Ambika lives! She's not much for words though (SMR4 voice card troubleshoot)

It’s alive! I got my AC adapter in the mail this evening and immediately tried to power on my Ambika for the first time. Very snazzy!

The motherboard seems to be fine, all the lights come on and all the knobs and switches work. My issue seems to be related to the SMR4 voice card.

First thing I did was disable all the other VC slots and only turn on card #1. I loaded up a patch, connected a MIDI device and plugged in my headphones to the main output. No sound plays when I fiddle with the MIDI keyboard.

Biggest give away to there being a problem is that no lights on the SMR4 illuminate when I’m playing notes. I couldn’t find any voltage troubleshooting instructions on the DIY resources, so I’m not sure where to start with diagnosing the issue. I did notice that the pins don’t fully slide into the voice card port. I tried using a shorter spacer, but the gap remained.

Below are a few pictures of the card. I can take some brighter pics of the solder points if need be. I’m hoping the problem is a simple fix I overlooked. Meanwhile I’ll try retouching some solder points, but they all look pretty tight with no shorts. Thanks guys!

EDIT: I tried plugging the card into the other voice card slots. Still nothing :confused:

Even without testing the sound and sending note, when a voicecard is correctly receiving data from the motherboard, the orange LED lights up.

Do you have +5V on pin 1 of the MCP4822? If so, the board gets power for its digital section and you should at least get the LED to light up. Have you tested the SD card? If it doesn’t work, it might also point to a problem with the 74hc138 - which will also impact the voicecards.

Best thing to do is to monitor pins 17, 18, 19 of the 328p if you have a scope.

I had the same behavior on my first voicecard, it was because I had inverted the 20p and 220n caps.

SD card seems to work properly. Was able to load different patches without a problem. I tried playing around with a few more parameters of the sound but still didn’t seem to get any audio output or visual feedback from the card LEDs.

MCP 4822 pin 1 on the voicecard reads a +5v. Pins on the MEGA 328p give me about the same readings (4.95v on the pins receiving voltage, one pin (29?) gave.60v). I traced some of the important IC pins from the diagram too and all the other chips on the board give about +8v or -8v (give or take .15v) depending on which IC it is. I’m wary of taking any jumpers off the board based on warnings about adding/removing voice cards when the Ambika is on, though I doubt jumpers have anything to do with this. D1 gets -3.75v.

The capacitor at C4, C10 has 101 on it and C26, C27 has IIC 224 on it. I remember getting to this point during the build and testing the 22pf caps to be sure which was going where. Those caps tested at 18pf, but I read in another thread this wasn’t much of a problem.

No scope handy unfortunately.

EDIT: Hmm, the SD card appears to be empty now for some reason. When I plug it into my laptop to check the contents the card doesn’t mount. Would tracing points have cause the SD to corrupt?

Touched up a few solder points this evening. Still no signs of life :frowning:

Not much you can do without a scope - it will be hard to tell whether the ATMega328p is alive… You could try reformatting the SD card, copying the voicecard firmware file there and try to do a voicecard firmware reinstall.

Alright, found another SD card I can use for now. Going to return the other one.

Also was able to pick up a scope from a hobby store today. Checked the pins you mentioned and I am definitely getting signal on those pins you mentioned. One of them (18 I think) looks like a stable waveform. The other pins gave a solid line with a little wavyness on it. Filters perhaps? I don’t really know what it means other than the 328p is working.

Where can I find these voicecard .bin files?

ambika_voicecard.bin - rename it VOICE1.BIN and try to run the voicecard firmware upgrade procedure for voice 1 (if this is the slot in which you have a voicecard inserted).

Nothing proves that the 328p is working at the moment - the signals you see are sent from the motherboard.

What do you see on pin 3 of the DAC?

Alrighty, so I tried doing a controller firmware upgrade first and that worked as expected. Tried the voice card firmware as described and i get a prompt at the about screen to install firmware to the port 1 device, but clicking install doesn’t seem to start any data transfer.

MCP4822 pin 3 doesn’t give any signal using the oscilloscope.

Do you have an AVR ISP programmer?

@portervance, seeing your pictures i’m almost certain that it is the same problems as me, as i mentionned on my previous post, you have inverted the c22 & c14 ceramic caps with the c22 & c27, i had the same behaviors all the same, no sound, just the install message etc etc.

the caps that you must soldered on the c22 and c27 emplacements are more round more ‘fatty’ than the others.

you can compare your own voicecard with the one built by nordlead voicecard pic
this is how i found out my mistake. Mine was built like yours: my voicecard with inverted caps

i made this mistake because of the 18pF capacitators that came with the kit instead of the 22pF written on the PCB, so i tried my own “logic”, and following my instinct i have inverted the capacitors.

@untoldb can you confirm the writing on the side of those caps? I had some trouble researching those two parts, yet they kind of look the same to me. From an earlier comment:

“The capacitor at C4, C10 has 101 on it and C26, C27 has IIC 224 on it. I remember getting to this point during the build and testing the 22pf caps to be sure which was going where. Those caps tested at 18pf, but I read in another thread this wasn’t much of a problem”

What are the IDs on the sides of your caps and what spots did you place them in? I’m brave and am willing to resolder but want to make sure it’s necessary first.

@pichenettes no avr programmer unfortunately :confused:

Thanks for the assistance guys! Hope I can make my Ambika sing pretty soon

forget it, i thought it’s about Anushri

My c26 & c27 ceramic caps are labeled 180, c14 & c22 are labeled 224. Hope it helps

C26,C27: is 22pF, should have 220 on it and be small ceramic.
what you have is 220nF, check C14 and C22, they should be 220N

C4,C10: 101= 100pF= correct

The ones coming with the kit for the c26 c27 are 180 but it’s ok according to olivier

Hmmmmmmm, ok.

Caps on my board are as follows:

C14, C22 (220n) = 180 written on the side
C26, C27 (20p) = IIC 224 written on the side

Looks like untoldlb was right all along :). I’m going to resolder those right now and see what materializes.

On a seperate note:

@pichenettes: I’d like to contribute to the documentation for building these cards, try to bring the instructions up to the level of detail for the Anushri kit. Can I send that to you via email? Maybe this documentation has already been in the works?

@portervance: I don’t intend to provide step by step assembly instructions for the moment. This will lower the barrier to entry to people who will get very frustrated a few steps later anyway, at the next big stumbling block (sourcing their own parts… troubleshooting…).

I’d rather see people educate themselves on a simpler project (Shruthi, Anushri), and then move to the Ambika once they have a better understanding of what they are doing.