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 Power supply questions 
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Joined: Thu Sep 03, 2015 10:56 am
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Post Power supply questions
I'm considering getting back into modular with a Paia Frac Rak case and I'm trying to untangle the power supply options. Here are my questions:

1. If I start with a single FR-7 and a MIDI2CV8, will the MIDI2CV8 power supply provide all the power I need for a rack full of modules, or should I add another power supply? If so, which one?

2. Do the first generation and second generation Paia Frac modules have similar voltage requirements? Will the MIDI2CV8 power supply work for both?

3. I have some modules I made from CEM chip-based circuit boards sold by Paia a long time ago. They are currently housed in a 4700 cabinet and powered from the 4700 power supply. If I adapt these modules to Frac and install them in this system I'm considering, will they work with the power supply for the other Frac modules?

4. Does the power supply recommendation change if I would like to include a Blacet module or two?

I expect the answers to these questions are somewhere on the Paia site, but I haven't dug them up yet. Thanks for helping to speed my learning curve!

Charlie


Sun Sep 06, 2015 8:40 am
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Joined: Sun Nov 09, 2008 2:49 pm
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Post Re: Power supply questions
Hello Charlie.

1. If I start with a single FR-7 and a MIDI2CV8, will the MIDI2CV8 power supply provide all the power I need for a rack full of modules, or should I add another power supply? If so, which one?

...and...

2. Do the first generation and second generation Paia Frac modules have similar voltage requirements? Will the MIDI2CV8 power supply work for both?

The MIDI2CV8 is the power supply for the complement of modules in the P9700S (9710, 9720, & 9730). It has the same four-wire DC power connection points (+, G, SG, -) as the other modules and power jumps from one module to the next with the basic modules having two connection areas for accepting the power and passing it on through. The minimum Amp rating of the 12V AC transformer used with the MIDI2CV8 is 1A (1000mA). 1200 to 1500 mA is even better. MIDI2CV8 uses a voltage-doubling rectifier for unloaded, dual-polarity 18VDC supplies. With the 1A transformer to the MIDI2CV8 and the load of the other three modules in a P9700S the DC passed along is about 16V. The modules take this unregulated DC power and on-board regulate it to twelve volt supplies. The supplies from the MIDI2CV8 are at their limit on the 1A transformer -- with more Amps, more power can be tapped, but the FR-7 chassis is full. If you are planning an expander system in an FR-7, it is best to have a second power supply.

The first and second-generation 9700 series modules can operate from regulated fifteen volt power supplies; however, for the best results, the first modules in the series should have the power supply input coupling resistors bypassed or replaced with wire.

For the most power in an FR-7, the 9771-15 is recommended. It provides up to 600mA on the positive and negative 15V DC supplies. It has 12 power connection areas and this is useful with the second generation 9700 series modules which only have a single DC connection area (each module wires back to the supply rather than the pass-thru arrangement on the first generation modules). It occupies one of the ten single FR-7 spaces.

The 9770R-15, also a regulated, dual-polarity fifteen volt DC supply, can be mounted in the mounting ear area of the FR-7 chassis when fitted to the FR-PWP option, leaving all ten single spaces available across the front of the FR-7. With the 16VAC/800mA transformers we presently include wiht the 9770R-15, it is good for up to about 300mA per supply -- plenty for a system of 9700 series modules and in most instances, a mix including other brands too. There are only six power connection points on this supply, so power connector wiring must be doubled-up or, a piece of 0.1" spaced strip-board used to extend the taps.

3. I have some modules I made from CEM chip-based circuit boards sold by Paia a long time ago. They are currently housed in a 4700 cabinet and powered from the 4700 power supply. If I adapt these modules to Frac and install them in this system I'm considering, will they work with the power supply for the other Frac modules?

The EKx-series modules which featured the CurtisElectroMusic ICs were designed for fifteen volt supplies, so if you didn't make any changes to them for use on the nine volt supplies of a 4700 series system, it will not be a problem switching them over to an FR-7 with the fifteen volt supplies.

4. Does the power supply recommendation change if I would like to include a Blacet module or two?

No, you would just need to connect the wire with the connectors used by Blacet modules to the PAiA power supply connection areas. PAiA modules use two grounds with return to a single point on the power supply, G and SG. G is used for circuit sections with power supply filtering and toggling/switching or ones that can result in currents that can result in noises when they intermingle with audio, and, SG is reserved for the audio circuit-sections. The Blacet's have two grounds, but not a distinction for one or the other. Use a separate wire for each, with them beginning at a SG point on the PAiA Supply.

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Scott Lee
scott@paia.com


Tue Sep 08, 2015 11:16 am
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