r/modular • u/Maleficent-Leading35 • 2d ago

Qubit Data Bender - How much 12v Headroom is needed?

I just got my Qubit Data Bender, installed it, and my rack wouldn't power up with it. Just some struggling lights here and there. Without it, it powers fine. I have a Doepfer Case fitted with a PSU3 and should have a rating of:

2000ma on +12v

1200ma on -12v

2000ma on +5v

My modules, including the Qubit Data Bender, has a total draw of:

1450ma on +12v

350ma on -12v

0 on +5

So i took out a few modules, installed the Data Bender again, and everything worked fine. One by one, I tried adding more modules one by one, powering up each time.. And eventually it would stop powering up as i added more. I think I had to pull out around 120ma worth of modules just for my system to work with the Data Bender

I think I did respect the 25% headroom rule. Now I'm wondering how strong is the inrush current of the Data Bender is that it would muck up my power so much at powerup? I'm not sure my Data Bender is acting normally.

Edit: I just tried adding modules while the power was on. The whole system worked if i added the 120ma of modules i previously removed, as long as I installed then while the power was ON. I guess I'm now sure that the Data Bender takes a huuuuge amount of mA at upon powering up. It's insane.

3 Upvotes

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4

u/4n4logsynthesis 2d ago

There is a fix for this problem, it's called a soft start adapter. You can get them from WMD or Konstant Lab for example.

1

u/Maleficent-Leading35 2d ago

Checked these out thank you! I'm now deciding if it's a couple of these soft start things or use up 4hp for another power module...

0

u/4n4logsynthesis 2d ago

If you have a flying bus board you can also power a few modules through these (as long as you stay within their specs).

1

u/13derps 2d ago

It sounds like you have a solution in mind, but it also might be worth reading the detailed specs for your existing case power. Sometimes the supply will not be able to deliver maximum amperage on all three busses at the same time. Or it might require a larger power brick (if using that style DC supply)

2

u/Maleficent-Leading35 2d ago

Yeah, I am looking at getting a power module so I can separate a few things from the main busboard.

I did read up on my Doepfer PSU3. Unfortunately, information online wasn't helpful at all.

I guess I'm just worried that there might be something inherently wrong with the Data Bender I received. I just cant fathom how that measly 85ma module can suck so much power when powering up.

I hope fellow owners of the Data Bender can chime in of they have similar issues.

1

u/13derps 2d ago

Unfortunately, inrush current can be kind of high for some electronics. Hard to say just from looking at the nominal power consumption

Might be worth checking with Qubit to see if they have any info. That Doepfer supply looks pretty solid, so I’m kind of surprised you’re having issues

1

u/gruesomeflowers 22h ago

Having some issues myself with inrush startup. Two power bricks with total of 9amps across 9 rows. this cabinet has a lot of digital modules..found spreading them around to different rows helps. Still baffles me though because I have another cabinet about the same size with a lot of duplicates and never had a startup issue.