Hi Xmax,
There are some big differences between the VCA and the Ultimation console fader system. Although the Ultimation is "retrofittable" on VCA consoles, these systems are completely different and will need a change to all of the core components involved with fader operation (computer I/O cards, computer lights/switches - CA bus card, channel vca cards, fader bus cards and the faders cartridges). You may find some similarities on signal levels but that's needed in order to maintain compatibility with the console operation levels, but they are different and behave differently. Because of this you can't bypass the computer like you do on the VCA fader consoles, with bypass links. It just doesn't work this way. How you can do it? We'll get there...
While developing the SSLMixed Computer we've been able to go deeply into these differences, so maybe I can throw some light into this topic.
I have just gone through the manuals and schematics to try to answer your question with accuracy, so please bear with me if I make any incoherence during the explanation.
First thing you need to know is that these faders have active electronics, both for control and motor servo driving (this doesn't exists on traditional VCA consoles). These functions are assured by each of the 2 electronic cards present on the fader sandwish. The functions of the fader are digitally controlled, these change modes of operation, control leds, vca grouping, touch sense detection, etc. This digital communication is done by an 8 bit read/write bus with the CA computer (SSL Computer), that travels through the standard S14 cables that connect from the console to the computer. Although without the computer you'll not be able to control the faders, you still need to have the Electronics PSU on (-+5v rails), since all the electronics of the fader are powered and driven by it. The electronics also power the analog rails on the fader with -+15v. This means you'll always need the SL668 PSU (electronics psu) ON in order to be able to have working faders and drive audio through it (on ultimation audio goes through the fader wiper).
The second PSU (Motors PSU) is only there to drive the faders motor servo cards, and this can be off if motors operation is not necessary (this only works with computer return - CA RETURN - to drive it through the motor servo card on each fader). You can have this PSU off either in motors on or motors off (vca) software modes. In the first case faders will not move, but audio will still pass through the fader wiper. (I often leave it off just to make the balance, as soon as I start automating I turn the PSU on). On the latter case, audio goes instead through the VCA card, voltage is controlled by the fader wiper (similar to VCA consoles). - Default operation fader status is MOTORS ON on startup. - schematics for the 353 card on ultimation service manual shows how this works.
Just as a curiosity, there are some situations during Ultimation operation in MOTORS ON mode, which turns motors off without switching to MOTORS OFF/VCA mode. In this situation audio continues to pass through the fader but motors are disable, thus fader won't move.
CUT is also detected and controlled digitally. Although the VCA level will still go up to 7.5-10v to indicate the CUT was pressed (on the VCA card - this the same with the VCA fader system), this is then converted by the fader logic card to a digital ON/OFF and sent to the computer via the CA bus. And this is how the computer detects and controls the CUT automation. - schematics for the 352 card on ultimation service manual shows how this works
Now with the grouping all indicate that it should work in MOTORS OFF/VCA, but we have found out that with the MOTORS ON the CA computer does some internal offset compensation to prevent group faders to drive slave fader motors over the top. This protection is needed because faders are moving and can overshoot the fader track. This is obviously not needed for non-moving fader operation, so grouping should still work normally.
UPDATE GROUPING:
The 353 card is not a straightfoward easy read. At this stage we believe there's no feedback to the audio path on the 352. If this is true, the only way to have group faders is with DC GROUP affecting the servo motor. This will move the fader having in consideration the DC GROUP voltage (this is what happens in normal operation) and retro-actively compensate the audio for it. This is how group faders work on ultimation.
That being said.... if we are correct at all, it seems group operation is NOT possible without fader movement, thus it might not work at all without the computer.
But it is worth a try, by turning on the motors PSU last and see how it goes. - Paavo just confirmed that indeed group operation is not possible without a computer.
UPDATE:I forgot to mention than while VCA systems loop the VCA level through the computer, this doesn't happen on the Ultimation systems. And this is why you need to fit bypass links on the VCA systems, or else you'll be breaking the loop and faders will not work. With Ultimation systems the VCA/Audio level is all determined through the fader wiper position. The fader wiper is either controlling the Audio Level, if in MOTORS ON mode, or controls the VCA level when in MOTORS OFF/VCA.
Now, in MOTOR ON mode the fader wiper level is sent to the computer and looped back to the servo card on the fader cartrige (CA RETURN + and -). This value is then summed with grouped DC level and used to drive the motor to move the fader to the correct spot. When the fader reaches the correct spot, the audio level is restored.
Since there is no computer in a situation of failure you're only letting go the DC motor driving, but the audio level is still represented and controlled by the fader position (because this doesn't loop through the computer), so you still have control by manually moving the faders.
In VCA mode, I am convinced (would have to dig deeper in the schematics) that it behaves very similarly to the VCA systems, with VCA level truly looping through the computer, and this is why default electronics mode is MOTORS ON and CA FAIL mode is also MOTORS ON mode but with logic off, which means motors control is shut down. I would say I am almost sure you can't have VCA mode without the computer, also because you don't have any way to change the mode without the computer and with electronics shutdown.
--------
The only trick now is how you put motors off when the computer is not working, and there is a hint on how this works in the power supply section on the ultimation service manual:
The SL668 (Electronics) PSU has an internal watchdog circuit that detects computer failure. When the computer is on, it will generate a pulse signal CA_MON (strobe) that refreshes the internal watchdog electronics preventing CA_FAIL to kick in. When CA_FAIL is detected (for instance if you turn computer off) the PSU will reset all faders into "non-CA mode", which will set MOTORs OFF (this is not VCA mode). Actually what happens is that as soon as the strobe signal fails an IC kicks in pulling down the logic +5v voltage rail to near 0v and shut down the fader logic. This will assure that the audio rails will still work and you have fader operation (group DC is also fed by the +15v audio rail and this is why grouping should still work). - unfortunately in this mode you'll not be able to use the VCA flavor of MOTORs OFF mode, since this mode is enabled through the computer/CA bus interface.
This strobe signal is carried out from the CA computer to the back of the SL668 PSU (electronics PSU) through the S41 cable which has to be connected for this to work (check for this connection). Also make sure the LK5 jumper is set in the SL668 PSU to enable the watchdog circuit, since without this the circuit will be indeed disabled. If this is set you should see the CA_FAIL led on the front of the PSU lit when the computer is powered off (which is your case).
S41 cable pinout
Another important thing, as you can see on the diagram, is to have the GROUPS 1-8 S14 cables loop through the SL668 power supply S14 connectors on the back (console -> 668PSU -> computer). This has to be connected in order activate a mechanic relay which hard-bypasses the console main fader when the CA_FAIL is detected. The main fader is the only fader which is fully analog and its bypass is handled in the same way as the VCA consoles, with the only difference that the bypass link is already built-in on the SL668 PSU and triggered by computer failure.
I think this is all that you need to understand and configure bypass mode on your console.
Summing up:
- You should have all S14 connected to the computer, as normal (do not fit any bypass links or change the configuration other than needed to fit these instructions)
- You should make sure S41 is connected to the back of the SL668 PSU
- You should make sure LK5 jumper is fitted on the SL668 PSU. - You can see if CA_FAIL is being detected by the CA_FAIL led on the front panel of the PSU.
- You should fit the GROUP 1-8 S14 cable loop on the SL668 PSU to assure main fader relay bypass.
- Power up the console
- Power up the SL668 PSU
(do NOT power motors PSU) - read GROUP UPDATE
Good luck! And I wish you a awesome 2015!
Cheers,
Artur
