Shruthi-1 wit 4Pole mission (BIG Problem :((

I have build Shruthi-1 wit 4Pole mission filter PCB

Now i have serious problem!

I check voltage on PCB wit only one IC and it is OK!

Then I put all ICs and join PCBs to connect to power adapter, 9V -500mA center positive
I used adapter from my Mininova synth it have same specification 9V -500mA.

First after power plugging there was little short (2-3 sec) “smoke” and circuit “smell” at Display board on left side…
It seems that is working but there is nothing on display :frowning:
When i press buttons light turn on
I didn’t get any sound… I don’t have time to risk overheating…
If i press display it shows only vertical lines (barely visible on touch only)

Other bugging thing is: On 4pole PCB parts IC11 & IC12 (look like aluminum coolers) after 10 sec start to get extermnly hot (it can burn finger)
That is reason why i don’t make display contrast because I’m afraid of damaging or burning other components…

One really really good person from forum
mentioned that there is issue with 4pm voltage regulators? Because LCD was draining too much current?
I don’t know what to do :(((

(To Use Better Adapter or New Display???)

Please if someone know what is problem or how to fix it please let me know.
Thank You all!

Looks like you have a short somewhere… Have you checked for a short between the +5V point and GND?

Only one row of IC sockets on 4PM PCB. (Like in official instructions)
Sorry I’m newbie :frowning: Where to check for more?

Thank you

Have you checked for a short?

But where? I don’t understand. Can you explain better I’m totally lame :frowning:

One method would be to take your multimeter (you do have one, don’t you? :slight_smile: ) and set it to the continuity tester. That’s where it beeps when it detects a circuit. You then place one probe (typically the one with the black handle) on ground, and then use the other probe (red handle) to test various points (e.g. the +5V point), by touching the probe to the test point. If your multimeter beeps, then you have a short circuit to ground.

Other folks please correct me if I am wrong, I haven’t had my full coffee dose yet!

This i understand.
Im youst produce music this is totally strange for me.
This is my multimetar, which selection to use for “continuity tester” ?

And about “ground” GND where to put probe for ground mode?
Do i need to turn on Shruthi or without power?
Thank you!

Use the mode at the very bottom, the one with the diode symbol one it. You should be able to enable the beeper mode somehow (long pressing one of the buttons? I don’t know).

Measure without power. There is a GND on the pinheaders that connect the two boards.

Thank you all.
I checked it. But still i don’t understand what I’m searching? When i put to diode tester, red on +5V and black to GND it is OK. ~500 units on multimetar.
When testing +5V wit red and other +5V wit black it beeps…

Please don’t smile i work wit music 20 years. But this is first time to learn some basics of electronic.
Let say i have shorts, how to fix that?
Can someone put picture wit places on board where to measure for shorts???
Thank You

Check the -5V supply rail as well. Basically you want to make sure that there is no direct connection between GND, 5V and -5V in any combination.

Awesoome! Now i understand! Do you think “spots” like on this picture? I tested but not for -5V
Is there other places that must be checked?
Thank you for this simple explanation.

Yes, those spots are a good point for measuring. You only need to check one red point vs one green point, one green point vs one blue point and one blue point vs one red point. They should all be not beeping

Hi everyone!
Thank you for understanding my mutlimetar and tips to check! I respect that!

I make test before 1 hour and i have some info and questions:

I think i got something :slight_smile:
All IC are on board and power is on. Everything shows ±5V

But IC7 “LT1054” have strange values, i don’t know does is that necessary or?
It shows between 12-13V but on other pins-legs is show 8-9V
i use ground-green from other ICs.

Best of all is heating! It is connected 5 minutes and temperature
is low and stabile, no burning-overheating :slight_smile:
Please what do you think about LT1054? Is it OK? Or witch pins-legs to use for reading values?
I don’t see purpose to remove all ICs and start measuring because there is no shorts and power values are they need to be 5V
I didn’t put main PCB this is only filter!

Here is another thing. When i join both PCB i see little on display name and version so for LCD i need only to adjust better.
But issue is heating in only10 sec it was warm and burning, like it will damage-burn all.
So i disconect power! And remove PCB
Strange! it can run tested 5-10 min on normal temparature but when i put main board it overheat in 10 sec…

I think the “problem” is on main-display board?
Thank you all!

If you measure -5V at the blue spots, the LT1054 is workink all right.
The problem is definitely your controll board. Have you made shure that the underside of the display is not touching any components of the controll board?
Next I would measure for a short (or the resistance) between +5V and GND at the controll board.
You can do that without the filter board connected. Use your multimeter in resistance mode (the range with the Ohm symbol) and measure at the board connector (+5V and GND).
You could also post pictures of your controll board (both sides).

I checked wit lens, LCD board is not in any touch wit control board.
I measure resistance like you write between +5 and GND. I put multimetar at "20k"
Measured Value is “1.15”

(I have psu from my mininova synth, 9V - 500mA wit center positive)
When i turn power, 2 leds are on and other light on touch.
On LCD i can se name and version but “ultra” dark, i only need
adjust contrast, but im afraid because heat rise fast and other components could get “burn” or damaged

One thing, when i measure for “beep” +5 and GND it is OK no "beep"
But when i turn power on, then is “beeping”

Overheating is "scary"
Here are pictures in big resolution.
I have 2 units wit same problem :frowning:
Thank you for help!

I connect audio out to speakers, midi keyboard to midi in and power.
IT WORKS! I hear notes from Shruthi but how much i try i cannot adjust contrast :((
I think it must be on 4PM mode in shruthi settings but i cannot come to that place without display…
Maybe it starts to reduce “heat” when is adjusted to 4PM???
2 ICs on filter board are burning and i notice that IC11 is 80% and IC12 20% i want to say IC11 is to
much warmer than IC12.
Any idea?

May be a stupid suggestion: have you ever tried another PSU? Something like a 7,5V? I have several PSUs that are labeled 9V but they put out almost 12V (with no load attached). Using one of these with the Shruthi also makes the power-regulators turn very, very hot very fast. Using the 7.5V they get warm but not finger-burning-hot.

Good idea! Thank you.
I measure my PSU from mininova synth, (9V -500mA) real value is 9.2V
At moment i don’t have another PSU wit centar positive.
What do you think about buying “universal PSU” it cost 8-9 €uros
Have switches for different voltage and connectors.

EXCELLENT! Tomorow im going to city and buy.

Your PSU is perfectly fine! No need to buy another one.
In your first post you wrote about smoke and smell coming from the display board: there is definitely your problem. Is the backlite of the LCD working? If not, then your backlite LEDs of your display are fried. And you need to find the reason for this.

I think you are right :frowning:

There was little smoke and smell only 2-3 seconds, i was thinking it was from “glue” from protection plastic…

My display is wit: Black background and Red characters)
When i turn power, front of display is BLACK nothing on screen.
Only light come from left and right side.
When i look from weird angle let say top i can se fonts but now i checked and is not English it look like random characters…
That is reason why i cant adjust contrast…
Now, i really don’t know what to do…