Grimbert Posted March 29, 2009 Report Posted March 29, 2009 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)http://www.elexorien.com/bla/pcb.jpg Quote
TK. Posted March 29, 2009 Report Posted March 29, 2009 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. Quote
Grimbert Posted March 29, 2009 Author Report Posted March 29, 2009 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. Quote
reboot Posted March 29, 2009 Report Posted March 29, 2009 helloare you sure your 74hc595 are good ? i'm not sure it can help. Quote
Grimbert Posted March 29, 2009 Author Report Posted March 29, 2009 Is there any way to test them? or do i have to buy a new pair? Quote
TK. Posted March 29, 2009 Report Posted March 29, 2009 The 74HC595s can be tested with the mbsid_interconnection_test application. See the README for details about the test procedure.Best Regards, Thorsten. Quote
sineSurfer Posted March 29, 2009 Report Posted March 29, 2009 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. Quote
Grimbert Posted March 30, 2009 Author Report Posted March 30, 2009 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? Quote
TK. Posted March 30, 2009 Report Posted March 30, 2009 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. Quote
Grimbert Posted March 30, 2009 Author Report Posted March 30, 2009 I tested my SID in the c64 i cannibalized it from using poke commands, and it works in the c64. Quote
TK. Posted March 30, 2009 Report Posted March 30, 2009 Ok, last possibility: measure the voltage between pin #14 and #24 #28 when the SID is plugged in. For a 6581 it should be 12VBest Regards, Thorsten. Quote
nILS Posted March 30, 2009 Report Posted March 30, 2009 Obviously there's a problem with the supply, eh? ;) SIDs don't run w/o power. What PSU are you using? Quote
Grimbert Posted March 30, 2009 Author Report Posted March 30, 2009 c64 psu, but i get 12v on pin 28 and 14 with or without the SID inserted, so the psu most work? ??? Quote
nILS Posted March 30, 2009 Report Posted March 30, 2009 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. Quote
TK. Posted March 30, 2009 Report Posted March 30, 2009 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 pictureBest Regards, Thorsten. Quote
Grimbert Posted March 30, 2009 Author Report Posted March 30, 2009 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. Quote
Grimbert Posted March 30, 2009 Author Report Posted March 30, 2009 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! Quote
Futureman Posted March 30, 2009 Report Posted March 30, 2009 If you ground the input to the SID, the background noise will drop even further.. Quote
Grimbert Posted March 30, 2009 Author Report Posted March 30, 2009 Do you mean shorting J4 (Audio in) ? Quote
Futureman Posted March 30, 2009 Report Posted March 30, 2009 Do you mean shorting J4 (Audio in) ?I'm not sure (From memory) which J it is, but yes, the audio input shorted to ground.When I read this, I thought.. oh.. how much could it drop it, but it drops the background noise HEAPS..This does depend on what SID you are using, but my 6582's dropped from about 7% noise to about 1% noise. Quote
Grimbert Posted April 1, 2009 Author Report Posted April 1, 2009 Yeah, it helps a bit on my 6581 too :) But it isn't noticeable when mixed together with other sounds, so it doesn't matter. Quote
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