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Paia 2700/4700 power supply and other questions
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Author Paia 2700/4700 power supply and other questions

dvdsmoke

I recently acquired an assortment of very old and questionably functional 2700/4700 modules. however, i am missing the power supply and unable to test them. I have mostly dealt with Eurorack in the past and am not too familiar with these old modules, so i have a few questions....

(1) what's the quickest, cheapest (and best) way to power up these modules? it looks like they take a regulated +9V, -9V, and an unregulated +18v.

i found schematics for the old 4700 power supply but i'm thinking there is probably an easier way to build it with a wall wart. is there some circuit i can slap on the end of a 9V AC wall wart that will parse out all the different voltages necessary?

(2) i'm a bit confused about what kind of jacks/cables these things use. is it 3.5mm and banana? further adding to the confusion, one of the modules has a homemade panel with a different kind of jack i've never seen before. is that mini-banana? see the orange jacks in the pic.

thanks!



Rob_C

PAIA modules use plus 9 and minus 9 and plus 18 volts. The power supply does not have to be regulated, but most find better results using regulated 9 volt supplies. Modules that need regulation such as the oscillators have rudimentary regulation on board.

Yes, you can use wall warts, but you will need two of them. Two wall warts that output 9 volts DC can create a bipolar power supply. Generally this type of supply is used temporarily and may lack suitable filtering for audio use and I would not use this type of supply with any expensive modules. Connect the plus of one wall wart to the minus of the other. This connection becomes ground. The other two connections are your plus and minus. Check everything with a volt meter before hooking anything up.

Or you can buy this inexpensive ($27) linear triple output variable power supply kit: LINK

PAIA used different jacks and cables for audio signals and control voltages in the 2720 and 4700 series modules. Audio signals are patched with 1/8" (3.5mm) cables, and control voltages are patched with what is called "tip" jack cables. Tip jacks are essentially what you find in smaller multimeters, but they are not bannana jacks. It appears that those smaller orange "freq" input jacks in the photo are tip jacks, but lack the round "lip" like the other ones. Tips jacks are still easily found but ones that exactly match these PAIA modules are almost impossible to find.

Some users replace the tip jacks with bananna jacks. Others replace tip jacks with 1/8" jacks to use the same patch cable for audio and control voltages. There are advantages to each of these approaches but I prefer the modules to remain stock. Kind of a period thing from the 70's and 80s.


TheDegenerateElite

Nice find.

The manuals and schematics for these are on the Paia forums.

The 2720 power supply also had some -5 to +5 and 0 to 5 volt bias attenuators/attenuverters on it. They are pretty important for using many of the CV inputs for the modules, like the low Pass Filter which lacks any knobs.

There was an article about building a 2700 synth in Radio Electronics mag in 1970 something that is also available on the Paia site. It contains plans and pcb patterns for the power supply.

The stock power supply did suck, being unregulated, and Paia developed a new one, the 4771, with the knobs and mults of the older 2700 one.


The pin jacks, or tip jacks, can work using the speaker connector pins that are available at Radio Shack or other suppliers.


emmaker

I built a 4700 back in the 70's. It was my first modular, while far from the best it was a lot of fun and I miss it sometimes.

It really wasn't usable with the standard power supply, lots of hum and noise. Before I could really use it I built a new, regulated supply using 3 tab regulators (78XX & 79XX).

Jay S.


valis

Good info posted here already. You really only need one power supply (say 18v) and then you can use +/-9v regulators from that source. It is true that the VCO has regulators on it but I still prefer to use regulators at the source. Plus I'm not sure if that VCO pictured is actually of PAiA design.

You can actually substitute the 18v supply with a 15v supply but I'd still recommend using an 18v supply. I used to have a PAiA blog but don't maintain it anymore. I've actually taken down a lot of the info (sorry, I planned to do better write ups) but this may still be useful

http://obsolete-synthesis.blogspot.com/2012/02/paia-27204700-quick-hel p.html

I talk about substituting the pin jacks for bananas but I've changed my mind on that. I now use all pin jacks. It's just my preference in keeping the machine in its more original form. Your call there. I actually have some puns as audio outs for easy fm and other fun but that's just me. The "wings" have format converters on them.

There is no way in hell I'd power up all of those modules at once though. You definitely want to isolate the modules and test them one at a time. I'd say there's really no way to avoid a re-cap of the polarized capacitors. I've seen some crazy things in my years of collecting old paia modules and your modules look as though they've sat in not-so-ideal conditions for a long time.

So, in short you need to (1) get a new power supply (go regulated all the way). I bought a new transformer for each of my systems and tap all of my power from there. (2) Inspect and recap the modules. (3) Test each module separately, then power them together.

This is a great opportunity to learn about electronics but what you have is not plug and play. You'll need a soldering iron and multimeter for sure (but as I constantly preach, ALL electronic musicians should know how to use a multimeter and knowing how to use a soldering iron is very beneficial as well). Is sounds like you're a bit of a novice so go slow. Most parts are easily attainable but the less damage you do, the easier troubleshooting will be. Never apply power to anything unless you understand what you are doing. The good news is these modules aren't very complex and can survive a good amount of abuse.

Scott at a PAiA is great. Good luck.


dvdsmoke

thanks everybody. all this information helps a lot.

i plan on making a ghetto rig and i'll post photos when it's up and running.


valis

It will be a fun project. Don't hesitate to post if you have more questions thumbs up


dvdsmoke

thanks! valis is my favorite book.


dvdsmoke

i'm looking at a schematic for the 4771 power supply that i found on this page
http://sonic.net/mjones/archive/docs/index.html#pdocs


now this schematic is raising a question:
when people say "regulated 9v" do they mean 5v? because i'm seeing 7805's on the schematic here, which regulate down to 5v. i thought these paia modules used +/- 9v, not +/-5v.


Rob_C

It's definitely NINE volts, not five.

The Design Analysis section of that manual explains it.


dvdsmoke

quick update: i acquired a power supply. replaced caps on the "control oscillator" module (lfo+noise osc.) and the noise oscillator is working!

ok back to work It's peanut butter jelly time!


Rob_C

Good work!

If you don't have a PAIA keyboard or a PAIA power supply with the 0 to 5 volt bias controls, you can use the output of your control oscillator LFO as input to the "freq" jacks on the VCO to test your VCO. [You probably already know that from your experience with Eurorack.]


dvdsmoke

yes, Rob! that's exactly what i've been doing. only I don't have a negative 9v supply presently so I am unable to test the oscillator. ordering some 7660s to ameliorate the situation.

however, i have been able to test a few things that require only +18 (and gnu). it appears as though the bandpass filter module is working like a champ. the lowpass filter works but is really quiet. and i'm not getting any sound out of the sine/pwm module.

i still need to poke around more, but i'm feeling optimistic. Rockin' Banana!

any ideas of where i can get some PLUGS for these weird PIN JACKS. thinking of replacing them with banana....


Rob_C

Tip jacks and plugs can be ordered from Mouser or Digikey, or just check Ebay using "tip jacks" and "tip plugs" for search terms.

The 2720 low pass filter was designed for low cost and is more of a tone control. It will not have the resonance of true low pass filters. Maybe that is why it seems quiet, or something else could be going on.

The sine/pwm module requires a triangle wave input from the VCO. Without the triangle wave input, there is no output. That triangle wave is converted to a sine wave, and the module also provides a square wave with variable pulse width.

The VCO lacked a sine wave for cost reasons and the sine wave was provided by the sine/pwm module.

These modules came out in the early 70's and were designed as an entry point into modular synthesis when the only alternatives back then were university electronic music studios or others with deep pockets.


dvdsmoke

are these the right tip plugs? i've seen them in different sizes and i'm not sure
http://www.mouser.com/ProductDetail/Keystone-Electronics/6002/?qs=sGAE piMZZMv0W4pxf2HiV6YU8TCM0qP%252b6U57rsy7XWQ%3d

having a little trouble confidently locating the proper jack.

still thinking about... banananana sad banana


dvdsmoke

are these the right tip plugs? i've seen them in different sizes and i'm not sure
http://www.mouser.com/ProductDetail/Keystone-Electronics/6002/?qs=sGAE piMZZMv0W4pxf2HiV6YU8TCM0qP%252b6U57rsy7XWQ%3d

having a little trouble confidently locating the proper jack.

still thinking about... banananana sad banana


Kyhotay

I have had my hand slapped in the past re: mentioning things for sale in the wrong forum so I have no plans on doing that now. Besides, I haven't had the time to go through my collection of ORIGINAL PAIA PIN JACKS (BLACK & RED) or CV cables to even begin to suggest I might me able to help. Maybe if I get time this weekend I'll post something on that auction site.

On another note...I have been talking to Scott Lee about PAiA doing a remake of the 4771. For my refurbishing project I took the 9771, added their PS-60(?) kit for regulated 18V and designed a new panel for my synth.

I think these are some pics of what I did...


Rob_C

dvdsmoke wrote:
are these the right tip plugs? i've seen them in different sizes and i'm not sure
http://www.mouser.com/ProductDetail/Keystone-Electronics/6002/?qs=sGAE piMZZMv0W4pxf2HiV6YU8TCM0qP%252b6U57rsy7XWQ%3d

having a little trouble confidently locating the proper jack.

still thinking about... banananana :sadbanana:

That seems right, but pricey. You can find tip jacks under $1 each by searching for "tip jacks" on Ebay.


TheDegenerateElite

In my opinion, it's not worth the hassle to clean the old tip jacks if you are replacing them. The oxidation inside them is a pain to get rid of.

Here is info for brand new replacements. The jacks are threaded on the back and include a nut, so you don't have to use the old Tinnerman push nut/clamp things that the original jacks used.


These are the black jacks: 530-105-0603-1

http://www.mouser.com/ProductDetail/Cinch-Connectivity-Solutions/105-0 603-001/?qs=CgID%252bvbxand%2fGjoMDkTrJA%3d%3d


These are the red jacks: 530-105-0602-1

http://www.mouser.com/ProductDetail/Cinch-Connectivity-Solutions/105-0 602-001/?qs=ALatB1zlu3BPvkofx6it4A%3d%3d


And these are the red plugs: 530-105-0302-1

http://www.mouser.com/ProductDetail/Cinch-Connectivity-Solutions/105-0 302-001/?qs=%2fha2pyFadujy6KncAC13K3f6NTqLqru%252bbAlMIKo0TDKh%2fl2yNI htoA%3d%3d

Note that the plugs are a solderless type, but you can crimp and solder then as normal. You can get black also.

These are all made by Cinch and are the recommended replacement from Paia.


dvdsmoke

TheDegenerateElite
thank you!!!!!


valis

On ebay

http://www.ebay.com/itm/370911672543?_trksid=p2055119.m1438.l2649&ssPa geName=STRK%3AMEBIDX%3AIT

At some point I'm going to release some 4700/2720 compatible modules for the hell of it. I've had the plans for years. I'd like to start with a simple sequencer and a functional vca. Maybe I'll finally do it this year.

There's no money in it, I'd just like to contribute to the format.


TheDegenerateElite

Do it Valis. That would be excellent!


valis

Awesome a Wyoming wiggler!

One of these days I'll put some stuff out there, maybe sooner than later. I just always get sidetracked with other projects. I really just need to get some panels made somewhere.

As far as pin jack goes, I like to use banana to pin converters like these:

http://www.ebay.com/itm/Pomona-1432-0-Banana-Jack-To-Pin-Tip-Adapter-B lack-Used-Excellent-Condition-/221754226063?hash=item33a194f58f

Pretty handy. You can find them pretty cheap if you don't go with Pomonas.

.. Regarding power, Khyotay's setup is totally the way to go. Clean and new power. I have the old power distro in my only wired cabinet right now and it's a a hassle to add modules to a mostly full cabinet.

@ dvdsmoke nice job getting sound out of some modules. I really love the 2720 BPF and 4700 filter. Lofi but really cool. Great info by Rob_C

Fun stuff!


TheDegenerateElite

Indeed! There are not many in Wyoming....


dvdsmoke

hey everyone, thanks for all your help. this project is really coming along!

here's an update on my project status:
-received package from mouser today. i had ordered a bunch of tip jacks and plugs. keeping the bananas in the kitchen for now.
- received some 7660s for -9v in my mouser order today. got that power up and running! (should i be checking for anything other than -9v?)
- tested 2/4 modules that require the negative power. they seem to be working. (oscillator only makes sound when receiving voltage, is that normal?)

yeah yeah very excited.
remaining steps:
1) test two remaining modules (env follower and inv buffer)
2) calibrate individual modules
3) make ghetto case
4) make power bus
5) encase and connect everything
6) play
7) [optional step:] make/experiment with some DIY stuff for it

valis, i would love to have a sequencer for this. i think you should pursue it!

pictures soon, hopefully! weeeee! Dead Banana

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