MIDIBox SID voltage issues

Testing/Troubleshooting
1

I got my MIDIbox SID kit a few weeks ago, and went on a soldering frenzy. My lot of old C64’s finally showed up, and I found a c64 at a thrift store for $4! So, now I’m all stocked up on 6581’s and 8580’s.

So while I waited for the SID’s to show up, I built my JDM programmer, a Core module and a SID module.  The JDM, had low voltages, but I think that was because the Serial port on my laptop puts out a low Voltage. Needless, it programs the PICs. The core module came off without a hitch. When powered with a 9V -500mA wall wart, all the voltages check fine.

Next, my SID module seemed to have come together okay. After everything was completed, I hooked up a 15V - 1000mA wall wart to J1. I got 12V on pins 14 and 28 of IC1. Disconnected the power, and then wired up the Core module to the SID module. Those ribbon cables drive me batty! I need to find a place that sells custom connectors for those guys.

After connecting up the SID module, I powered the core with the 9V again. And I got 5V on IC1:25 - IC1:14,

IC2:16 - IC2:8, IC3:16 - IC3:8. Cool, everything seems fine. Disconnect the power, hooked up some midi Cables to the code, and an Audio jack to J3 on the SID.  Then, stuffed the IC sockets with a 6581 and the 2 registers.

Now here is where things go awfully wrong. Put 9V on the core and 15V on the SID. Open up MIDI-Ox to start programming the PIC, and I get no MIDI from the Core. I then go nuts thinking I wired up the MIDI connectors wrong, then I thought maybe my MIDI interface was screwing with me. Finally hours later I check the Voltages coming off the MIDI ports. It’s 1.4V. I check the Voltages on the Core on the PIC, and I’m getting 1.4V. I check the Pins on the SID board IC1:25 - IC1:14,

IC2:16 - IC2:8, IC3:16 - IC3:8. All 1.4 Volts. Also the SID makes a Heinous moan!

WTF?  ??? So, let’s start over. I disconnected everything. Now, powered up the core. 5V. everything is cool.  Now connect the MIDI. 5V. got MIDI-Ox going. Bang! I got MITI action. Programmed the OS, and Main SID app, and I see the thing boot up nicely now through MIDI. ;D

Now I hook up the SID module. Powered them both up. No MIDI. 1.4V again. Checked all my soldering, things look fine, I’ll have to check again though. But I didn’t see anything outwardly wrong. Did some continuity tests and everything seem okay. The Resistors are measuring the right resistance. WTF?  ???

So now I only connected the 5V of J10 on the core to the 5V pin on J2 on the SID. Okay now were getting 5 volts across the board, I have MIDI now too! Hook the rest of J10 back up. No go, only 1.4V. Back to just the 5V pin. Works. Now I hook up the ground pin on J10 on core to the ground pin on J2 to the SID. Now I’m getting 1.4V!

Reading, and reading, and rereading all the material on here, I can’t for the life of me figure out what is wrong? Why is it when I hook the core up to the SID with the ground giving me 1.4V? Is my SID fried? :stuck_out_tongue:  Am I doing something wacky with my power? Any help would be much worshiped here. ;D

2

Since no one else has answered, I’ll take a shot. It sounds like you have ground problems. Are you talking about using two separate power supplies - one 9v and one 15v ? I am not sure what you have to do if that is the case. Normally you would take the 15v and use the voltage regulators to get a 12v supply and a 5v volt supply. Hopefully someone smart can correct me if I’m wrong.

Justin

3

Wildly asymetric loading will cause a lot of DC wall warts to act up or shutdown when they share a ground rail.

Justin has it right, Try feeding the 15vdc supply into the unregulated power inputs on both the CORE and the SID.  If everything runs super hot this way, the 15v PS might not have enough current to run your box, if this is the case switch to a suitable transformer with AC output and your problems should go away… ; )

Best!

Smash

BTW no smarts here, just a few rowdy brain cells that still talk to each other through all the muck and my big mouth…  ;D

4

Okay, thanks for some tips. Sorry for getting back to this late, but here’s where I stand now. I went off and started making another SID board to see if maybe that one was bad.  This one had an 8580 instead, and the appropriate 9V regulator. Soldered it up, hooked it up, now powered the whole thing with a single 15V 1A DC wall wart (thanks for the tips on Power supplies). All the volages tested okay, and the MIOS I could see boot up. But now I have no sound coming out.

I had the midi I/O hooked up to my laptop, MIDI-Ox running, I can see all the bootup stuff happen. And then when I try to use MIDI-Ox keyboard to send notes, I get nothing from the SID. grrr… I also began to wornder if it had anything to do with the fact that I had the 6581 code on the pic and not the 8580 code.

After pouting for a moment, I loked at my previous SID board… Ah HAH! I had stuffed one of the register IC’s in backwards on the SID board. DOH! Put the register in correctly this time, and Hooked it back up to the CORE module, boot up, and the voltages are now working! yeah! But no Sound!

I’m thinking I need to hook up my LCD screen to see what’s goign on. I also tried to load the interconnect test, but I can’t seem to get it running.  I’m not sure If the BootStrap loaded it correctly, or if it’s even working. I send the modwheel messages, but the SID still seems to have 5V on all the pins regardless of what modwheel setting.

I also noticed that the 6581 was getting rather hot when it’s powered on. Are my SIDs damaged? Is there a way to test? I guess plunk it back into a working commodore and try getting a song to load huh.

hmmm. Well, when I comes to Electrical Current, I’m not that smart at all. I can say that I’m getting the hang of soldering, except for those damn SIL header pins. Need to find some IDC connectors.

Sean

5

Ahh. Nevermind… It turns out am pretty dumb!!  :-/

After posting that last message I went over and over again the schematics for the sids and so on. I also read up on some more posts. And then I realized that note on http://www.ucapps.de/mbhp/mbhp_sid_c64_psu.pdf  that said “was connected to J10:SC in the PIC16F based SID project”. I saw that so many times before and it didn’t quite sink in. I think I ignored i previously, because I thought that it only applied to using a C64 PSU. Then I looked more closely at the note, and I realized that the new PIC18Fs don’t have a 1:1 pinout on the interconnect.

Double DOH! :stuck_out_tongue:

Hooked it up last night, and after making many prayers to the gods of signal and feedback, the sid made sound! It made a glorious SID sound! So now my work seems to be coming to fruition. Time to start soldering up the rest of the boards and stop worrying (till i hit another dumb mistake!).

Sorry for the noise on this list, this stiff is new to me, so it’s taking a while for all the info on these sites to sink in.

Sean

6

Great Job Sean!

Don’t worry about making noise on the list. I would guess that at least 90% or more of the problems we post on the list end up being something dumb - usually a poor solder joint or short somewhere. Once you get experience, you can help out the next guy. And don’t forget to post some pictures or music when you are done!

Justin

7

Thanks guys. This MIDIbox stuff is great. And the community seems super supportive. I’m glad I decided to start building one.

Ohhh. And Smash, your PCB kits are awesome! I’m so glad I don’t have to bring all those crazy chemicals into my house.  Also, all the images and schematics on your site make things really super easy to layout all the parts.

Sean

8

;D