nx1101 Posted November 7, 2012 Report Share Posted November 7, 2012 (edited) I have a strange issue with a sammichFM I recently acquired (I didn't build it). After a clean firmware installation, everything works as expected (as far as I can tell). As soon as I change a patch however, incoming MIDI notes start getting skipped by the synthesizer. The LED on the front panel lights up, but no audio output is produced. This continues to get worse and worse until only 1 out of every 10 or so notes is played, and then it finally stops producing audio altogether. Reading/writing patches still works, all of the menu navigation works, and LEDs light up on incoming MIDI, but no output. Powering on/off doesn't help. Resetting the firmware appears to help, though this may be coincidental. I'll add 1 more bit of info. Last night I reached the same zero-output state with only 1 audio cable plugged in (OUT1/2). Plugging in another cable (OUT3/4) appeared to fix the issue temporarily, but it eventually went back to producing no audio. Strange! I have a feeling it may have to do with cables I'm using. For each OUT socket, I'm using an insert cable (Y-cable, stereo 1/4" TRS to 2 mono 1/4" TS). Is that the proper cabling? Thanks for any help. EDIT: It appears reading/writing of patches is not working fully. Some recalled values are garbled. Edited November 7, 2012 by nx1101 Quote Link to comment Share on other sites More sharing options...
Sauraen Posted November 7, 2012 Report Share Posted November 7, 2012 A couple questions before I give a possible theory: - Can you play the first patch indefinitely long but once you change patches it starts getting worse? (It might be a problem with the BankSticks.) - Have you tried turning it off and unplugging it and letting it sit for a while and then trying it again (but not reinstalling the firmware)? - Have you tried any other cables? My guess is the cables are fine, but it sounds like some sort of power problem. Can you measure the voltage being output by the power supply while the synth is connected and running? If the voltage starts falling as it's running, that will degrade performance, and it may mean the power supply is bad or that there is some sort of partial short in the synth. It also could be a heat problem. Quote Link to comment Share on other sites More sharing options...
nx1101 Posted November 7, 2012 Author Report Share Posted November 7, 2012 (edited) A couple questions before I give a possible theory: - Can you play the first patch indefinitely long but once you change patches it starts getting worse? (It might be a problem with the BankSticks.) - Have you tried turning it off and unplugging it and letting it sit for a while and then trying it again (but not reinstalling the firmware)? - Have you tried any other cables? My guess is the cables are fine, but it sounds like some sort of power problem. Can you measure the voltage being output by the power supply while the synth is connected and running? If the voltage starts falling as it's running, that will degrade performance, and it may mean the power supply is bad or that there is some sort of partial short in the synth. It also could be a heat problem. Thanks for the reply, Sauraen. Yes, the first patch I use works mostly correctly, only a few skipped + incorrect notes. As soon as I switch banks things start to degrade quickly. Letting it sit powered off for a while does not seem to help. The same Y-cables and power supply work fine on a sammichSID so I think those are ok. I also tried using another power supply and got the same results. Is there any sort of diagnostic software I can run? Thanks! EDIT: See the EDIT in the original post. (Reading/writing patches isn't fully working as I'd thought.) Edited November 7, 2012 by nx1101 Quote Link to comment Share on other sites More sharing options...
Sauraen Posted November 8, 2012 Report Share Posted November 8, 2012 It now is sounding like a problem with the BankSticks. I would say try this: take out all the BankStick EEPROMs and try running the synth again. There probably won't be any patches for you to load (because there's no memory to load them from), but you might be able to make a patch using the controls. See if the symptoms come back. If they don't, put back the BankStick that was in slot 0 and try running it. If it still works, keep adding them back until you find one that makes it start failing, replace that one, and then install the firmware again (so it loads the patches into that one). Quote Link to comment Share on other sites More sharing options...
nx1101 Posted November 9, 2012 Author Report Share Posted November 9, 2012 (edited) It now is sounding like a problem with the BankSticks. I would say try this: take out all the BankStick EEPROMs and try running the synth again. There probably won't be any patches for you to load (because there's no memory to load them from), but you might be able to make a patch using the controls. See if the symptoms come back. If they don't, put back the BankStick that was in slot 0 and try running it. If it still works, keep adding them back until you find one that makes it start failing, replace that one, and then install the firmware again (so it loads the patches into that one). Hi Sauraen. I just gave that a try but the unit produced no audio output at all this time around. After reinserting the banksticks it still doesn't produce any output even if I reinstall the firmware! :wacko: Just to confirm I did this correctly, I removed the 5 components in the bottom left of this photo: http://i.imgur.com/qI91I.jpg and then inserted them one-by-one starting from IC5 up to IC9. Edited November 9, 2012 by nx1101 Quote Link to comment Share on other sites More sharing options...
Sauraen Posted November 9, 2012 Report Share Posted November 9, 2012 Yes, those were the right chips. Still on this same track of possible solutions, could you check for bad solder connections on their sockets? If you have extra BankStick chips, you might try those instead (but I wouldn't go ordering new ones except as a last thing to try). Also, I'm not specifically familiar with the sammichFM firmware, but probably when you just turn it on with no BankSticks it will not produce any sound because it has no patch, that's why I suggested you make a patch using the front panel and try playing that. But the fact that reinstalling everything didn't help makes me think it's a hardware thing. Another line of inquiry: When it was failing at first, did it seem to be skipping MIDI messages or was the sound itself failing? That is, the core writes to the OPL3 telling it to start and stop producing sound; if the core was dropping MIDI messages or there was anything wrong on the core side, you would tend to get notes stuck on or otherwise get sounds out of the OPL3 but not be able to properly control them. This question might help narrow down whether the problem is in the core/BankSticks/MIDI input or in the OPL3/YACs/amplifiers. Just to mention, there could be a power-related issue internal to the synth (e.g. some sort of partial short) that switching power supplies wouldn't fix. I might suggest looking over the board and testing with a multimeter any solder connections that look questionable. Also, have you tried running the synth without the front panel board on? (I'm not even sure if this is possible given the firmware, or if you have to press one or more buttons to get it into a playable state normally.) Quote Link to comment Share on other sites More sharing options...
latigid on Posted November 9, 2012 Report Share Posted November 9, 2012 With no bank stick inserted, the default Rhodes Piano patch is loaded, can you test this? Quote Link to comment Share on other sites More sharing options...
nx1101 Posted November 10, 2012 Author Report Share Posted November 10, 2012 With no bank stick inserted, the default Rhodes Piano patch is loaded, can you test this? Yes, when I removed all the banksticks, Rhodes Piano patch was loaded. No output though. Another line of inquiry: When it was failing at first, did it seem to be skipping MIDI messages or was the sound itself failing? That is, the core writes to the OPL3 telling it to start and stop producing sound; if the core was dropping MIDI messages or there was anything wrong on the core side, you would tend to get notes stuck on or otherwise get sounds out of the OPL3 but not be able to properly control them. This question might help narrow down whether the problem is in the core/BankSticks/MIDI input or in the OPL3/YACs/amplifiers. Good point. When I did get audio output, the sound itself was fine, so I think the OPL3 and amp circuit is intact. Just to mention, there could be a power-related issue internal to the synth (e.g. some sort of partial short) that switching power supplies wouldn't fix. I might suggest looking over the board and testing with a multimeter any solder connections that look questionable. I'm inexperienced in debugging circuits but I'll give this a shot. Also, have you tried running the synth without the front panel board on? (I'm not even sure if this is possible given the firmware, or if you have to press one or more buttons to get it into a playable state normally.) I did try this -- same results. Thank you so much for the help. Quote Link to comment Share on other sites More sharing options...
nx1101 Posted November 12, 2012 Author Report Share Posted November 12, 2012 Here's as hi-def a shot I can get of the solder joints: http://i.imgur.com/Eac7L.jpg I tested many of the joints with a multimeter -- not sure if my technique is correct -- and didn't find anything. Does anything jump out? Thanks! Quote Link to comment Share on other sites More sharing options...
latigid on Posted November 12, 2012 Report Share Posted November 12, 2012 It could be the light, but try touching up the joints on pins 15 and 16 of the DIL-40 socket. Preferably with the PIC removed! I will sound like nILS, but: offsite doco = bad! Please upload your pictures to the forum. Quote Link to comment Share on other sites More sharing options...
Sauraen Posted November 12, 2012 Report Share Posted November 12, 2012 Also maybe pin 6. As far as I can tell pins 15 and 16 are just connected to J6/7 which are not used here, but pin 6 is connected to the BankSticks. Quote Link to comment Share on other sites More sharing options...
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