MBSID CS step B - many problems - pls help!

[Hermes]

Hello everyone

Some time ago I had built an MBSID without  CS (I core and 1 SId module with 6581 chip), which worked without problems - I had also connected an LCD on it.

Recently I built another core + SID  with a 8580 chip, so I decided to upgrade to CS step B nad also use TK's modified C64 PSU.

Initially, although I was sure about my connections things did not go as planned - I managed to get the CS working but I had no sound coming out of the my SID. At one point the fuse of the C64 PSU was burnt and I had to replace it - the 100 pF cap of the C64 PSU circuit was also burnt so I replaced it too.

After these replacements my 6581 SId worked !!! I was even able to load the preset patches on a Bankstick and scroll through them and hear all of them. But the 8580 sid nver worked. After examination I noticed that the R11 resistor of the 8580 core was un soldered, so I soldered it back. And after that nothing woked any more ... - even my lcd does not have stalble lighting and brings out random characters :( :'(

I must add that I do not use the 1.0 Mhz oscillator - I have connected my sids directly to the cores (PIN #17) for clocking.

The voltages are Cores: 5.37, SIDS: 11.98 (6581), 8.87 (8580), 5.37 (serial register chips 74hc595)

Please help!!

[TK.]

Hi Hermes,

check the tracks around the MIDI In port, it seems that you damaged one of them with the soldering iron (by fault)

Best Regards, Thorsten.

[Hermes]

Hi Thorsten

Thanks for answering, as always. There doesn't seem to be any problem with the tracks around the midi in port.

But I checked for short circuits with my multimeter and I noticed something fairly strange: With the mutimeter on beeper, when I check for short  between #11 and #12 pins of the PIC there is a "beep" generated from my multimeter, which lasts for only about 1 sec and then pauses. If i remove one of the multimeter checking needles and then put it back to the pin again, nothing is heard. Now, if I change the position of the needles and put the red needle to the pin where the black needle was and vice versa, I hear the 1 sec. "beep"  again, which then pauses. The same thing happens when I check for short between the Vs  and Vd line of the 5V output of the C64 modified PSU circuit  (I mean the output after the 100nF cap) and it also happens when I check between any of the Vs, Vd and Vo lines of the LCD output port of the core.

Is all this behaviour normal or not? (I guess not) ??? 

I must mention that I did all the tests after disconnecting the second core completely from the power and from the first core

In addition the midi input monitor of midi ox, I get random events from the core midi out, like several repeated lines of pitch bend messages or several repeated lines of Progr change Acc. Grand Piano etc.

I can not fix this problem although everything seems to be ok in the core soldering ...

At some point I even thought that my multimeter was damaged or that a cap or a resistor or a diode in the core was burnt

Is there any possible way to get out of this or shall I have to build another core?   :P

Also are the voltages I get correct ?  Cores: 5.37, SIDS: 11.98 (6581), 8.87 (8580), 5.37 (serial register chips 74hc595)

Thank you in advance for you time and for your help

Best regards

Dimitris (Hermes)

[TK.]

Is all this behaviour normal or not?

yes, it is - this effect is caused by the caps. However, it means that there is no short between Vss and Vdd, thats the only good input.

In addition the midi input monitor of midi ox, I get random events from the core midi out, like several repeated lines of pitch bend messages or several repeated lines of Progr change Acc. Grand Piano etc

Does this also happen when MIOS is uploaded again?

-> Remember that MIOS has to be uploaded within 2 seconds after power-on

-> use MIOS Studio which provides a proper error handling (-> http://mios_studio.midibox.org)

Best Regards, Thorsten.