[ecir38]

EDIT: see this link  http://www.audiocircle.com/index.php?topic=44822.0 page 2 reply 17 for mod.



The Piccolo loading options can be changed by replacing the R1A-F resistors with a desired range for the particular cartridge you will be using. This has inspired me to come up with a way to accomplish this without any soldering involved. I think I finally came up with something that may prove to work out.

First the spacing (pitch) between the resistors needed to be determined, which is 2.54mm or .100”. I was only able to find one terminal block from digikey that had a 2.54mm pitch. The part # for this part is 277-1277-ND. http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=277-1277-ND



I went ahead purchased four of these for the heck of it when I purchased the parts I needed to build the Piccolo from digikey. Here is where I ran into my first problem. The terminal block fit the pinout on the pcb perfectly but as you can see below the pins were centered with the terminal block. This positioned the blocks on the pcb without an adequate amount of space to allow the resistors to be installed. 



I threw this on the side and proceeded on the assembly of the Piccolo. While cutting of the excess from the leads on the resistors that had been installed I came up with the idea that I could use this scrap material to make my own solder connection to mount the above terminal block. To achieve this the existing pins on the factory terminal block would need to be removed. The pins were removed with success which proved to be beneficial in more than one area.

First the screws need to be loosened all the way to allow the pins to be removed. A scratch all was used at the point on the figure below to push the pin out of place. Caution should be taken when removing the pin as not to have parts flying around.
     


Below are two pics of the terminal block with two of the spaces disassembled on the terminal block.




Below is a pic of the leads screwed in place.



The leads were bent the thickness of the pcb.



Below are the terminal blocks in place before soldering. Notice that for R7 and R8 that the leads on the back of the board are cut shorter than normal on one side and by modding the block to install it as shown allows adequate room to clear the R7 & R8 terminals on the rear of the board. Also notice that by removing the factory pin on the terminal block allows the resistor to pass through the terminal block which should make installing them easier.



Let me know what ya’ll think.

[ecir38]

I forgot to make note that this could be held in place with a small amount of hot glue on the sides. It is also possible to not use any hot glue, as long as you don't replace all of the resistors at the same time. When the block is soldered in place it  should be pretty secure. 

[hagtech]

Looks ok to me!

jh

[tubesforever]

I love your solution to easy loading changes.

I have a question....these are being loaded from the bottom of the pcb is this correct?

[ecir38]

That is correct. I guess it could be done either way as long as R7 and R8 are installed opposite of the terminal block.

[ecir38]

after soldering. The pictures make these parts look larger than they actually are. The reason behind that statement is although this requires no soldering to replace the resistors they will still be tricky to replace. I think that by precutting the resistors the width of the outside of the two terminal blocks and good pair of small hemostats will be needed especially if the pcb will be going in an enclosure other than the one recommended in the kits bill of material. The only thing i have to do know is figure out a way to label the pcb for referance when replacing resistors.

[tubesforever]

You know I have been looking over my Piccolo now for a few days, and my idea for a solderless resistor post is simply not going to fit the board at all.  Your solution is simple, elegant, and looks like it will work exactly as desired. 

I plan to buy some blocks today and do the same thing with my unit.  I might actually incorporate the blocks onto the back side of the C2 Piccolo case work so I can replace these without accessing the inside of the phono stage. 

Thanks for an excellent idea.

[ecir38]

I plan to buy some blocks today and do the same thing with my unit.  I might actually incorporate the blocks onto the back side of the C2 Piccolo case work so I can replace these without accessing the inside of the phono stage. 

Thanks for the compliments. Mounting them externally was something i never thought about and sounds like a great idea. If you were to do this by connecting them with hookup wire then mounting to the exterior i imagine you would have a larger selection of terminal blocks that may better suit that application.

Here is a link to the eclosure that i am going to use which shouldn't make changing them that difficult.
http://www.lmbheeger.com/products.asp?catid=27
Model# KB4-7

Check your email i sent you those pics.