Patchbays - Wiring Harnesses and Molex issues

I started working on the patchbays. I found 2 gently used 96 point TT bays in Nashville. I cleaned them up and de-soldered the original cable ends. I don't have a heat gun but I do have heat shrink in my "care-package"!... go figure. I will use shrink only when necessary...

I have the first mic snake wired up on Mogami 8 pair. The Molex pins on the mic inputs to the console are not removable. (14$ later for a molex tool... unusable) so I have to buy 3 hole 0.093 Molex conectors.
I will rewire them with some single Mogami I have. Just enough for 16 inputs to the bays.

My eyesight is so bad now that I have to use my readers to see the solder lugs.

I built a holding jig to hold the bay at the right angle.

I got Susan to assist me in clipping out the old mogami!

 

16 Inputs - Ready!

I have reworked all 16 IO modules. It has taken about a month and a half. about 1.5 hours each day.

Tangent 3216. circa 1979 Recording Console that I am rebuilding.
All modules have been reworked and I am testing audio through the system.
There are a few problems remaining in the metering; a VU and LED meter problem.
Ready to start the patchbay!

I powered it all up and it sounds great!. I tested all the mic pre's and tape inputs and outs.
Then I did tests of the submaster busses. I have one VU meter acting up on #10, I will torubleshoot it.
A 4016B Comparator a TL084 opamp and 3- LM336's for the LED drivers. the Peak Reference transistor pair is fine... and another VU modeul works perfectly when swapped out...


The Master Module is ready.

I put in the TB Oscillator module and it is working to all busses except 16. I think it is the finger module.

TB Osc Module - Peak Ref adjust (+15V)

TB Osc Module - Main board - ICL8038 VCO . I have a mod idea!

I read the datasheet on the ICL8038 VCO IC. The Tangent 3216 provides a sine wave output to the MIX, CUE, or BUSS. I read that the IC also supports Triangle and Square waves on pins 3 and 9 respectively. I think I will pull those out to the patchbay for a handy tone reference jack! Just add a resistor to ground. I will try 1K, 10K and 100K. Cool...

I also had time this week to build some shelves that I promised Susan long ago... came out pretty good! lots more room for storage now... ~30$ of wood and 3 hours...

Metering - LED and VU

Metering. The console uses LED meter for each channel. It can be globally switched between Peak and VU modes.

IO Modules - 9 of 16 Completed!

I have

Designing the studio...

I have been working on the console off and on after work in my spare time.
I bought it Oct 1, 2011.It is now late Nov and I am on vacation this week. I am setting up this blog...

I have been using Google Sketchup to design things. I really like it. It is very easy to use once I got used to it.
I even use it for work to design and plan projects.

And its is FREE.

I am on a zero budget!

Here are some of my sketchup ideas for the studio... Someday...

I even created a Tangent 3216 model. It needs some tweaking still...

I drew this from memory. It was pretty close to the real thing.

I wish I had the Studer. Google had a good model so I grabbed it.
I will find a good multitrack solution someday...

Troubleshooting 101 - Logic - In Circuit...

The circuit boards do not have a silk screened layout on them. So it is hunt-n-peck to find what you need.
The schematics I have with the console are like the dead sea scrolls... deciphering them is taking quite some time. I scanned the really illegible ones and blew them up. Since this is my console I marked up the circuit boards with my notes, etc...

Submaster amps. 4011 nand gate. solo fet's.

Created this to help me find my way around the IO Module.

My friend from work is an electronics person. He loaned me his ESR meter. I checked all the caps and most were fine. I replaced any bad ones that were off the scale. I did not know that much about ESR and I am glad now that I do. It even works in circuit. His was a kit he got at: ESR Kit

Troubleshooting 101 - Master Logic.

The console uses an X and Y logic buss to set up the signal path. The modes are INPUT, TAPE, and MIX.

Using the switching logic you can place the Mic Pre or the Tape In to the Chamnel (EQ, Phase, Cues, etc) or the Left Right Monitor Mix.

The Input Output Modules (IO) use a CD4011 quad CMOS Nand gate to define the logic states from the X&Y busses.

The output of the logic controls JFETS that are placed to either allow or block the signal path from the mic pre or tape inputs to the channels. When the JFET has a -15VDC on the gate it turns on the FET and either allows signal or shunts it to ground.

What really confuses me is that the circuit is using negative logic. In other words VSS is not +15vdc as in normal cases. VDD is -15V. So a "true" or "1" state is actually 0vdc ground. a "false" or "0" is -15vdc.

Here is a more in depth example below. The Tape Input flows thru the N-channle FET Q13 if S2C is at -15 logic state. And in this state Q11 shunts the input to pin 2 + input of the LM351 opamp. effectively to ground... "muting" that input to the Master LR 2 mix...

Now on to more troubleshooting....