I tell you what, it is actually quite rewarding doing this troubleshooting!
When you find the fault, or at least define the problem, there is that sense of achievement…
I had 6582As and 8580s only in the 1st two modules. When I tried 6581s in the non-working modules they worked. So problem is either all my 9V SIDs are blown, or my 9V line isn’t working.
Let’s see which…
So I’m thinking this is a peculiarity of the application that it doesn’t care about the RHS SID CS pin.
Quite possible… it was written before MB-SID V2 and stereo SID support.
However, I am very sure the testtone app outputs on both channels.
I had 6582As and 8580s only in the 1st two modules. When I tried 6581s in the non-working modules they worked. So problem is either all my 9V SIDs are blown, or my 9V line isn’t working.
Very unlikely you blew the 9V SIDs unless you had them connected to 12V, and you would not have inserted a SID without checking the voltage on pin 28, right?? 
Of course! 
My 7809 regulator was “missing a leg.” I lost a trace when I had to rework it to fit in the heatsink and neglected to test.
Man this feels great. All tests now passed.
Funny, now that I’m finished I have this serious desire to make another midibox!
No I think I’ll make some music first. 8)
Funny, now that I’m finished I have this serious desire to make another midibox!
That’s called the “Imbambcia”*-syndrom.
*I must build another MIDIbox cause I’m addicted.
I finally uploaded applications to the mb-6582 with another MIDI interface.
Thanks to everybody
I finally uploaded applications to the mb-6582 with another MIDI interface.
Thanks to everybody
Thanks for the beer
Hi Guys,
I’m nearly finished my mb6482(after a year of gathering bits).
Seems like I have the problem as noted in post one and now that I have found this thread I’m hanging to get home and test some more.
I do have one question.
What should the resistance between 5v and ground be?
I’m measuring abour 500ohms
The reason, before I insert the SIDS I measure 5v and all the voltage test points are fine.
The LCD lights up and says ready.
Once I insert the SIDS, the 5v line drops to 1v and the LCD lights no more.
I’m using option A for the PSU.
Your assistance is greatly appreciated.
Possibly your C64 PSU is unable to supply enough current to all the SIDs plus the LCD.
I wouldn’t call this a common problem, but I know of it happening with a few people.
Essentially each SID will draw 100mA on the 5V supply.
How many SIDs did you insert before you observe the 5V drop?
Possibly your C64 PSU is unable to supply enough current to all the SIDs plus the LCD.
I wouldn’t call this a common problem, but I know of it happening with a few people.
Essentially each SID will draw 100mA on the 5V supply.
How many SIDs did you insert before you observe the 5V drop?
Hi Wilba,
Looks like you were spot on!
I did some testing after reading your suggestion.
Luckily I have two c64 psu’s on hand.
The one I was using stopped lighting up the LCD after 6 chips.
The other is fine for all eight.
However I have noticed another problem.
With one of the chips(it might’ve been a dodgy connection) all the LEDS lit up but the LCD was blank, this happened twice(different insert/pulls) on the one chip.
But when I replaced the PSU and used all chips it didn’t happen again.
Ok, so I’m on the right track, now I gotta work out the matrix.
Thanks Wilba for the design and support!
Once I get rocking my midibox and can pack up my solder station (to make the lady of the house happier) I’ll donate to your beer fund.
P.S.
Just did another A/B psu test and the first one isn’t up to snuff.
Hi Wilba,
Looks like you were spot on!
I did some testing after reading your suggestion.
Luckily I have two c64 psu’s on hand.
The one I was using stopped lighting up the LCD after 6 chips.
The other is fine for all eight.
However I have noticed another problem.
With one of the chips(it might’ve been a dodgy connection) all the LEDS lit up but the LCD was blank, this happened twice(different insert/pulls) on the one chip.
But when I replaced the PSU and used all chips it didn’t happen again.
Ok, so I’m on the right track, now I gotta work out the matrix.
Thanks Wilba for the design and support!
Once I get rocking my midibox and can pack up my solder station (to make the lady of the house happier) I’ll donate to your beer fund.
P.S.
Just did another A/B psu test and the first one isn’t up to snuff.
Got it all working. 
Is a little buggy, got some strange noises when I move knobs and one of the voices doesn’t release.
Will trawl the forum for help. They’ve been beneficial so far.
Cheers
A