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CPS 450 for Delta 200 board
Old 11th July 2014
  #1
Gear Nut
 
🎧 10 years
CPS 450 for Delta 200 board

I picked up a CPS 450 to replace a dying CPS 150 for my Delta 200 board. I am looking at the specs for the two psu's and can use help with one aspect of it. The 450 has a separate 0V for the +48v from the other rails (+/-17V etc) whereas the 150 has a single 0V wire for 48v and the +/-17V.

Do I connect the 48V ground pin (#6) to the 17V-etc ground pin (#5) in the CPS450 connector?

Thanks for any help!

See the lists below for more info:

CPS 450

1 +17V
2 + 7.5V
3 -17Y
4 Chassis Ground
5 +17Y, -17V, +7.5V & -7.5Y Ground
6 +48V Ground
7 +48V Ground
8 +24V:
9 - 7.5Y
10 +48V
NOTE: Pin 6 is reference to Pin 10 – I don't know what Pin 7 is doing.

CPS 150

1 Protected Earth (Green/Yellow) Chassis
2 0v (White) CONl-2
3 +48v (Grey) CONl-4
4 +17V (Brown) CONl-1
5 -17V (Blue) CONl-3
Old 11th July 2014
  #2
Lives for gear
 
🎧 15 years
Hi
Yes for 'convenience' link the ground of the 48 to the ground of the +-17 volts.
Having the ground of the 48 separate (as the 450) allows this ground to be connected to the Chassis (and hence pin 1) INSIDE the mixer. This is the way it SHOULD be done but many simply link it to the 'common' (as the 150).
This is obviously a bit more work to actually do this as you will probably need to change the connector on your desk.
Over the years (proliferation of nasty RF signal devices) CORRECT ways of connecting the phantom power are increasingly important. From the microphone's point of view the XLR pin 1 is where the GROUND of the 48 supply should be connected although to make things more confusing any 'filtering' of phantom should also be referenced to pin 1 (chassis) on the mic.
So, your choices are 'quick and dirty' or thoroughly check the wiring and make it 'right' which could involve you in quite a bit of effort.
Matt S
Old 11th July 2014
  #3
Gear Nut
 
🎧 10 years
Hi Matt - thanks for your (fast) help.

Quick and dirty for now though I'm curious about the modification you describe. Would the idea be to untie each mic input's pin 1 from the card's common ground and then create a ground bus that ties them to the chassis. And then connect the spare wire in the psu multicore (there is a 6th unconnected wire in there) to the chassis of the desk at one end & the 48V ground at the other?
Old 12th July 2014
  #4
Lives for gear
 
🎧 15 years
Hi
A lot will depend on EXACTLY how it is done now and would be different on other desk layouts/wiring.
Ideally Pin 1 on the XLRs should go to the metalwork directly (half inch wire link or similar).
Take the 'ground' of the 48 supply to chassis (pin 1) at the nearest XLR to the power connector.
On the basis that the phantom supply has a capacitor 'filter', typically 10 or 47uF cap and a resistor may be 100 Ohms, the negative of this cap should NOW go to pin 1 (ONLY) on the respective channel XLR. This is where the 'extra' work may come in. The usual 6K8 resistors can probably stay as they are.
The existence of 100 Ohm (or thereabouts) resistors, together with the 47uF capacitor 'filtering' each channel will reduce any possible 'hum loop pickup' which may occur in the physical loop formed by the 48 volt bus and the chassis grounded pin 1's of the XLRs. The fact it works well enough in it's existing format suggests you do not need 'paranoia' about this!

Matt S
Old 12th July 2014
  #5
Gear Nut
 
🎧 10 years
Thanks again, Matt ––– not paranoid not paranoid not paranoid

I have some other work to do on this desk so for now I'll go with the jumper in the connector but save your post for reference.

Old 28th February 2021
  #6
Lives for gear
 
White Falcon's Avatar
 
🎧 10 years
I’m going to do the same here, and I need to do it ”quick and dirty”.

I want to desolder the cable inside my CPS-150 and solder that into my newly acquired CPS-450.

But what goes where? What to do about the 0V that’s not present in the CPS-450? If someone could help me in a “for dummies” way I would be extremely grateful!

I’m attaching some pics of the CPS-150 connector. I want to know what voltage/ground from the CPS-450 I should connect to pins 1 - 5 on the CPS-150 connector.

Thank you!
Attached Thumbnails
CPS 450 for Delta 200 board-27554656-2c75-41ae-825e-7f100e844879.jpg   CPS 450 for Delta 200 board-e9b51ef0-1127-4767-b779-5df660ea51b5.jpg  
Old 28th February 2021
  #7
The console has one power ground and one chassis ground. Connect power grounds together like in the 5 pin.
Old 28th February 2021 | Show parent
  #8
Lives for gear
 
White Falcon's Avatar
 
🎧 10 years
Thanks! So 5, 6 and 7 together from CPS-450 to pin 2 on the CPS-150 connector?

Last edited by White Falcon; 28th February 2021 at 08:39 PM..
Old 3rd March 2021
  #9
Lives for gear
 
White Falcon's Avatar
 
🎧 10 years
Can you gentlemen confirm this:

CPS-450 To CPS-150:
1 to 4
3 to 5
4 to 1
5 + 6 + 7 to 2
10 to 3

CPS-450
1. +17V
3. -17V
4. Chassis Ground
5. +17, -17, +7.5, -7.5V ground
6. +48V ground
7. +48V ground
10. +48V

CPS-150
1. Protected earth (Chassis)
2. 0V
3. +48V
4. +17V
5. -17V

As I don’t need the +24 and +/- 7.5V rails in the CPS-450, can I pull the fuses for those voltages in the PSU so it doesn’t have to work hard(er) to supply them? Or maybe it doesn’t matter as there are no load?
Old 4th March 2021
  #10
Lives for gear
 
White Falcon's Avatar
 
🎧 10 years
Old 1st April 2021 | Show parent
  #11
Lives for gear
 
White Falcon's Avatar
 
🎧 10 years
It worked.
Old 2nd April 2021
  #12
Lives for gear
 
🎧 15 years
Hi
As the 24 and +-7.5 rails are not being used you could pull their fuses but it won't make a significant difference to the amount of power taken by the supply in general. Possibly 1 or 2 watts at the most which considering the hundred watts (VA) of the main audio rails is not important.
Matt S
Old 2nd April 2021
  #13
Some of these came with National 3 amp regulators, some came with Linear Tech 5 amp regulators. The 10,000 uf mains caps are too small and most are bulging by now. I use 33,000/35V caps there and 1000 uf secondary.
Old 3rd April 2021
  #14
Lives for gear
 
White Falcon's Avatar
 
🎧 10 years
Cheers, gentlemen!

I left the fuses in place as I also didn't think it would make a lot of difference. I looked long and hard at the caps and rectifiers etc. But none were bulging and no components looked cooked.

I think that the new PSU really made a positive difference in sound quality, and the mix bus noise became slightly lower. I now read -100 in Totalmix on the Delta 16s mixbus with master faders up. The CPS-150 was around -97.
Old 3rd April 2021
  #15
Lives for gear
 
🎧 15 years
The trouble with 'just looking' and messing about with random things is not the way to actually diagnose and repair equipment properly.
You make a claim that 'noise' is now 3dB different. Over what bandwidth and rectifier characteristic or weighting for the noise filters. And what exactly was the noise that has supposedly reduced?
Was it 'wideband' hiss, or mains frequency and harmonic artifacts?
Matt S
Old 3rd April 2021
  #16
Lives for gear
 
White Falcon's Avatar
 
🎧 10 years
Matt, I really respect you and all the knowledge that you (very generously) spread around here so people who aren't EEs or can afford one get the help they need.

However, this was not a repair, but a modification. I measured all the voltages in the supply before I even started the cable modification to make sure nothing needed to be fixed first. As soon as I had soldered the cable and hooked it up to the desk I measured all the voltages again, waited a couple of hours and measured again. I then calibrated the rails carefully, waited, measured, listened, waited, measured and put the lid on.

Because nothing was broken, nothing needed to be fixed. Though many times I have found many faults by just going over the circuit bord on broken gear with a magnifying glass (and lots of patience, some whiskey and BBC World Service in the background). So "just looking" has worked many times over here. And of course I always measure and scope things as well (if I have to).

I don't have much fancy equipment at home, just a scope, multimeter, lab supply, etc. And I use RMEs DIGIcheck as I find that's all I need for simple measurements.

I measured the noise with DIGIchecks: Bitstatistic & Noise module and used the RMS (dbA+3) value.

I also looked at the noise amplified by 50db (in Cubase using Voxengos SPAN Plus) for the CPS-150 (screen shot) and compared that to the spectrum for the CPS-450B. And it was 60Hz with its additional harmonics around 100, 200 etc. that had been reduced.

I'm sorry that I didn't write this in my previous post, and I'm also sorry if this is the wrong way of measuring the "noise" and doing my random thing.

The very subjective value: "positive difference in sound quality" I used myself for. So I would not trust that too much

Again, I wish I had the money to send all my Delta stuff to Mr. Williams for modification, repair and upgrades. I wish I had studied electrical engineering at university (I studied molecular biology) so I didn't have to ask about things like this. I also wish I could go back in time to marry Kate Bush when she was 25 and buy all the Apple stock I could lay my hands on. But reality is what it is, so I do the best I can thanks to you, Mr. Williams and many others on this forum.

But all ended well; I'm using the desk to make music and that's the most important thing, I think

Now, off to drink some whiskey and listen to the BBC World Service!
Old 4th April 2021
  #17
I have a 450 in now and -17 went down. Rectifiers test good. Caps are bulged. After removing the pcb the trace from the transformer connector to the fuse is burned up and gone. The fuse is still good. The trace worked as a fuse and the fuse worked like a trace. All caps are now replaced (33,000 uf mains) and the new LM338 reg is going in.

Moral to this story, look underneath everything.
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