HELP : problem at boot : all LEDs stay ON

hi !
well, i just finished to build my shruthi (with smr-4 filter board) but have some problem…
so my problem is clear : when I power on the shruthi-1, all LED are ON, (only 3 and 7 should be ON … ) nothing changes if I play with buttons…

help please :frowning:

Maybe you put the 74HC595 (left small chip on the frontside) upside down? If not, check if PIN 14 of the 595 (Right side 3rd from top, seen from above) is permanently on +5V, mybe you have shortened a line to Vcc…

it seems that the 595 is in the right position (exactly as in the picture in assembly instructions…)

but i dont have +5V on PIN 14… only something between 0.01 or 0.03 V … what should I check ?
(i’ve checked the +5V coming from the filter board on the control board, but i only have 4.07 V … is this normal ? )

thanks for the help !

Having not +5V on Pin 14 is good.

4.07V is to low, what kind of wallwart are you using (less then 7,5V 500mA) ? Have a look at the Power Supply Caps, are the damaged (round head). Do you still read +5V when the Digital Board is not attached?

i have a 9V -1A wallwart.
if i remove the control board, then i have correct + 5V output on filter board…

All other chips in the right position/heading? Theres not much that can go wrong on the digital board… LCD correctly soldered? Backlighting on? What do you read if you remove the ATmega, eEprom and Optocoupler?

i haven’t soldered the LCD yet… but as far as I understood, it should work without it…

well, i’ll double check all chips again…

all chips position seems OK.

I’ve tried first to remove eEprom and Optocoupler, nothing changes…

Then I’ve put them back and removed the ATmega : now I have correct 5V instead of 4.07V (with all LEDs OFF)…

Hm. Every Pin checked, no bend Pins? If so it seems its dead…

all pins are looking good… so this could mean that my ATmega is dead ? ho no… :frowning: and i cant even order a new one, there’s no more in stock… :frowning:

@aslak: please send me back the chip, I’ll check it and send it back to you, or offer you a replacement at catalog price. I have half a dozen in stock.

However, I had someone else’ board here two days ago ; the problem was a dead ATMega (the first time I have observed this!) and the voltage readings were correct ; so this might be something else…

@pichenettes: ok, great, thank you :slight_smile: i’ll ship it as soon as i can. Thank you for the support !

but by the way… During assembly, I did some not pretty “soldering / unsoldering / resoldering” with the two IC Sockets DIP 8… and I’m affraid that I maybe damaged the PCB … I made lots of checks, and found this which seems anormal :

  • I checked the 4 pots : GND and VCC are OK. but the center PIN goes like this :

on pot 1 -> ATmeg PIN 40 (correct)
on pot 2 -> GND (wrong)
on pot 3 -> GND (wrong)
on pot 4 -> GND (wrong)

  • so i checked the PINs ont the ATmega :

PIN 40 -> pot 1 (correct)
PIN 39 -> GND (wrong)
PIN 38 -> nothing (wrong)
PIN 37 -> GND (wrong)
PIN 36 -> cv in 1 (correct)
PIN 35 -> cv in 2 (correct)
PIN 34 -> cv in 3 (correct)
PIN 33 -> cv in 4 (correct)

I’ve made several others checks, but all the rest seems ok…

First question : am I right with my “correct/wrong” comments ?
Do you think I have damaged the wiring inside the PCB ?

thanks again for you help and support ! it’s really appreciated :slight_smile:

I am not sure what you are testing (continuity or voltage)… Also, this depends on the position of the pot! If it is turned left, it is shorted with GND, if it is turned 100% right, it is shorted with +5V. So put them at the middle position and check:

  • That there’s no continuity between the wiper (middle pin) of the pots and GND and +5V.
  • That there’s continuity between the wiper of each pot and the pins 40, 39, 38, 37 of the ATmega (or the socket).
  • With the board powered, check that the voltage on each wiper is 2.5V

hehe :slight_smile: right… i forgot about the pots… (i was only testing continuity) sorry, i’m a bit a newbie… I’ve often done simple electronics soldering at school or at my job, but it’s the first time i build a kit like this…

so i made all the checks you said :
everything is OK exept continuity between the wiper on pot 3 and PIN 38 on ATMega socket… (i guess this is due to the damages on PCB around IC4 socket i was talking before… but still doesnt explain the 4V voltage/boot problem…)

@pichenettes: ok, i’ve just sent the chip this morning. You should recieve it still this week.