Built a custom D8B external power supply

[Y-my-R]

I have no clue about the power supply related stuff... but are you sure that the DB25 cable between the console and the rack unit is transmitting data in the direction from the console to the rack?

Did you use an extended cable for that, too, already, or still the shorter one? If you haven't tried yet, I'd switch out the DB25 cable first (even IF you're still using the same one as before... could be an odd coincidence), to see if it makes any difference.

It could of course still be the power supply... but this seems to be the easiest thing on the "process of elimination" list of things to try.

Best of luck to make it to the finish line, soon!

[RJH_MUSIC]

Last night I ohmed out the bfc on a working d8b. All the voltages are the same accept for the +/- 5 and sense. On the good console they are rock solid at 5.3v and do not fluctuate. So I think the problem is the new 5volt switching power supply. I do not understand that though because while it explains the pantothenic problem, it doesn't explain the fader motor problem I think. Going to try a different 5vdc power supply next.

[RJH_MUSIC]

Good point about the data cable. I did not think of that. I used the original cable and extended it with a new one I built to make it 40 feet long instead of the original 15 feet. I wonder if I did not plug the the data cable coms into the motherboard correctly. I will look at that.

[RJH_MUSIC]

To clarify, I used same data cable, db25, but I extended the BFC cable by 25 feet.

[RJH_MUSIC]

I still think the problem has to be related to the 5 v supply. I verified that the com ports are connected properly. So all of the original parts from the f8b cpu are in the new case with the exception of the 5v switching power supply, so I think the has to be there. Now going to try the other 5v supply I have to see if it will work.

[RJH_MUSIC]

Okay I am totally stumped. Switched out the switching power supply with the original LPS-152, resulting in all of the original d8b parts being used and console still won't boot. Interesting note. The the sense connected, the console won't even power on. Switched out LPS still no affect. Swapped he console with another one, no difference. Tried console with original CPU works. Turned my attention now to switching out 5v supply with original one recommended by Weiritz. No change. So I am left with only one possibility - the only thing different when I connected up all original parts is the length of the cable. And that may be why the sense connection inhibited the console from booting. During A normal boot up the 1st thing that happens is the Solo light blinks as the console is booting and it will say please wait loading host. After the plugins are loaded and it sees the MFX and UFX cards there is a momentary pause. Following that in a normal Boot up all of the meters Flash yours Flash as if the audio circuit is being tested or initialized. Following that all of the Fader's jump to 0 or move to the last known position depending on how You have that set in the OS. So with the new power supply that I built everything happens except the meter Flash and the fader movement at the end of the boot of process. So as a last resort I'm Going to reverse the process by which I extended the cable by 25' and go back to the original cable length then I will hook it backup and see what happens.

I could have sworn that I've read in a post somewhere that people have successfully extended the length of the cable so I don't understand why that would be the problem but it seems to be the only thing left to check. As I stated before I've ohmed out the cable several times and it has all of the correct voltages. The only other Possibility would be the jumper that weirets described as having to be placed on the control board within the console. I did not do that step mainly because I'm using all of the original parts from the D8V with the exception of 50 power supply. Any thoughts would be greatly appreciated.

[arjepsen]

The jumper is for the 12V "motor" grounds. This was originally connected to grounds back in the cpu-unit.
I'm still messing around with the power supplies, and atm. I have the M-gnd connected to the other grounds through a 100R resistor, to a have a bit of seperation. But there are a couple of places - one of them on the brain board, that has a 7805 regulator, that supplies 5V to some circuitry, regulated down from the 12V. If the ground connection isn't there, I don't think the desk will work right.
Check all the voltages after you turn the desk on - are they still were they need to be?
Check the data-cable is well connected.
Smack it with with a rubber chicken a couple of times, while doing the hoola....

[RJH_MUSIC]

I think I will try the chicken? The 12V is coming from the original Linear Power supply board via the AT Power Supply. I checked all the voltages on the cable at the BFC end and at the power Supply ends, and they are all correct. What leads me to believe it might be related to the Cable length is that when I hooked everything up using all the original d8b power supplies, it still would not finish a normal boot. I had to disconnect the sense outputs from the LPS-152 power supply that go to the Linear Power Supply board just to get the console to power on. That tells me it cannot sense the length of the cable possibly because it is too long. I extended it from 15 feet to 40 feet. I do notice that it the 5v power supply puts out anything under 4 vdc, the desk won't power on, but I tweaked it to 5.4 v which is exactly what the working unit ohms out at. Interesting note which also supports cable length too long is that the sense outputs are less than 5.4v. I have to tweak the 5v to somewhere around 5.6v - 5.8v to get the sense output to at least 5v. Tonight I will shorten the cable back to it's original length and see what happens. The Data Cable I think is okay because I can control the Pan-Pots on the console with the mouse. But turning the physical pan-pot has no effect. And yes, I need to check all my grounds. If everything is still connected through the CPU unit, then i should not have to worry about any ground jumpers, correct?

[arjepsen]

I would be very careful about going much over 5V.
I'm actually speculating, that there wont be much fluctuations in the 5V when operating the desk - I assume it's more a matter of what FX and I/O cards are installed.
Without remembering preciesely, I have this gnawing thought in the back of my head, that states that some of the circuitry is having specified max of 5.5V

[Jondav1120]

The issues you are seeing with the Faders and the Vpots not functioning are likely caused by the 12volt motor supply ground not being referenced to the digital (5volt) ground. Both the faders and the Vpots use separate 5v linear regulators on each board to provide a stable reference. There is also a regulator on the brain board that provides a reference for the A/D convertor. These regulators are fed from the 12v supply, BUT referenced to the digital ground rather than the motor ground, so there needs to be a connection somewhere between the two grounds. Quite where this connection is on the stock D8B console and CPU is not clear from the schematics, but it must be there!!
Ralph's instructions for the console power supply show a link between J201 & J101. These are the motor and digital grounds, so I'd guess that the grounds on the stock setup are connected somewhere within the CPU.

Edit: Having read through the thread again, arjepson noted the above as well. He comments that:

I have the M-gnd connected to the other grounds through a 100R resistor, to a have a bit of seperation.

As the only current that would flow through the resister would be the ground currents of the regulators, it will not be much (5-6mA per regulator at a guess). If you want to be able to use the console with an original CPU, I'd join the digital (5v) and motor (12v) grounds in your new CPU. Joining them inside the console would work , but if you were to go back to an original CPU with the grounds joined in the CPU as well, you will run the risk of introducing noise into the digital ground from the motor ground.

Hope that helps

John