Motherboard woes, LEDs and Switches don't work

Discontinued products Ambika
#1

Hi, sorry for my first post here being a call for help :frowning: But I have read every thread I could find on here about motherboard issues.

After some more fiddling today, I am at a loss with my Ambika. It is very slow to boot and the screen has sluggish response to knob parameter changes. Switches and LEDs don’t work, and my encoder doesn’t register left or right turns, only button presses. Navigation is stuck on the filter page.

Have tried:

Checking continuity between MCU and 165, 595s and also to encoder. All seems good.
Reflowed all the relevant joints.
Checked Resistor network orientation.
Replaced 74HC165, 74HC595s, xtal and caps.
Loaded firmware and set fuses again, seems to go smoothly with no issues.
All voice cards light up and seem to be receiving data from the MCU.

Hoping someone can help point me in the right direction, I imagine the LEDs and Switches not working could be related. Not sure what is causing the slow screen updating.

#2

Well I feel a little stupid, it was a programming issue all along. I think it was related to the fuses being overwritten or something. I was using a graphical UI for AVRdude called Bitburner, I think this was messing with the fuses.

I also found that with the version of AVRdude I have on Windows needs “” marks around the flash and eeprom writing commands. For ex: “flash:w:ambika_voicecard.hex:i”.

Anyways, it all works now. On to tuning.

#3

Nice to hear that you finally got it sorted, and thanks for sharing the knowledge. The symptoms surely seemed to indicate the wrong fuses (causing too slow MCU).
Cheers

#4

I had that when I programmed my MIDIPal once, always a relief that it’s not a hardware issue.