why my sid doesnt play any more?  

Testing/Troubleshooting
1

Im trying to resuscitate my sid synth, which time ago worked, but that after the mios update and the change from 6581 to 8581 it doesn emit any sound.

the mios seems to work: the ping works, the sid application is loaded, and if i request a sid patch by sysex i receive the right message.

the problem is that, when i turn on the unit, i only listen to two electrical transient - one at the power up and one after (in midox), i see that some program change message is coming.

i have checked the sid voltages, and they seem OK, both on the sid and on the other two IC.

i remember i changed the caps for the sid filter, now i read 682Z on them, but sincerely i cannot remember their precise values, and i’m perhaps not able to interpret correcly their value… are they correct?

what kind of checks should i do???

i even tried to use jsynth to edit some patch, but with no results, and to substitute the 8580 with  another one…

thank you very much!!

2

Hi Matteo,

I’m not sure about the caps, but you should hear some sound regardless of the value. There is a program in the MIOS download section which helps you to debug the SID module. Search for “mbsid_interconnection_test.zip” and follow the instructions in the main.asm header:

; A CORE->SID Module Interconnection Test
;
; This application allows you to check the interconnections to the SID module
; with a multimeter. You can control the SID pins by sending a Modulation Wheel
; event to your MIDIbox SID - just connect a keyboard or use
; MIDI-Ox (View->Control Panel)
;
; By default all unselected pins are 0V, except for the CS# pin which is 5V
;
; The Pins are mapped to following Modulation Wheel Values:
;
;    # 0: Pin A0 = 5V
;    # 1: Pin A1 = 5V
;    # 2: Pin A2 = 5V
;    # 3: Pin A3 = 5V
;    # 4: Pin A4 = 5V
;    # 5: Pin RES# = 5V
;    # 6: Pin D0 = 5V
;    # 7: Pin D1 = 5V
;    # 8: Pin D2 = 5V
;    # 9: Pin D3 = 5V
;    #10: Pin D4 = 5V
;    #11: Pin D5 = 5V
;    #12: Pin D6 = 5V
;    #13: Pin D7 = 5V
;    #14: Pin CS# = 0V
;
; The pin names are also visible on LCD (if connected)

Results?

Best Regards, Thorsten.

3

i remember i changed the caps for the sid filter, now i read 682Z on them, but sincerely i cannot remember their precise values, and i’m perhaps not able to interpret correcly their value… are they correct?

682 is a 6.8nF cap, the Z is a tolerance code, meaning +80%, -20%.  Most common ceramic capacitors are “J” tolerance (+/- 5%).

For more info on the cryptic capacitor codes see http://xtronics.com/kits/ccode.htm

Have fun!

SmashTV

4

THE RESULTS:

the test with the MIOS interconnection test script worked, altought there is something strange, which i don’t know if it’s OK or not:

when CC1 shifts from 15 to 14 the pin A0 read 5 volts (and remains at 5), but when i switch from 13 to 14 nothing happenes

similar, when CC1 shifts from 13 to 14, pin D7 reads 5V

the other readings are OK, and no pin shows 5V when the corresponding CC is not selected.

then, i measured all the voltages on the SID during “normal” operation, with SID 1.5c:

Cap1a      5

cap1b      5

cap2a      5

cap2b      5

res#      5

clk      2

rw#      0

cs#      5

a0      0

a1      0

a2      0

a3      5

a4      5

vss      ground

d0      5

d1      5

d2      5

d3      5

d4      5

d5      0      

d6      0

d7      0

poty      0

potx      0

vcc      5

in      3 (about)

out      4 (about)

vdd      5

5

Hi Matteo,

seems to be ok…

Next question: which MIOS version are you using?

My recommentation: MIOS V1.6 and SID V1.6alpha3

A sidenote to give you an impression about the possibile hardware errors: some weeks ago a user had similar problems with his MIDIbox SID modules. After a lot of forum postings he finally sent me the modules since he wasn’t able to identify the root cause by himself. After some quick checks I found out that it wasn’t only one problem, therefore it was nearly impossible to support him via forum under these circumstances. Here a list:

  • bad soldering joint at the bottom of the core module (J10:MD pin)
  • slack joint (loose connection) between the SID and the core module - sometimes it worked, mostly not…
  • a tiny solder blob caused a short circuit near of IC3 of the SID module
  • one of the SID was defective

So, what should I say…

  • ensure that the modules are properly connected - use ribbon cable, they are easier to solder.
  • carefully check the bottom of the PCBs for short circuits
  • try different SIDs if available
  • connect a LCD if available, it saves a lot of time during debugging
  • always use the latest MBSID and MIOS release (remember that MIOS has to be uploaded with the first level bootstrap loader…) to avoid compatibility problems
  • try alternative applications (e.g. the sidplayer)

Best Regards, Thorsten.

6

thanks for the help, althought i think i double / triple checked everything…

i particular, i checked all the connections between core and sid by checking the connectrion directly from the PIC pins to the SID/ICs pins.

the worst thing is that when i mounted, in the past, the 6581, all was good. but when i switched to 8580 things went bad: first i had problems with the note playd, then after some time no more note was produced.

i have 2 8580, and none of them works.

since the core modules responds to the SYSEX correcly, can i assume it is fully working?

a little test i did: if i remove the clock input (which comes from the core module) and i turn on the SID, i only hear the electrical transient of the power on. if i connect the clock, i hear two transient, the first of the power up and the second, that should be the “initialisation note” produced by the SID.

how can i check if the SID is working?

where can i find sidplay? the page

http://www.d.kth.se/~d93-alo/c64/spw/sidplayw.html

doesn seem to works

i think that i will try to return to the 6581… or perhaps, if you agree, i will send you my modules…

a little addendum: can the capacitor type on the SID filter affect

the output? i don’t know which kind of caps i mounted (they are NOT electrolytic caps, anyway! :slight_smile: ) but i know there are a lot of caps shapes…

7

continued via PM

8

@ the filter cap question. there is a difference, there are at lest two threads here somewhere discussing it, one of wich was initiated by me(which could help you narrow down the search) I would search for sid and capacitor or something like that.

9

results:

i changed the caps with no improvement.

tried the “siplayer” but the unit only ouputs “electrical transients”.

the solution: i switched back to sid 6581 and everything now is ok… the two 8580 are going to an holiday on thorsten house to see if they are working or not!!!