Troubleshooting tips for 4-pole Mission Edition

I got mine built yesterday. I started from the filter couple days ago. Bought the common parts from reichelt. At first i thought that they did some serious over packing as they included their whole catalog(!) and had put all different types of parts to different bags and labeled them. Many bags had only one component etc…
But when i started to build it i noticed how convenient it was. I just checked component values from board and took corresponding part from the bag. No need to check resistors with multimeter etc… (i trusted their labeling, i hope that was not mistake).
This was easiest Shruthi-1 that i have built so far. BUT, that didn’t prevent me from ruining it!

I was so excited about how it would sound that after i had made 4-PM filter board i run to test it with my earlier Shruthi-1 (with SMR4 filter). I replaced SMR4 board with 4-PM filter and it booted nicely. I saw how Wolf’s red eye went to bright red. :slight_smile:
While testing it, 4-PM filters regulators touched contacts from one of the switches in control board and caused short circuit!

I didn’t noticed that regulators can touch legs of some switch until later, i just wondered what it does and how. Like why that led in the wolf’s eye is lid some times right after power on, then next time it’s not etc. (At that phase i didn’t knew that it was made to do that kind of stuff, i just read that from another post…).

What that short circuit did then? I think i noticed it after that older shruthi-1’s control board didn’t boot anymore. It went to “waiting firmware mode”. As it is called by pressing S6 while power on, i concluded that regulator did it mistakely.
I tried to send firmware to it and it seemed to work, i got update process done and display showed normal characters again.
But it didn’t react any button presses anymore. And after power off, screen went to blank again.

So i clearly broke something from control board.

Today when i got 4-PM control board done and tested filter board with it i noticed that it does not change its filter mode. It can be changed to anything but it does not make any sound difference. Resonance flavour worked correctly. I heard the difference.

BTW. i got filter mode changed occasionally by at first changing mode value, and then turning power off. When i turned power back on, it was changed. Not all times though… Couple times it changed when i moved boards a little. That made me suspect that connector is broken, but i couldn’t find anything. Besides there is not much to break. I tested connections with multimeters “peeep” mode.
Once it changed from HP to LP when i was removing power cable.

I replaced 4-PM filter boards regulators as i had few extra parts, didn’t have any effect. I also tried to swap those chips that those two filter boards had in common.

Thought: could it be that short circuit between regulators and switch caused some chips to fry in both boards? Like M74HC165 at the control board?
I have no idea where to look in 4PM filter board. Like i said, everything works in it except changing filter mode.

I just replaced that 74HC165N with new one and it brought that SMR4 Shruthi-1’s control board back to life. Thanks! All items are working here again. =)

So you can access the 2nd Filter Page? CUtoff and Resonance working?

If you can’t see the 2nd Filter Pages set the Filter Type in the System settings to 4pm :wink:

If so the next suspicious Spot to look at is the Filter Boards 595 - if you have a spare, replace. You may also probe the Outputs of the 595

If it seems to work next Step would be replacing the 4051 /4053.

Yes, i tried to tell that by saying “(System page had 4PM chosen.) It can be changed to anything but it does not make any sound difference.” Sure that can be unseen as my post was a bit long.
How should that pdf be used for troubleseeking? Correct voltage values were given instructions. I rechecked those without chips and with them, they were OK. BTW. At first i got short between +5v and ground from leftmost TL072. It disappeared by itself (yeah, sounds very professional) while i was metering. I resoldered it’s joints even if there were no any visible mistakes. I did careful soldering at the first place.

I don’t have spare 595 or 4051 /4053 chips. =/
Is it possible that short circuit could have damaged other parts as chips? If that is rare i guess that it would be good move to just order those chips that are most commonly to get faulty in this kind of situations, all at once?

I still need to buy parts for polivoks filter board. I could add extra 595, 4051 & 4053 chips to that order. How about that V2164D?

3 Bunches of Things to have in da house all times:

  • Pasta, Olive Oil, Gralic, Chili, Parmiggiono
  • Box of Beer / Bottel of Wine
  • 7805, 7905, 595, 4051, 4053, E12 Series of Resistors, LEDs
  • very fast car with no top
  • tape recorder for special music
  • acapulco shirts
  • two bags of grass
  • seventy-five pellets of mescaline
  • five sheets of high-powered blotter acid
  • a saltshaker half-full of cocaine
  • a whole galaxy of multi-colored uppers, downers, screamers, laughers
  • a quart of tequila
  • a quart of rum
  • a case of beer
  • a pint of raw ether
  • and two dozen amyls.

Had to google what E12 means.
Ok. I BTW studied those color codes once but that was almost 20 years ago and i am not planning to do that again… i have to spend most of my time with IT nowadays.

I already bought those 7805 and 7905 regs for a while ago when i thought that they were missing from the kit. They were not, i just couldn’t find those from the bag where they were… so i got few extra parts. That Ebay seller sold those in bigger amounts only.

-Are those 595 or 4051 /4053 chip widely available?
-Any idea what to look in that damaged control board? Switches don’t work and display is blank after power on. LED’s 1-3-5-7 are lid.

About the "fried“ digital board:

You see this LED pattern because the Shruthi detects that S6 is pressed, so it boots in firmware update mode. Looks like the 74hc165 is fried.

About the filter selection problem:

Make sure the 6pin connection between the two boards is reliable.

Check that the voltage on the 595 Q0…Q7 pins change when you adjust filter mode and resonance mode. Seems to be the case since you can switch resonance mode! The 4051 seems to be the culprit if you can’t adjust filter modes.

4051, 4053, 74hc595 (4000 and 74hc series) are some of the most widely available logic ICs.

So 74hc595 is responsible about changing filter modes and 4051 resonance flavours? Or do 4051 affect on filter modes too?

I metered voltages between Q0-Q7 against gnd in 595 and they all gave 0V no matter which filter /resonance modes were active.
Chip’s pin 16 (vcc) had 4.91V

Those can be bought from EBAY too, seems to be pretty cheap, luckily. I bought both 74hc595 chips and 4051’s .

The 595 delivers the control signals for the 4051/4053. If all is 0 some of the Lines from the connector/Socket are not soldered correctly (had this issue on mine) ore less likely the 595 itself is faulty.

@schrab - LOL!

I feel that those solders are (near) perfect, so hard that is to believe for you as i am not familiar with the theory of electronics… i remind that i did soldering as part of my earlier job over 6 years and passed employers “soldering exams” where quality control ppl. were zooming our job quality with microscopes. If i know something about electronics it is how to solder. And something about ESD safety. But not much more. :smiley:

I also have checked that connector.

Connectivity tests (power on)

SMR4 filter:

+5 : +5
GND : all
OSC< : +5, OSC<
VCA< : all
F< : +5, OSC, F<
Q : all

4-PM filter:

+5 : +5
+GND : all
+OSC< : +5, OSC
+VCA< : all
+F< : +5, OSC, F<
+Q : all

Connectivity tests (power off)

SMR4 filter:
+5 : +5
F< : F
Q< : Q

4-PM filter:
+5 : +5
F< : F
Q< : Q


SMR4 filter:

GND 4,98
OSC 2,47
VCA 4,96
F 3,72
Q 4,96

4-PM filter:

GND 4,91
OSC 2,44
VCA 4,90
F 3,66
Q 4,89

Combination 4-PM control board + SMR-4 filter board works well.

What about the other connector?

Good question! :wink:

    • -edit- - -

That’s it! You perhaps guessed that i had not connected output expansion at all because i gave only measurements of the “main” connector.

BTW. i rechecked build instructions and now i saw this page:
It contains phrase that reminds connecting expansion connector on the bottom left of the control board. Didn’t see that before cause i used just this filter page as instructions:

I used same digital board instructions this time as with SMR4 Shruthi-1’s. I had read from forum that all digital boards are similar so i thought that it doesn’t matter, it should work. And because it doesn’t say that expansion connector must be connected i was misleaded…

When i shorted those regulators to legs of that switch i was immediately suspecting worst case scenario; that both boards were damaged. I’m SO happy that it wasn’t the case!

My new 4-PM works perfectly. I’m running sequence now while testing new filters. Filter mode: phaser and flavour: wobbly, small hint of LFO modulation and it sounds awesome! As well BP+Wobbly. I have not tested all yet, so far all sound great addition to the palette.

Thanks for help. =)