Miniwave CV select PROM project – New 12/30/03

Here are a few photos of a the prototype module to apply control voltage selection for
the PROMs on Dave Hylander’s Miniwave PROM expander PCB. I am currently testing
the circuit. Once testing is complete, a PCB will be made available to fit on the top of
your expanded Miniwave module using Stooge brackets as shown. One neat aspect of
this PCB is that in addition to providing the voltage control circuit and a handy place to
mount the LEDs, it will also hold the "bank" and "wave" LEDs firmly in place from the
original Miniwave board. A separate regulated power line on the PCB will help isolate
LED switching noise from the +15 power line for all 18 LEDs. Lastly, an inverting op
amp will be provided so you have OUT(-) function on your Miniwave. The OUT(-) jack
is provided on the Stooge panel. When the PCB becomes available, you will find a link
here to Scott Juskiw’s site. Scott is doing the PCB layout and marketing of this PCB.
Click on thumbnails for full size photos:

 
This shows the position of the CV PCB on the Miniwave module. The location was chosen to allow all 18 (8 miniwave + 10 expander) LEDs to be mounted on a PCB.

You can see from this angle that three stooge brackets are used for all PCB mounting. And, stand-offs are in place to support Hylander’s PROM expander board above.

From the back side of the bracket, you can see I have used a 4-pot long bracket and I have cut the size down some. A 3-pot bracket could be made to work without cutting. But, a 4 pot bracket is recommended to use the Miniwave PCB mounting holes. Two new 1-pot mini brackets are used to hold the CV PCB.

This photo shows the protoboard mounting from the top. When the PCB is actually made, it will be slightly deeper and will fit closer to the panel to keep the LED leads as short as possible. Headers along the back will provide connections for power and the other PCBs,

From the side, you get a feel for how the LEDs will mount. Of course, the leads will be shorter, but the 90 degree bend provides a lot of flexibility in alignment when installing. A slight "over-bend" will assure that the LEDs are kept firmly in place on the panel.

Here I show my Miniwave PCB completed with panel wiring ready to be placed on the bracket. I like to bring some of the front panel wiring out from underneath the PCB to keep everything neat. The jack wiring (on the right of the PCB) gave me a nice place to secure my LED ribbon cable


Here’s what the completed Miniwave PCB looks like from the top. The only modification required to the PCB is to omit two resistors and install one jumper from S1-1 to S1-3 as you will not have an A/B switch. I also recommend not installing the Blacet supplied leaf spring ROM socket. This is where the cable will plug. It holds MUCH more securely if a machine socket is used. I already had mine installed before I realized this.

The Miniwave PCB is mounted on the bracket. The 3 of the 4 pots hold the brackets in place. Another pot is added to that task when CV PCB is installed.

All the loose ends of the panel wiring are completed. The yellow wire looking out of place is a temporary OUT(-) connection. Please ignore.

Once the CV board and the PROM expander board are installed, your Miniwave will look something like this. Of course, the CV board will be a lot nicer than my proto version. A ribbon connects the Miniwave to the PROM expander. A power cable connects up to both Miniwave and expander. The CV control PCB will get its power from a connection on the PROM board.

Here is a look from the top. I have a lot of excess ribbon cable length in mine going to the CV PCB. I will shorten this up when I get the official PCB. The CV PCB will have one ribbon to the Miniwave (for the LEDs) and one to the expander PCB. A small number of wires go to the front panel.

Here’s a look from the bottom. There’s a lot of stuff in there. However, great care has been taken by all involved in this project to make sure all the mechanical fit issues were considered.

 
Here is a photo of the completed module from the back. You can notice a couple of things. First, notice that the stock Miniwave PROM is not located in the socket John intended. Instead it is installed in the LIF socket. The ribbon cable connects to the original PROM socket. I already had my leaf style socket installed on the Miniwave PCB before I discovered that the connecting cable holds much tighter if a machine socket is used. I did not want to de-solder it and risk my Miniwave PCB. If you find yourself in this same situation, you can do what I did. I plugged a machine socket into the leaf socket and plugged my cable into that. It really works great. J


Here is the completed view from the front. I plan to change the LED colors on the final version – 4 red, 4 green for bank and wave, 10 blue or orange for PROM select. Notice you have two new pots for CV select of the PROMS. They function exactly the same as the Miniwave pots for bank and wave. Also notice the OUT (-) jack. That inverted out is a new feature for the Miniwave supported on either the PROM expander or the CV board.

This space below is reserved for the final photo of the competed module once I have the CV PCBs. Stay tuned. J

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