Blank Screen With all the LED's Lit up

Just having some issues with the finalization of the assembly for the Shruthi-1. The Shruthi-1 does turn on, I am thinking that it’s the main IC chip on the control board. I did get it to say “mut” on the screen and different leds lighting up… but now blank screen with all leds lighting up. Is there anyone who knows what maybe the matter? Thanks!

Well I have the SMR-4 mkII board, and all the LEDS are lit up! I’ll check it out though. Thanks!

did your control board enter in contact with the filter board?

What would that do?

If the metal tab of the negative regulator touches one of the chips of the digital control board (can happen with the 4PM board), the chip scanning the switches can get fried, in which case the Shruthi-1 boots in firmware update mode (blank screen, leds 1, 3, 5, 7 lit).

Hi, I am working on this board with Krpticsnds. There are no exposed contacts above the regulators, but it is possible that they did touch, but not while powered up. Only ever gave the board power when it was fully connected together. I was thinking that maybe it went into boot mode, but from the forums 1,3,5,7 led light up. Not all of them. It was responding to button pushes for a while. Pushing SW1 and then SW2 and others would cause the led’s to light up in order, but then stopped doing that and just light up, then after a bit and with another button push, they would all turn off. The contrast was able to be adjusted because of the word ‘mut’ showing up on the screen for a while. The only variation I did to the plans was getting a 68 ohm resistor (which was what was spec for on the board and plans) because there was only a 3.3 ohm provided. I did find that there was a resistor switch up in the kit, from the forums… something about a different screen… but as far as I can tell, it would of only affect the brightness of the screen. Nothing else. It feels like the AT chip on the controller board is acting up. There is proper power getting everywhere, and I triple checked my solder points. I will post pics if requested. Kind of frustrating. Wanted to play around with it :frowning:

The 3.3 ohm resistor is correct for the LCD you woulda received with the kit, the 68 ohm was specified for an older LCD and will just make the backlight dimmer, no change to performance. Can you get a sound out of it if you send a MIDI signal on Channel 1 to the Shruthi? Also-try spinning the rotary encoder clockwise just after poweron-if that gets the leds lighting up in sequence then the MCU is probably OK. Recheck all the soldering to the LCD, both at the board and the module, as that could be a culprit.

There is no sound coming out of the Shruthi when I send MIDI signal. I checked my MIDI cable and it works. Tried spinning the rotary encoder clockwise just after powering up, but nothing changed. All LED’s are lit up and when I push one switch (any button) they all turn off. The dial doesn’t do anything. Checked all the LCD solders with a multimeter and visual: Found no issues. The top line of the lcd screen is filled (all the pixels are on) and the bottom is off (pixels are off).
As an extra, I did the trouble shooting suggestion for the filter board (MKii), and all things checked out when I put signal into the board except for 5,6,7,8. But I suspect it is because the filter board is not getting information from the control board… correct?

Your filter board checks are strange, because what you hear on points 5 and 6 shouldn’t be very different from what you hear on point 4 (it’s just further filtered, but if you have signal in 4, you must have signal at point 5 and 6).

If you think your ATMega chip is damage, you can send it back to me and I’ll check it.

Well I got the unit back from my good chum Gamma-ray. I’d thought I’d upload some photos and a video to hopefully help shed some light on the situation. If there is anybody in Vancouver BC, Canada that does repairs and would like to meet up to give me a helping hand I’ll buy you beer and your time will be much appreciated! :smiley:
As for my observations. When I plug power into my Shruthi all led’s light up, after leaving it on, with out fiddling about with the unit, LED 3 and LED 7 stay lit, while all other LEDs are off. The LCD Screen on initial power up has one row of (for lack of a better word) white blocks, which take up the very top of the screen. When LED 3 and LED 7 stay lit, then both rows of the LCD screen are occupied by white blocks. I apologize if this is convoluted. But you’ll see in the photos! Does this look like maybe a problem with the ATMega chip?
Picture Album (only three pictures. I apologize for the one blurry one. if you feel that more is need let me know what you want to see!)

It’s normal for all LEDs to be lit for a short time. LED 3 and LED 7 lit looks like a good sign - this is what you should get on a working unit anyway. Do the unit respond to key presses when it is in this state? If the LCD shows two lines, it’s also a good sign, since it has received the initialization command. Have you tried adjusting the contrast trimmer to reveal the two lines of text?

Right now the LCD is just showing ‘m’ which is progress. But the unit isn’t responding to any key presses. ad LED 3 And LED 7 are still lit. Thanks for getting back so quickly!

The ‘m’ is now gone after i disconnected power, and reconnected it. the trimmer doesn’t seem to be adjusting the contrast.

How long does it take for LED 3 and LED 7 to show up? it looks as if the unit is booting, but at a terribly low speed, hinting at a problem with the quartz…

It seems to be taking a while. Well over a minute. like a minute and a half.

Check the quartz and the two capacitors around it. Maybe you’ve made a mistake there and the quartz is oscillating slowwwwwwly?

Could it be fuses programming issue resulting in MCU running at default 8MHz instead of 20MHz? The start up LED’s blink seems to be twice the time it normally takes.

I had that with the MIDIPal when flashing it, very slow. I’d not set the fuses right.

She works! Today Gamma-Ray and I dove into the Shruthi-1 and we fixed the issue. It was a backwards electrolytic cap. Which, makes me feel dumb :frowning: However She is fixed now and Roaring! thanks for all your help guys

Well It looks like I may have jumped the gun! For two days my Shruthi-1 was working. It was sounding fat it is for sure my favorite synth. There is magic that happens with those 8 bit chips and analogue filter board drool. I left her on for the most part yesterday as I was composing a piece for a theatre show I’ve been commissioned to do. After a while the shruthi would freeze up. which is okay I just unplugged it and plugged it back in. After this happening more then once I took it apart and looked at the solder points, they looked fine, I switched the midi preferences to just midi out. When that didn’t work I switched it to cntrl, still freezing. I searched the forum and found some very valuable information, regarding another resistor. This morning, I plugged my Shruthi-1 in and now I’m getting a blank screen with led 3 and 7 lit up. After a few more attempts of unplugging and re pluggin I did get the Mutable Instruments splash screen, But now parameters are changing values by them selves. No midi is plugged in, just the power supply. very odd. When i did see this has stopped I plugged my midi keyboard in and noticed that a lot of the notes on my keyboard are playing the same notes. Also very odd. I’m a bit perplexed and a tad overwhelmed. Any help would be much appreciated!