How can you tell when your SID is dead?

[Flecko]

I hate to say it guys, but I think I may have blown my SID before it squeaked its first sound. I have the address/data latching correctly, so I need to ask a question now.

What is the minimal set of writes you must do to make ANY sound come out of the SID? I've tried sending what I think should be the right set up to the SID, and made sure the VOL was turned up, but still nothing is coming out. I've got all my connections right now(oops...put a PNP on the output instead of an NPN  ???) so it should be working. I even tried hooking the output directly up to an oscope, and it only hiccups when I write to the SID, otherwise, silence.

If anyone can help, I'd appreciate it. Also, in the worst case, where can I get a cheap SID chip(6581 preferrably)? I looked on ebay, but no luck.

Thanks again everyone,

-Flecko

[Flecko]

Also, given the correct voltages, etc, should the 6581 SID get warm at all to the touch? Mine gets a touch warm...and I don't think thats good.

I'm gonna ask this before I plunk a new one down in my circuit. Everything should be working right...this is really bothering me.

Any help at ALL is greatly appreciated,

Thanks,

-Flecko

[LO]

"Warm" ?

yes some people have reported their SID getting real hot... to the point of needing a heatsink! (esp the 6581's)

so dont despair yet

Triple check those traces

are you getting 1mhz via core PIC?

tried playing a note via jsynth?

peace

LO

[Flecko]

Actually yes, its getting its own 1mhz signal. I have a seperate 1mhz oscillator for it, and its been checked and rechecked.

I'm not using a PIC in my project at all though. I'm using an HC11, and i have the SID memory mapped in there. I'm waiting ample time for both the data and address to latch up, so thats not it.

Is it possible to get a oscope-able output on the SID by hooking it directly up to the scope without any sort of transistor or capacitor in there? I'm getting nothing either way.

I ordered another commodore to chop up today, so maybe I can test the chips versus eachother...but I've been over my connections, I'm just not seeing whats going on.

Any other suggestions anyone?

-Flecko

EDIT: additionally, what exact values are people using for caps on the 1st four pins of the SID? I've read a bunch of different values on various sites and even in the 6581 data sheet. Just curious.

[TK.]

Hi Flecko,

regarding the caps: see the descriptions at the MBHP_SID page - these are the perfect values so far.

To get any sound out of the SID, try following settings:

write 0x0f to 0x18 (Volume)

write 0xfb to 0x06 (Sustain/Release voice 1)

write 0x40 to 0x01 (high byte of frequency)

write 0x21 to 0x04 (Waveform control register - saw wave, gate on)

Best Regards, Thorsten.

[Flecko]

Thanks thorsten. I'm re-evaluating my whole setup, something isn't going right...I need to look at the write timing cycles on the HC11 and the SID.

As it is, I have CS and R/W lines on the SID wired to ground, which I don't think works when taking a closer look at the timing diagram. In my mind it should because I always want to be writing to the SID and never need to read it. Mindrealm informed me that he has the SID and the HC11 sharing a 1mhz e clock, which confuses me a bit, but if he got it working, then surely I can figure it out.

Thanks again for all the help,

-Flecko

[TK.]

Yes, thats the error - you've connected two clock domains together and this requires a proper asynchronous bus interface, at least the chip select line should never be activated when the data is not stable.

Best Regards, Thorsten.

[Flecko]

I'm on it, thanks again Thorsten.

-Flecko

[Guest cem3340]

Hmmm...dead SID. Is it laying on its back with its legs in the air? When you poke at it did it move?

Sorry, couldn't help myself. ;D

[Flecko]

Well, I'm sure my SID is dead now. I've got everything absolutely working correctly(both HC11 and SID are on the same 1mhz clock) and still nothing. I wrote a program to play a little tune on it, I tried writing the values by hand via the buffalo monitor, and nothing.

Also, the chip gets real real hot. I mean, almost too hot to touch. Before I go plunking my other SID down in there, is there anything I should look at? I've got it wired exactly like the MIDIbox SID, except I'm using a 2N3903 NPN transistor on the output instead of a BC547.

Should I disconnect the transistor altogether from the output when I test my next chip? I'm only gonna hook it up to an oscilliscope to check and see if the output has anything on it. I mean, to me it seems possible that I've messed up the connections so its somehow drawing too much current.

Anyone have any other thoughts or suggestions? I already broke one R4AR SID, lets not let me break another.

Thanks all,

-Flecko

[TK.]

Some SIDs are getting very hot due to leackage issues, this differs with every chip revision and therefore isn't really an indicator if your SID is still ok or not. Do you hear strange noise when the reset is active (=0V)? This would be a simple way to check if "anything" is working. You could try it also without the transistor (but don't forget the 1K pull-down behind the Audio Out) --- with care! I would also add a 100 Ohm resistor in series to ensure that an unintentional short doesn't damage the output stage.

Best Regards, Thorsten.

[Flecko]

Holding down reset produces a high frequency noise...and then as I release it I get a few audible blips(assumingly everything causing bumps on the power/ground lines as they power up.) So does this mean that its still alive? This is with the output run through a 100ohm resistor, and a 1k pull down, not the transistor.

I have a c64 on its way in the mail, and was planning to test swap the chip in it to see if this one is still working. Perhaps if its still alive, I'm doing something else stupid, but at this piont, I feel i've eliminated enough of the variables to remove the guess work.

I have to thank you personally Thorsten, you've been very helpful in all this, and when I finish my synth, I will be sure to post some pics. I'm either going to retrofit it in a c64 chasis, or build a handmade exterior, haven't decided yet.

Thankyou again,

-Flecko

[TK.]

Yes, so there is a high possibility that your SID is still working.

Did you fix the WR# (or CS#) clue logic in the meantime so that register transfers are working like specified?

I have to thank you personally Thorsten, you've been very helpful in all this, and when I finish my synth, I will be sure to post some pics. I'm either going to retrofit it in a c64 chasis, or build a handmade exterior, haven't decided yet.

fine! :)

Best Regards, Thorsten.

[Flecko]

Yeah, its fixed. I un-hardwired CS from low to being address matched. And since the SID and the HC11 are now on the same 1mhz clock(no external oscillator) everything is matched up nice. I still have R/W hardwired low, but that shouldn't matter now. I had it hooked up to the oscilloscope earlier today, and it apeared that the address/data/CS signals are all lined up nice.

Thats why I'm really stumped this time, because I really believe the information is getting there in the right order, and at the right time. I'm stumped now, downright stumped.

Maybe I'll just wait until my commodore64 gets here. Until then I can work on my rotary encodre/LCD menu or whatnot.

If you have any more ideas though, I'm all ears. Thanks again,

-Flecko

[Flecko]

Ok, I got my 2nd SID chip in the mail...and apparently the C64 it was in is DOA. So I can't test my old SID in the c64, but I tested the new SID in my hc11, and it doesn't work either.

But it doesn't get hot either. I'm gonna have to go down to the lab tomorrow and figure out what the hell I'm doing wrong. I'm really starting to get frustrated  :-[

Any pointers anyone?

-Flecko

[Flecko]

Ok, I'm about ready to throw in the towel. I hooked my SID up to a logic analyzer today, and the correct data is getting to the correct spots at the correct times, with the CS and RW signals going low at the right time. I've checked and rechecked the voltages at all the pins on the SID and can see they're where they should be.

The output floats around 2V on my R4AR SID, and around 5V on my R3 SID. No matter what commands I send to the R4AR, the output stays the same. On my R3 chip, sending a volume 0x0F causes the output voltage to drop from 5V to around 2V(DC, no oscillations whatsoever). Thats the ONLY command I send that actually does ANYTHING on the output.

The louder I set the volume(going from 0x00 to 0x0F) on my R3 SID causes the output voltage of the SID to go a smidge further down from 5V. This is promising to me in the fact that maybe the R3 SID is still alive. On my R4AR SID, changing the volume does nothing to the output, which is pretty disappointing.

It should also be noted that my R4AR circuit eats up about 400ma of current while the R3 circuit eats up a measly 200ma(this is including all my HC11 circuitry). The R3 chip doesn't get hot at all either....which leads me to believe the R4AR is broke.

I am to the point that I'm willing to mail someone a SID so they can test it and tell me I'm not crazy. I wish I hadn't recieved a broken c64 or else I would test it myself. This is driving me absolutely insane. If anyone can lend me help in any way, please either drop me a message or email me: blf141@psu.edu

I'm in dire straights here, I probably wont' be able to sleep now  >:(

Thanks again everyone, I appreciate all the help.

-Flecko

EDIT: Also, I am very very greatful to everyone here for listening to and answering my questions. This isn't even really the right place to ask since I'm not building a MIDIbox, but I can't find anywhere else on the net with experts on SID chips. So I thankyou all for tolerating me. I really appreciate all of this.

[TK.]

Hi Flecko,

it doesn't really matter if you are asking on a MIDIbox related topic or not, most of us are interested in any DIY project and in exchanging experiences.

Based on your descriptions I guess that the R4 SID is really dead, but the R3 behaves correctly. The DC offset changes with the volume - this "feature" makes it possible to playback audio samples with 4-bit resolution.

Did you also try the other voices? Maybe it's just a configuration problem... it especially makes sense to write defined values into every register (just write a zero into unused registers) for a proper setup

For testing the SID: maybe you should give us your location so that somebody from the same country could help you (-> minimal shipping costs)

Best Regards, Thorsten.

[Flecko]

Thanks again Thorsten. A friend of mine has a working c64 which I'm gonna get over the weekend, so I can at least test my SIDs to see whats up. I think I can say the my circuit is correct, and that maybe the SIDs are at fault, but I'll be able to test it on my own now and figure it out.

I've been in touch with MindRealm(he's built a SID synthesizer based on the HC11 too) and I'm pretty sure I've done this correctly. We've been talking about it back and forth and I think its down to the SID chips, I have other homework due soon, so I can't work on my SID stuff till this weekend, but I'm excited now.

Thanks again for all the help, and hopefully my next post will tell you about how good it works now  ;D

-Flecko