Ambika - LEDs firing but no audio :(

I recently sold my kit-built Ambika (single SMR-4 voice) to a guy in the US via the MuffWiggler forum.

Everything was working perfectly and it sounded great.
Only error was that I soldered the bi-colour LEDs in backwards.
(I’ve since learnt that Olivier added a software option to reverse the LED colours - very clever!)
Very securely packaged.

Ambika arrived safely, fires up fine, but it doesn’t appear to be producing any sound.
I advised the buyer:
Press S5 and make sure Mode is set Mono (default patch is Poly).
Press S6 and enable all voices on Part 1. You might have to disable some voices on Part 2 first.
That should basically be like a Unison mode.
He’s tried this, all the LP LEDs and the voice card’s LEDs light up as they should when Ambika is sent MIDI, but there’s no audio on the voice or master outputs.

The only “test” I can think of is to move the voice card to a different location or, perhaps simpler, move the shorting bar on the voice card’s headers from A to B.

If anybody could suggest a troubleshooting checklist given the problems I outlined above it would be most grateful.
Thanks in advance!

Sounds more like the buyer is doing something wrong… Maybe sending on wrong midi channel?

Maybe the jumper routing the voicecard to the audio bus is missing?

The plastic jumper that slots onto the voice card’s headers and selects between the A or B layers?
I guess that’s not an impossibility.
But it was working as it should before it was posted…
I’ll ask the buyer to send a photo if he can.

Are there any tests that can be performed to help diagnose the problem?

Thanks for your help, Olivier.

A classic one (and i am not joking here): if the owner is working on a console or DAW mixer, he should take a look for a muted subgroup or activated solo mode. Not that this ever happened to me…

We’re hoping it’s user error, but I think we may have ruled that out.
I don’t understand why there would be no audio when the voice card’s LEDs are indicating that it is receiving MIDI data and responding to it…

Maybe the TL072 on the MoBo popped out?

Try to eliminate all possible causes one by one. Does he have another audio source to test that the cable and whatever the Ambika is playing into are both working? If that is the case, is he using the correct channel for the voice output (it has to match the position of the voicecard), and is the volume pot turned up for the master channel? ,

I’ll ask him to take a look at this thread.

I think he’s eliminated the issue coming from simple stuff like MIDI channel, audio outputs and cables.

He sent a few photos of the voice card and both the headers on the pins are set to position A.

The TL072 is one possibility.
It would explain lack of audio, but he hasn’t reported any chips rattling around.

Any other suggestions at please before we have to consider opening the case?

Thanks again for the help so far.

The TL072 would explain no sound on the combo output but not on the individual output… I’d suggest opening the case and tracing the sound. Maybe first try to pick it up at the connector to determine if the fault is on the sound card or on the mobo, then trace one step at a time.

Juhu… This is my fourth “I make a working unit non working” story (Braids, Grids, Eurorack Tester, Ambika):

I sold my Ambika. I checked it before shipping and made sure everything was working fine. However I realized that a few leds were too high and that the lenses of the metal case weren’t sitting flat. I resoldered them.

… And now I don’t have any sound anymore. All the leds of the voice cards are lighting up, however I can’t hear anything. Neither on the main outputs nor on the individual outputs. Not even a slightly sound. It’s silent.

What could went wrong? I didn’t touch anything else. I only needed to remove two voice card stacks to get to the led solder joints.

Hmz :confused:

I think I’m on my way in destroying it more and more :frowning:

Check if you still have all voltages at their correct levels.

Okay, I don’t get the -8 and +8v (red/blue point) at the voice card headers. What could be wrong?

Remember, you need an AC PSU for Ambika. If you use a DC one then the machine fires up and looks to be working, but you get no sound.

I use an ac psu… It was working completely fine. I just wanted to fit the leds a bit better…

Check the voltage at the regulators see if they are getting very hot.
Also check the voltage of your PSU, put your meter in AC mode.

Okay, I used the wrong power supply :frowning: I had both connected to the same power multiplier and I was sure that the ac power supply was the only power supply with white cable… I was wrong… Argh, all the soldering and all the new bridges for nothing…

Golden rule number 1, always check the simple and obvious things first :wink:

I could also remove all the bridges that I added to find the failure. - It looks again like new… Puhh…
I think golden rule number 1 for me would be: DON’T Panic so fast…