Ambika voice card issue. (narrowed it down to the main cpu but why?)

hi all. ive built an ambika obviously. my build is electrically the same as the stock version, but physically its very different. my issue is on the ambikas card spot #5 (port 5 A and 6A). initially all voices tested fine in the individual tests (all on voice 1 location), i proceeded with installation in their respective spots. all voice card shunts were set to their correct locations (A for first card- B for second card in the chain) . When powered up, data lights lit up on all cards. (#5 then became extremely din and both “data” and “note” were barely on. i immediately powered off. upon testing with the oscope and meter, all voltages are what they should be. (ALSO of note) #6 card (B card on the port) share the same connection in my format (not stackable headers, but twined 1 to 1 connection wires… that card was functioning correctly. so after testing all connections i chanced it. i put card 6 (b) int the 5 (A) position. it immediately did the same thing. a quick light up of “data” and “note lights then nothing and both dimley lit. i assumed the worst (the atmega IC) , so i extracted the atmega and put it into the 1(A) postion. expected result> non functional) . so is it possible there is a short somewhere (physically ) after the connection headers in the 5(A) position? (since 5 and 6 (A and B) share the same twined pairs of .10” connectors.) what would cause the atmega to short or lock up somehow?? all voltages into the cards are as spec’d. any help is appreciated i attached a pic of the physical format so you may understand better. all cards are on a frame. the frame is on standoffs as are the cards, and are in the stock, thru hole/mount positions. - thanks! shawn

Have you tried running the voicecard firmware update procedure to rewrite the firmware on those cards?

i have not as of yet…
im not sure what required to do firmware updates (hardware wise). ill look that up now and without a doubt look into doing that first now i guess. any ideas what would cause this issue in the cpu on the voice card? thanks for the hella-fast reply. wow!

You don’t need any special hardware.

Grab this file

Copy and rename it VOICE1.BIN, VOICE2.BIN … up to VOICE6.BIN. Copy it on the SD-card. Follow the procedure described in the manual:

“From the library page: Press S7 to display more commands: Press S3 to bring the about page:”

“The first half of the screen displays the version of the OS running on the motherboard. If a firmware update file named AMBIKA.BIN is present on the memory-card, pressing S1 (upgrade command) will load it to upgrade the main processor.”

“Ambika contains seven ports to which devices are attached. The first 6 ports (port 1 to port 6) are used for connecting the voicecards ; the last port (port 7) is used for connecting additional controllers or I/O connectors. The second half of the screen on the about page shows the device type and OS version number for a selected port. Use the encoder to scroll through the ports. When no device is attached to a port (or when the device firmware has been corrupted), a ‘?’ is shown in place of the device type. If a firmware update file named VOICE$.BIN (where $ is the port number) is present on the memory card, pressing S4 (upgrade command) will load it to upgrade the voicecard processor.”

Link to the manual.

wow. allright! that is totally doable. thank you it shall be so then…

well… ive put the voice firmware .bin files on the sd card now but ive encountered another issue- the sd card has stopped reading/writing. it was working correctly. i get the i/o error every time and have resoldered all connections (mine is extended/jumped with wire and 2.54 headers to the sd location (less than 6 inches away from mobo’s stock pcb mounting) … and tested continuity from the pads to the pins on the sd card enclosure itself. the weird thing that i encountered is- should the 3rd and 4th pins of the 8 (from the left - not by the smaller/unused pins ) have continuity between them from somewhere on the mobo pcb? when i tested between pins, i get continuity between those two pins? but if i unplug the connection header and test - its on the mobo side, not the sd card side. thanks for any help!

ive gotten the sd card functioning again ( the 4052s seemed to be slightly oxidized and needed reseated/cleaned) so i followed the instrunction per the steps in the manual. when i get to the upload os page for the voice … it seems my cards (port 5 and 6) arent recognized -since it says “install?” not “upgrade”. am i correct in assuming that theres something keeping hem from being recongized? a bad connection on the port lines maybe? thanks for the help pichenettes! ill check those next. upon getting to that page, i slected the lit key for “install” now i have a constant green light for the “note” led. ill check and re-solder all the physical connections for those 2 ports and try it all over again. (firmware upgrade/re flash)? any other advice?

> arent recognized -since it says “install?” not “upgrade”. am i correct in assuming that theres something keeping hem from being recongized

If the firmware is not installed and/or if the card has locked itself in firmware update mode, it will not be recognized, so this is consistent with the symptoms you described. What happens when you try the install?

when i click the switch under “install”, the other 4 "data " lights go out for about 3 seconds and then the voice card recieving the install’s “data” and “note” lights flash back and forth about 3 times. after that the note light is constantly on. but no response from the main cpu/ midi when assigning voices. thanks for any help!

One thing which is not clear if the problem is with the voicecards themselves, or with the fact that they are hooked to slots 5 and 6. Have you tried putting them to other slots to upgrade them?

i will try this today. info that could be of note though: when i noticed it was non functional in the 5 and 6 positions, i swapped it with number 2, it was not working there either (due to firmware brickup or mode status of cpu i assume) so when i swapped atmegas(leaving voice card 5 in position 2-but switching voice cpu’s ) it was 100%. is say with 90% assurace that the original issue is with 5 and 6 positions and then it became a voice card cpu issue. i will try and move it to a fuctional position and re-establish the firmware in that location ,and also re wire the 5 and 6 positions and check the voltages and data on those lines etc… thanks for the help pichenettes

pichenettes> ive re-installed the firmware and normal functions on the voice cards 5 &6. they worked flawlessly for the re -flash in position 2 . upon further testing: i put the cards into each position (5 and 6) and both did exactly the same thing as before…so i tested all theJP5 and JP6 lines to be sure that they read the same as the jp1-4 lines. ive noticed that the “SS4” line from the HC chip (pin one on jp6) isnt reading as the other 4 pins receiving the “ss” info from it. it should be roughly about 5 v and has barely above zero volts. im going to check the pins solder points on the pcb for the HC ic and then the pins on the ic itself. thank you for the info and help ALSO what is the function of the “SS4” line and would that cause the firmware lockup that is happening to both cards recieving that line? thank you so much!

The SS4 and SS5 line are SPI slave selection lines. They should be high all the time except when the MCU is sending a message to the voicecard 5 or the voicecard 6 (the MISO / MOSI / SCK lines are shared by all voicecards, so we need a way of telling which voicecard the message travelling on these lines is addressed to!).

If these lines are flaky/unstable, the voicecard will get random chops of messages not addressed to it. It is likely that in the long run, these random blocks of data will contain commands equivalent to “get in firmware update mode” or “erase this portion of firmware memory” etc (typewriters and monkeys…) The traffic on this bus is heavy and checksums/error corrections would have slowed transmissions (and thus LFO refresh rates, latency & all)!

Check that the A/B jumper is correctly set on voicecards 5 and 6.

Check that there is no adjacent solder blobs on the 74HC138 pins.

ive checked all physical possibilities and probed and metered it back to the pin of the hc itself. no voltage or visual display on scope or meter. i desoldered all connection and cleaned the vias/openings for the jp5 and 6 lines and tested for continuity between them. at pin 11 on the hc itself (not the chipseat) theres no voltage at ll i. im guessing its not functional at that pin. ive allready ordered a replacement from digikey to try this. im just about 100% certain from your descritption that this is the issue causing all the mess. :slight_smile: it should be here in 2 days. so hopefully that will be the needle in the haystack here. thanks for making the firmware upgrades able to be done with the sd card. thats engineering genius sir. my hat is off to you in 1000 ways! thanks for the help and ill replace the hc and see what happens.

sucess! all 6 fully functional voices! it was a the non functional pin 11 that was the
"ss4" line! replacing the 74hc138 mux/dmux was it! thank you for all the help! and the fantastic synth engine! its a monster. all the best pichenettes