logo64 Posted July 3, 2005 Report Posted July 3, 2005 Hello,I am trying to get my MBox sid up and running - have both the Core and SID boards stuffed, and built the power supply as in mbhp_sid_c64_psu.pdf. It seems like everything is connected properly, but when I turn it on, the 5V output from IC3 hits 5V, sits there for 3 sec., and then drops to about 1.5V. It doesn't get hot (I don't leave it on for more than 5 seconds though). Any idea what could cause this? The 12V IC4 on the SID-R2 board keeps its voltage fixed at 12V. I checked the Cap and diode polarities on the CORE board, and they're all fine. Bad voltage regulator?A little more info - the input voltage to IC3 is also dropping. From 12 V to a couple volts. Not surprisingly, IC3 regulates ok until the input drops below 5V. Hmmm... the plot thickens.Another quick question - Should the second pin of J1 on the SID board (Vs) be connected to ground? Seems weird just leaving it floating...-gerald Quote
TK. Posted July 3, 2005 Report Posted July 3, 2005 Hi Gerald,it sounds like the power routing is not correct, if Vs and Vd are not connected, the ICs are powered through the data lines, and this can cause such effects.J1 seems to be ok, so check especially J2 (the 5V domain)No, the Vs pin of J1 should be left open if the wiring is based on the mbhp_4xsid_c64_psu_optimized.pdf diagram, otherwise you would get a ground loop which would increase the background noiseBest Regards, Thorsten. Quote
logo64 Posted July 3, 2005 Author Report Posted July 3, 2005 Thanks for the response. I yanked the stack of boards, and checked the solder joints, and... sure enough, I had (embarrassed here) missed soldering one of the J1 pins!Easy fix. - Now my SID is making noise. It isn't really in tune, but it's making noise. Now, on to getting my LCD and CS working. I transfered "setup_6581_with_cs.syx", but that wasn't enough to get the LCD working... will have to dig through the FAQ.What are the two trimpots on the Core board for? Tuning? LCD contrast?One more question. The SID chip I'm using is flawed - one of the three voices doesn't work. I discovered this using Triad's MIDISLAVE. Does Midibox SID use all three voices?-gerald Quote
grnsky Posted February 22, 2009 Report Posted February 22, 2009 One thing I know - the trimpots are for brightness and contrast for the LCD Quote
Goblinz Posted February 23, 2009 Report Posted February 23, 2009 Wow, mega bump. That thread is nearly 4 years old! The OP hasn't even logged in for over 2 years! Quote
stryd_one Posted February 23, 2009 Report Posted February 23, 2009 Heheh, I almost removed it until I realised it was an otherwise-unanswered question.... but wow, what a bump ;) Quote
nILS Posted February 23, 2009 Report Posted February 23, 2009 Okay, then, while we're at it ;)One more question. The SID chip I'm using is flawed - one of the three voices doesn't work. I discovered this using Triad's MIDISLAVE. Does Midibox SID use all three voices?Yes, it does. Quote
Futureman Posted February 23, 2009 Report Posted February 23, 2009 Well, should someone PM them to announce we have an answer for their questions? Quote
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