Luny Tune
Well-known member
Here is the documentation for the project with assembly notes:
http://www.tunetown.dk/download/LA-IV.pdf
Including a BOM, drawings of the board and a guide to connect the switches.
Missing is some pics from a stuffed board I made. I can't find the damn cable to go between the camera and the computer. I'll update the pdf with them of course when I find the cable later.
And here's the best manual for the li'l devil:
http://www.tunetown.dk/download/LA-IV%20Complete%20Manual.pdf
Including test and adjustment procedure.
Our version is the schematic on page 31. Numbers on the board for wiring corresponds with the numbers in the schematic so just work with that.
This version differs from the original schematic in the following ways:
1. RCA4136 quad opamps have been replaced with the TL074 quad opamp making the board pin compatible with even more esoteric quad opamps like the MC33079. (Pinout does not match the schematic. Refer to the datasheets for the two types of quad opamps when tracking errors. I will update the schematic with the pinout for TL074 and put it in the pdf-document at some point.)
2. Optos from the original as ordered from JBL as replacement parts can be fitted right into this board effortlessly, but with a few and easy modifications it's also compatible with other optos like the Vactec Vactrol VTL5C4/2.
3. The 2n6716 and 2n6728 transistors have been replaced with BD135/136 or BD139/140 transistors.
4. The output transformers I've tested are: OEP A262A2E and Cinemag CMOQ-2S which both work just great. I have both installed in two LA-4's and I don't prefer one over the other. I'm sure the Lundahl LL5402 will work just fine too as these three are interchangable in many designs.
Credits:
Thanks to Rasmus Fris for helping out with the prototype.
Thanks to Jakob Erland for great inspiration and general help.
Thanks to David "Craptical" Carlsson for kind assistance.
http://www.tunetown.dk/download/LA-IV.pdf
Including a BOM, drawings of the board and a guide to connect the switches.
Missing is some pics from a stuffed board I made. I can't find the damn cable to go between the camera and the computer. I'll update the pdf with them of course when I find the cable later.
And here's the best manual for the li'l devil:
http://www.tunetown.dk/download/LA-IV%20Complete%20Manual.pdf
Including test and adjustment procedure.
Our version is the schematic on page 31. Numbers on the board for wiring corresponds with the numbers in the schematic so just work with that.
This version differs from the original schematic in the following ways:
1. RCA4136 quad opamps have been replaced with the TL074 quad opamp making the board pin compatible with even more esoteric quad opamps like the MC33079. (Pinout does not match the schematic. Refer to the datasheets for the two types of quad opamps when tracking errors. I will update the schematic with the pinout for TL074 and put it in the pdf-document at some point.)
2. Optos from the original as ordered from JBL as replacement parts can be fitted right into this board effortlessly, but with a few and easy modifications it's also compatible with other optos like the Vactec Vactrol VTL5C4/2.
3. The 2n6716 and 2n6728 transistors have been replaced with BD135/136 or BD139/140 transistors.
4. The output transformers I've tested are: OEP A262A2E and Cinemag CMOQ-2S which both work just great. I have both installed in two LA-4's and I don't prefer one over the other. I'm sure the Lundahl LL5402 will work just fine too as these three are interchangable in many designs.
Credits:
Thanks to Rasmus Fris for helping out with the prototype.
Thanks to Jakob Erland for great inspiration and general help.
Thanks to David "Craptical" Carlsson for kind assistance.