Programmer Not Cooperating

So I built a programmer on perfboard and I can’t get it to work. I have checked all the pins many times and checked that each chip gets power and ground.
The symptoms are:

  1. The pots don’t do anything
  2. The Shruthi numbers all jump about when the ‘cv.mode’ is set to programmer just like when the programmer is not connected.
  3. The center ‘wiper’ pins of all the programmer pots jump about in voltage when the ‘cv mode’ is set to programmer but do not when set to the other 2 modes.
    Unfortunately, I don’t know enough about digital chips to troubleshoot any further. Are there any obvious causes of these issues?

thanks, Martin.

Brave guy building it from the schematics!

Cv set to Programmer and the values are floating means nothing is connected to CV1IN on the Digital Board.
First try to short CV1 on the digital Board without Programmer, CV set to Programmer Mode. You should read a steady 0 for each Parameter.
If so your Shruthi works alright.

Jumping voltages on the Wiper Pins means you have no steady 0/+5V Rails at the Pots, did you connect the Pots rails somehow to the 595s 137s output??

I am a brave destroyer of all components! :slight_smile: When you say ‘short CV1’, I’m guessing you mean to IN1? Shorting to GND does nothing, shorting to 5V does nothing, but shorting to IN1 sets patch parameters to 0.

The rails on the pots are all correct at 0 / 5V, but the other pins on the 4051s all jump about. Pins 1, 2, 12 -> 15 on the 137 jump about so do pins 1, 2, 3, 4, 15 on the 595. I thought it might be bad chips, but they all seem to have input and output. Could bad bypass caps on the 4051s have this effect?

thanks for the help!

Funkyfli, I too had this exact same issue. I spent hours testing every point. Turned out I had accidentally shorted the +5 rail to a pot, frying out all the 4051’s. Once I swapped em out, the issue went away. May not be your issue, but that’s what worked for me.

Good luck!

hmm… I did check the voltages on the ic sockets before inserting them. But, yes, I may have to invest in new chips as a last resort.


First, please follow up to the Programmer Thread as i don’t want to have the Forum cluttered with Programmer Troubleshooting Threads, it should be all in one place, hence this is my last posting in this Thread.

I think you have absolutely no clue how the Programmer works :wink:
Read Post #2 on Page 1 of the Programmer Thread

The pins jumping are Digital Chip Select and Adress Lines, so its natural for them being either 0V or +5V. 137s Pin 1,2 is Adress in, Pin 12 > 15 are the ChipSelect(Enable) Lines for the 4051.

Pin 1,2,15 on the 595 are the Adress Bus Lines for the 4051s, 3,4 is decoded by the 137 for the ChipSelect Enalble Lines.

On the 4051 the Pins 9, 10, 11 are the Adress ins, connected to 12 >15 on the 595, hence be “jumping”. Pin 6 on the 4051 is the Chip Select/Enable IN and connected to one of the 137s Pins 12>15 hence jumping, too.

Pin 1,2,4,5,12,13, 14, 15 of each 4051 should be steady something between 0-5V depending on the associated Pots setting.

Pin 3 of each 4051 (all are connected) is the output of the 4051s and should be only connected to shruthis CV1 in. Should be jumping to various Values between 0-5V, depending on the Adress Lines/Chip Select selection of the corresponding Pot.

See here:

BLUE: Steady GND
RED: Steady +5V
GREEN: digital Adress/ChipSelect Lines, should be pulsating 0v/+5V
ORANGE: Analog Line from the Pots Wiper, should be steady something between 0V/+5V, depending on the Pots setting and change with Pots setting
YELLOW: CV to the Shruthi, should be pulsating something between 0V/+5V, depending the addressed Chip/Pot and Pot Setting