I have a problem that i don’t get any sound out of my sid, i only get a slight hum (ground?)
As i am a complete electronics noob i have no idea where to look for the problem.
All the voltages have been checked and they are correct, i have used a c64 psu.
MIOS and the testtone have been uploaded succesfully.
here is a picture of the pcb (large pic)
The testtone application has a special feature which allows you to test the output amplifier without SID.
Power Off your MIDIbox, unplug the SID, apply power again and connect pin #8 of the socket with pin #27. Do you hear a 1 kHz pulse sound thereafter?
Best Regards, Thorsten.
i tried it, i heard a low buzzy tone.
then i disconnected the pins and tried again and then i didn’t hear the tone anymore.
Also, the hum is gone with the SID out of the socket.
hello
are you sure your 74hc595 are good ? i’m not sure it can help.
Is there any way to test them? or do i have to buy a new pair?
The 74HC595s can be tested with the mbsid_interconnection_test application. See the README for details about the test procedure.
Best Regards, Thorsten.
Hi, I killed one 74hc595 by placing it backwards on the MB6582 (or it was dead before, who knows :D) nd of course I got no sid sounds from that channel, check if yours are placed correctly/try using new ones.
The 74HC595s can be tested with the mbsid_interconnection_test application. See the README for details about the test procedure.
Best Regards, Thorsten.
All give correct voltages (5.04V). So that means they work, right?
Yes - so it seems that your SID isn’t working.
From where did you get it? Are you able to test it on an old C64?
Best Regards, Thorsten.
I tested my SID in the c64 i cannibalized it from using poke commands, and it works in the c64.
Ok, last possibility: measure the voltage between pin #14 and #24 #28 when the SID is plugged in. For a 6581 it should be 12V
Best Regards, Thorsten.
i get 0.01V on my 6581
Obviously there’s a problem with the supply, eh? 
SIDs don’t run w/o power. What PSU are you using?
c64 psu, but i get 12v on pin 28 and 14 with or without the SID inserted, so the psu most work? ???
That’s correct actually pin #24 is potx and I am not sure about what voltage it should/could have. 14 Vss - 28 Vdd should be 12V as you measured.
Check your soldering. Better yet - post pictures.
You are right… pin #28 was the intended one.
To summarize: you’ve checked the SID itself, the amplifier, the control signals between 74HC595 and SID, the 5V/12V supply voltage - so: almost all pins, and they are ok.
Remaining pins are #1..#4 (caps) can only be checked visually (should be easy!)
Pin #6 (the clock pin) is connected to CORE::J10:PWM. On the core, it’s a routed to Pin #17 of the PIC. Depending on the PCB you are using, a cable is required as a bridge (see also this picture - the red marked connection) - did you consider this?
/Edit: a better picture
Best Regards, Thorsten.
Yes! it works, i had the short red cable at bottom connected to the wrong pin.
It works great, i only hear the tone going really silent when i let go off a key.
Thank you.
The low sound isn’t much hearable when recording it luckily.
Gonna be a long night fiddling with my new toy 
Thank you very much for the help!
If you ground the input to the SID, the background noise will drop even further..
