sparx

Well trying to desolder the SMT chips to see which one was faulty was a no go, so I now require the above, OPL3 PCB, sound chip and the 2 DAC's. It was good so if I can get two lots that would be great, but would be happy with one. Please post with details. Thanks S

Yes replacing the DAC first makes sense, but guess what I don't have any spares of? I'll post in the Fleamarket section too, but if anyone has any spare sets of chips, (think I'll do another one of these anyway) please let me know. I do have a spare YMF262 so maybe that will get replaced first, guess its a 50/50 chance. Thanks again S

Thanks for that nILS, have seen various permutations of the "2 9V batteries as a bipolar supply" but never done it. I can confirm that this configuration will certainly power the Op-Amps in the OPL board should anyone else need to do it. But alas, it looks like it is the SMD chips on the OPL which are at fault as I suspected. Apart from replacing them, any way of testing them to see if its the sound chip, the DACs or both? S

Thanks, all voltages are fine, CS works fine, uploads work fine, already tried to operate OPL and core with no CS, still grungy. Which is why I think its possibly either the PSU or the OPL board. Other thing I was thinking about doing, is running the OPL off a couple of batteries, has anyone tried this? If so can they post details? Thanks S

Its a newly completed build, certainly the board was working fine before the CS was finished, but now sounds distorted. The original PSU was replaced as it was recycled and there was a smell of burning electronics and bits got warm which may have been normal, but with the new one the results are the same. Voltages are all fine. Op-Amps are new as well. As it stands, I can't rule out the OPL board or the PSU which is why I want to test the OPL board in a known working system. Will throw the net a bit further, can anyone, anywhere assist me? Thanks S

Yes, it looks like you got it! There is no ground for these LED's, its provided by J4 and the output of those 4 pins goes to the DIn board via the diodes.

My FM is sounding distorted and grungy. I've checked the usual things and it all seems fine so what I can't rule out is that the surface mount chips aren't faulty. Is there a fellow midiboxer, ideally in London UK area, who would be willing to try my board in their set up? Its a long shot, but it really would be appreciated. Thanks S

Yes check the soldering first. You could try re-uploading the application or trying the core in another set up.

9V 1 Amp should be adequate at least to get you going. 3 LCD's might be a bit much for it but 1 should be fine. Good luck.

Check all slder joints, recheck the wiring, load the testone app, it makes troublshooting a lot easier. Guess I asked for that... :yes:

Yes, I can see that, thanks, the question was why two stereo pairs instead of one? S

That is how I understood it to be as well. I'm trying to finish mine and just wonder why the audio is routed to two stereo outputs instead of just the one? No real problem, just wondering. Regards S

Or for simple note on/off use an EPROM. Each button from the Sax tied to the EPROM inputs. EPROM outputs to Digital In board. When, for example, buttons 1 and 2 are pressed, the contents of this address will be at the output which you could use to drive the DIn board. Downside is no velocity. S

How many keys does this Sax have and how many notes are possible? Regards S

Have you looked at Maplin? www.maplin.co.uk Stock code: YU32K Looks nearly the same. Where are you that it costs so much to ship? I would be happy to get one for you and send it at cost. Regards Sparx

Harry Use the HC165, do not use the LS version The 4051's might be OK, but why not use the specified part? They're quite cheap and you can get kits from Mike or Smash. Digital ciruits generally run at +5V. The core board has a +5V regulator (7805) which is used to supply the other circuit boards when connected. S

Harry, are you making your own boards? You may want to look at the PCB's from Mike or Smash TV, it might save you lots of time in the long run. S

Hi Harry Yes you need a few buttons for the LCD, I used a 16 x 2 LCD and have I think 4 buttons. For the convenience and niceness of having the LCD it's a very small sacrifice. Post back if you need more help. S

I'd include the LCD, as Phil says, it really will show you what is going on. Not only that, when you turm your pots a nice little bargraph is displayed which will impress everyone. Don't forget that you will need to ground any unused pins on the AIn board as this will cause the PIC to output streams of data wehich you don't want. S

I'd try a different supply. In particular one that supplies +/-12V, I was using a +/-5 and had something similair, switching to a different supply fixed it right away. It was as though the op-amps needed more "oomph" (technical term) to work properly.

Yes that is correct, the three diodes in series pointing down is the correct way to do it. (Am not saying the others are wrong, just this way is more usual). I wouldn't bother with the cap, but if I did, the value seems fine. Good luck and post back if it still persists. A little question though, why don't you use a dual supply circuit (+/- 12V) and tap +5V off this such as is used in the MBFM? S

The usual way of increasing the output of a voltage regulator by a couple of volts is to put diodes (e.g. 1N4001) between the Ground pin and the Ground connection. A couple of diodes will increase it by 1.4V (ish). Am not saying that what you have done is incorrect, but its more common to use diodes. If you need an unusual voltage or any more than a couple of diodes worth, use a variable regulator such as LM317. As I'm old and wise, (apparently!), I would suggest you revise your power supply. Please post back if you need any more help. S

Yes the power supply looks like where it might be coming from. The bottom 7805, you may want to use diodes instead of resistors to jack up the voltage, or even a different regulator - 7809? I would definately try using seperate power supplies at least until you can isolate exactly where the problem is. S

Yes, it is certainly possible and fairly easy to do provided the mains transformer can offer the power you are after. But I wouldn't reccomend it for a number of reasons. One being that if this power supply develops a fault somewhere, you will be without your MB6582 until its fixed. Given that most MB6582's already succesfully built use a C64 power supply and they are readily available, it would seem the most obvious choice, if only to try. If you do decide to build your own supply, please take care with mains voltages. S