SD Card Problems with new Ambika Build

I can’t figure this one out.

No SD cards will work with my Ambika. I’ve tried 3 brands and a real Sandisk.
Presets all come up (empty) and it won’t load a firmware update.

HOWEVER: It will load the firmware when I use the emergency boot mode! (holding down S8 to load from SD card)

So what’s the difference between the emergency SD card boot and normal SD card access? I’ve tried a different CD4050 but no luck.

Any ideas?



Is the card formatted correctly?


As far as I know yes. A new card out of the package did not work, reformatted to FAT32 did not work, all the other cards reformatted to FAT32 had the same errors. I’m Copying the MULTI and PROGRAM folders directly to the root of the card.

I’ve built an ambika before that had card errors but buying a real Sandisk solved that one. THIS one is a headscratcher!

Have you tried reflowing the solder on the card slot contacts?

Failing that, try following the tracks back from the card slot to the ATMega MCU, and check for bad solder joints on any components along the way.


Reflowed all joints between Card, CD4050, MCU and 74HC138. All buzzed out fine before and after. 3.3v regulator shows fine voltage.

I think the clue as to what is going on has got to be in the weirdness around the SD card load. It works on emergency boot to load the firmware but doesn’t work for presets. Somehow.

could be wrong though. And thanks for your help toneburst!

Pretty sure now that it is the 74HC138. All voices are now unrecognized and ? for all devices in the update menu.

Gonna pop a new one in there once it comes in and update this but if anyone knows of anything that matches these symptoms please advise!


I remember some talk about that IC here on the forum when the Ambika was first released.

Some versions of the chip were reported then as not working, but I don’t know if that was ever documented in the build docs.

You might want to do a search of the forum.

Sorry, I’d forgotten this before.


There were some problems with the CD4050 being to slow. You might try using a 74HC4050 instead.

It was the 4050, thanks all!