wicked1

I've got the rack mount of that synth, and that's one of them that needs work.. It has a few bad encoders.

Urg.. I'll be doing a lot of repairing for quite a while, I think.. Many old projects and even commercial gear that's all showing its age. Somehow sitting in storage was worse for it all than being thrown in my truck and driven to venues every weekend. I've got a huge modular I built between 10-20 years ago, and it's full of glitches. That's going to be a nightmare to fix. All caps age, but there was a problem w/ the electrolyte they were using 15-20 years ago and those things failed in everything.. From commercial products like computers and tv's, to DIY stuff like my modular.. At least electrolytic caps are big and easy to find and replace. I'm getting too old to work w/ SMD stuff :(. Vision and steady hands are a thing of the past. Ageing is a b*tch, for me and caps.... I used cheap sockets for all the IC's in all my old projects, too, and those have gotten oxide layers or something and need to be cleaned or replaced, too :(

I figured out the 2nd issue too.. My 12v line was about .5v low. I added some capacitance after the rectifier and it increased the voltage a little. Now the 6581 performs as it should.

I just got my mb6582 out, after about 6 years of disuse. It had a few issues I tracked down to broken wires and bad connections in IC sockets. All that's fixed. I'm having a few issues w/ my filters. Edit- solved my first issue.. Filter wasn't giving me the full frequency range. Apparently I had to calibrate it in the ENS menu, for an external filter that is not currently attached. 2nd question, I have mostly 6582's, but have a pair of 6581 SID's on one core, and when I enable the filter on them, there is a loud hiss. If I disable the filter, it's got the usual background noise all the SID's have. But the as soon as I click the button to enable the filter for the oscillators, the hiss gets loud. (Ext in is not enabled). Is this normal for 6581's? Thanks for any advice!

That's kind of what this is turning in to! I'm actually thinking of having a rack panel made for my 6582.. It would still take the same formfactor, so I could use the same control surface PCB.. just have dead space to one side to make it rack-mountable. (Mount the filter components back there, or something). Oh, maybe I can fit the FM in that space.... hmm. Off to the drawing board. (which is actually just a different screen here at my same desk :) ) In the end, the goal is to have the core of my studio transportable... Couple of filter and FX boxes. MB Seq, SID and FM. 9090, novation synth, and the two problem bits... mpc2000xl and mixing board (those are "problems" because of their size and are obviously designed for desktop use)

Only because the draw is so uneven... Almost everything is pulling from the +12 side, which is why I have no headroom. The negative 12v side has several volts headroom. It's only powering my filters. My thought was basically the SID's themselves are probably drawing most of the power. I've got 4x9v sids, and 4x12v sids. I was thinking I could split the load so the 2ndaries of my transformer are doing equal work. But.... like you said, it probably won't work, and it is working successfully now...... so, I suppose I'll forget about it :).

Thank you! I'll have to change the pinout, as I'm supplying all the clean DC voltages to the 6582, but that's under control.

New question... In the end, my power supply is like the wiki, one rectifier, Center tap configuration. Could I use the +9v regulator on the negative rail? So like, connect + to 0, and - to -12? I know that will give me 9v, but its ground would be 12v lower than neutral, right? Then I guess it depends on how Wilba set up the 6582... does everything share the same ground? is my thought process correct on this? If so, do you know if it will work w/ the way wilba has the 6582 set up? It's really a shame there are no schematics for his designs!

Well, amazingly, the LDO regulators and the Schottky diodes (salvaged from a PC power supply) seem to be working. I've only got about 300mv to 1/2v headroom under load, but I can't hear any buzzing. And, that's worst case scenario.. For some reason, the outlets on the other side of my basement are about 8vac higher in voltage, so I've got no problems there.

I'm looking for a c64 style power plug. I built my own power supply for the 6582, but want to use its c64 power jack. I'd rather not cut the end off my old c64 power supply, so does anyone know where I can get a c64 style power plug? Thanks

Nice! was converting the layout easy? I want to make one for the 9090 too.. Been waiting tooooo long for my panels, and these are much less expensive.

That working c64 and burger time loaded bring back some memories! A long time ago, my sister moved out and took the commodore w/ her. She recently asked if I wanted it back. I said yes, and she brought in the monitor and disk drive and said, we threw the keyboard away... Figured you didn't need that. URG!

Or, just make them analog for real time control (in addition to the CV from the FM), and accept I can't record their values......... (for live stuff and having fun). The dedicated filter box seems better and better all the time... I have an electrix filter factory, which is a midi, time synchronized filter and lfo. It's very useful. Can use it on drums, turntables, whatever synth, etc. Building one w/ the cv2 could be very interesting. Not only midi/time synch LFO, but EG's as well. Could make a control surface w/ the LFO and envelope controls. Assign other CV's to the pitch and res, and I think all of that is saveable in a patch.. I'll have to read up on the cv2 again. But my idea for that is I think (correct me if I'm wrong) I could put it on the same channel as the FM, and when a key is pressed, it would trigger the envelope on the filter box, too... So then the FM's built in EG5 and LFO's are redundant.

I get all that. I've got the aout ng built, I've got filters. I've got them working together. (both w/ the SID and the FM. I do have one issue there... SID needs 2 aouts for the four filters, fm needs one.. But that's for another topic) But, there are obviously no filter control knobs on the FM. So, say I want patch 1 to have the filter frequency at 50%, and patch two to not use the filter at all (so, frequency at 100%). Where do I set that? And, the resonance as well... I get that I can assign LFO's and EG's to them, and set the level those will affect the filter... But just to leave the filter on steady at 50% vs 100% frequency? Or, doing a filter sweep while I fade in a part.... My guess is I'd have to go in to the menu and use the offset value, right? But, I like to tweak filters a lot, so I'd rather have knobs for it. (which by the end of the day yesterday, I started thinking about building a dedicated filter box w/ the cv2 or something, to give me full recordable filter control for the FM... But, thats not realistic, as I'd like to save my money and share the filters between the FM and sid.)

I want to put a filter on my FM, and have been brainstorming about how to build a filter box that the SID and FM can share.. BUT, I've just realized I need to figure out something even more basic, first. There's no way to set the initial frequency and resonance. Unlike the SID, I'd have to put knobs on the filter box for the FM, right?

No, I mean sticking w/ the 12v transformer. So, then my 9v regulator is still happy (that's the one I was concerned about w/ the 15v tformer). I'll switch the 12v regulators to the low dropout, so that maybe they'll work w/ the 12vac transformer. 5v regulator is switching, so I'm good there either way.

Personally, I think I'll try the schottke diodes and LDO regulators. If they work and it's burning less energy, that's all good!

Thanks everyone. What's odd is I just finished the 9090 and used a 2x15v tx for it, and don't seem to have any problems w/ it regulating 15vdc. But, it's a different transformer, so irrelevant, I guess. My only concern w/ a 15v tx for the 6582 is, I'm also using a 9v regulator, and that's a pretty big drop for it. Is there a down-side to using LM2940's instead of the LM79* regulators? I'm thinking there must be a reason the LM7* series is still the standard.

Well, it was a ground loop.. sorry, I'm an idiot. Rewiring it w/ dual secondaries, two rectifiers basically made me clean up the grounding scheme. I rewired it last night as center tap w/ careful attention to grounding order, and it's quiet. The unbalanced load definitely makes the volts coming out of the two halves of the transformer uneven, but the regulators fix that and it shouldn't cause noise. New problem though... My 12v transformer along w/ my sagging home power (it drops about 10v when the air conditioning turns on) doesn't leave enough voltage for my 12v regulators, and they are noisy! When the AC is off, everything is quiet. I guess I need a 15v transformer.

If one of the bosses gives me the OK, I'll upload it. Otherwise, everything people need to do the work themselves is in the wiki. It's basically his board w/ larger traces and pads for easy etching. (Or just PM me, if someone wants it)

Someone has me thinking I could have possibly had a ground loop causing the problem. I'm going to test that theory. If it's definitely the unbalanced load causing the problem, I will update the wiki. Mine is dual secondaries, so that is what I did. Only, I didn't connect the grounds together until after the regulators, where your example has them connected after the rectifiers. (I'm not an EE, and don't know what difference that makes.. works, though)

I etched a PCB for it. Had to bridge a bunch of ground connections on the bottom, but it wasn't difficult. I can send you the artwork, if you're set up to etch PCBs.

Well, not really worth it. My idea works, I've got positive and negative w/ no buzzing now. But, the wiki "center tap" option isn't a good idea for running the 6582 and filters... There's practically no draw on the negative half, and everything is pulling from the positive. Center tap supplies apparently don't like that.