v. *** But I don't see any significant drop of voltage to 0v on triggers
2) pin 3 of J2 connector is giving 4.80v
3) pin 3 of J10 connector on the IO board is giving 4.80v
4) The C leg of 2N3906 (Q66) has a reading of 4.80v
5) The B leg of 2N3906 (Q66) has a reading of 4.80v
6) The E leg of 2N3906 (Q66) has a reading of 0.08v
7) 1k res (R552) has a reading of 0.08v
8) 22k res (R551) has a reading of 0.08v
9) 47k res (R550) has a reading of 4.86v

I have replace the Transistor 2N3906 to a new one. But nothing change, I am still having a low voltage of around 0.08v at the Trig-1. And I am still stuck here.

And I have tested all resistor, they are giving the right ohm. The Transistor is in the right orientation.

what should I do next?

Please help.