SIDv2, MB6582, SSM2044, AOUT_NG Praise and a couple questions.

MIDIbox SID
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I finished my MB6582 just about a year ago and have been using it off and on since, I’ve always liked the synth. I have finally gotten around to getting an aout_ng and an ssm2044 board put together. I am just completely floored by how amazing this setup is. I have owned and had access to many synths over the years and this is right there at the very top of the list in my opinion. The only thing I have ever heard that was as ballsy as this setup is a mini. It’s increadibly warm and organic, it never tires my ears out. Before I just liked the synth, now I am fully in love.

I just wanted to say thanks again to TK, Wilba, Seppoman, and everyone else who has helped me and contributed to this project. You guys should be very very proud.

So now for a question. Somewhat recently I have been running into a problem. When I first turn on the synth often times it doesn’t start. The power led will light up, but not fully, its dim. Some times it will eventually turn itself on, but more often if I leave the power switch turned on and unplug the psu and replug it in to the power jack on the synth once or twice it will start up. I have taken some measurements when the power is on and the led is dim. I am only getting about 2v at any of the 5v pins on the base pcb. A lot of the time the synth will actually start up as a result of me taking a measurement. Once the pic boots up the readings are normal everywhere a nice solid 5v. Usually after I have been using the synth for a while it will turn off and on normally.

My first thoughts are that the psu is bad. Its an original c64 psu that supplies 9v and 5v. This could very well be the problem, but when I take a measurement from the pins on the power jack I’m getting around 5v usually a little higher, but still only getting around 2v on any of the 5v pins. I’ve looked for shorts and re-flowed most of the solder joints, that’s not to say I didn’t miss something. Any suggestions on what I should replace first or where I should look?

Second question. I would like to use one of the cores on the base pcb to run a different application some of the time. I have an app that does some midi processing for my ESX, and it would be cool if I could use one of the cores to do this when I don’t need it as a SID engine. So can I just upload the hex to the core I want to use? I know there is only one optocuplor and one set of midi io, would it be possible to use an IIC module to get a set of midi io to one of the slave cores and still have the main midi io for the other 3 cores?

Thanks again,

Luke

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Maybe your PS is sagging under load?

I had one that would sometimes work, sometime not.

When you measure it directly (under no load) it’ll show 5v+ ?

But when you measure it while plugged into your 6582 it’s showing less?

my $0.02

Regards

Mike

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I agree, sounds like the brick is sagging under load. You could try removing SIDs and see if the problem happens less often, that would prove it’s a current load problem.

Second question. I would like to use one of the cores on the base pcb to run a different application some of the time. I have an app that does some midi processing for my ESX, and it would be cool if I could use one of the cores to do this when I don’t need it as a SID engine. So can I just upload the hex to the core I want to use? I know there is only one optocuplor and one set of midi io, would it be possible to use an IIC module to get a set of midi io to one of the slave cores and still have the main midi io for the other 3 cores?

That’s certainly possible. Perhaps you don’t need an IIC module. All the PICs share a common MIDI In (i.e. RX pin of PIC) but you could cut the track to the 4th PIC. The TX and RX pins are available as a 2-pin header, so if you want to reconnect it as per the MB-6582 PCB, you just connect the RX pins again with wire. Then just put the same MIDI In/Out circuit as you’d find on a Core PCB - i.e. the optocoupler and 220 Ohm resistors… these could fit behind whatever MIDI sockets you use, so you only need 5V/TX/RX/Gnd connected to the 4th PIC. While the CAN bus between all the PICs would still be connected, I don’t think that would be a problem if CAN is not being used by the app… but it’s probably best to only use PIC18F4685 in that socket since there’s a diode bridging pins which are used for LCD output in other PIC types.

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btw are you connecting the MB-6582 to AOUT_NG via the expansion port? Maybe there are spare pins for this extra MIDI channel… female 5-pin DIN plugs are easily available.

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Maybe your PS is sagging under load?

I had one that would sometimes work, sometime not.

When you measure it directly (under no load) it’ll show 5v+ ?

But when you measure it while plugged into your 6582 it’s showing less?

The psu seems to always show +5v, that’s the weird part. Even when the base pcb is showing +2v, the pins of the psu are showing +5v. So I think something is going bad on the base pcb, but I’m not sure. I have a desktop power supply that I’m going to try to see if its the psu before I do anything to the MB. Another weird thing is that once it starts, it never flakes out on me. Works just fine. It’s only an issue when first starting the synth. Think it could be a bad cap or something maybe?

I agree, sounds like the brick is sagging under load. You could try removing SIDs and see if the problem happens less often, that would prove it’s a current load problem.

I tried removing all pics and sids except on core one and I got the same kinda behavior as far as I could tell. But I will certainly try that again. What makes it kinda tricky to debug is that once I’ve been using it for a while the problem seems to go away. I will try using my bench supply to eliminate that as a possibility.

Then just put the same MIDI In/Out circuit as you’d find on a Core PCB - i.e. the optocoupler and 220 Ohm resistors… these could fit behind whatever MIDI sockets you use, so you only need 5V/TX/RX/Gnd connected to the 4th PIC.

This is great news, I was originally hoping I could just use the included midi io but wasn’t sure I would be able to since there are no pins for it on the pcb. I will give this a shot over the weekend.

btw are you connecting the MB-6582 to AOUT_NG via the expansion port? Maybe there are spare pins for this extra MIDI channel… female 5-pin DIN plugs are easily available.

Yes it is, and this is exactly what I had hope to be able to do. I am currently working building an additional enclosure that has the same width and height dimension as the pt10 case but thinner and not slanted so I can sit the MB6582 on top of it and just connect it via the expansion port.

but it’s probably best to only use PIC18F4685 in that socket since there’s a diode bridging pins which are used for LCD output in other PIC types.

The application that I wrote for the ESX is currently running on a 4685, so this should work out perfectly. I’ll give a shot and let you all know how it goes. I’m sure I’ll run into something I’ll need help with.

Thanks,

Luke

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This is great news, I was originally hoping I could just use the included midi io but wasn’t sure I would be able to since there are no pins for it on the pcb. I will give this a shot over the weekend.

It’s J11_COREx. It aligns with PIC pins, so left pin is TX, right pin is RX. You can cut the RX track on the bottom layer track between the pin and the via. Convenience!

Yes it is, and this is exactly what I had hope to be able to do. I am currently working building an additional enclosure that has the same width and height dimension as the pt10 case but thinner and not slanted so I can sit the MB6582 on top of it and just connect it via the expansion port.

Yeah something like that is on my todo list… I need to box my SSM filters in something other than a shoebox :slight_smile: