repairing VU LEDs on PreSonus Central Station

Motivation:

I ordered a PreSonus Central-station stereo input/output selector for my main office (where I do most of my editing/mixing away from “the studio”)
It’s nice to be able to switch between various inputs (computer, synth, etc) and varoius outputs to check sounds,  including 3 speakers (Equators, crappy Logitechs) and 2 separate headphone outs.

I found a great deal on a used one on eBay:

0 - seller listing copy.png
(user)Name of original seller removed…

 

Screen Shot 2015-03-12 at 9.24.06 AM.png
As you can see from the close-up, the unit was listed and sold in fine working condition, with no damage to the front panel.

Bought the unit, and as soon as it showed up, I knew there was trouble.

The box was oversized, and I could FEEL the unit sliding around in ample empty space inside. Opening the box revealed just how little care was taken to pack and pad this unit for shipping.

1 - opening box copy.jpg
First opening the box, you can see the PreSonus wrapped in a token amount of bubble rap, having moved around enough to rip up the box.

 

 

 

 

4 - box damage.jpg
the Box showed up looking like it’d lost a fight.

 

Taking the unit out of the box, all the surface-mount hardware (pots, buttons jacks) seemed ok, except the central VU-meters. Their plastic lenses were rattling around inside.

5 - meter damage copy.jpg

 

Plugged the unit in, and it seemed to pass and handle signal just fine. Literally the only problem was the fall-out of the 6 - meter lights copy.jpgtwo lens-grids of plastic that focus surface-mount LEDs from PCBs inside to the front-panel VU sttrips…

 

Recon..

After emailing the seller, we agreed to a partial refund of the value it would cost to repair. Since I planned to attempt to repair it myself, I did the honest thing and got an inspection and repair-estimate from a colleague. After the partial-refund was filed, honored, and positive feedback exchanged, it’s…

 

 

TO THE BENCH !

Process:

IMG_20150313_131045524_HDR.jpg
carefully took the knobs off the front pot-stems; the front-face is coming off from the rest of the body, so it’s a tight fit between the circuitry that mounts the interface (knobs/buttons/etc) from rest of the unit that handles power and audio.
IMG_20150313_131003497_HDR.jpg
all the front-panel UI is on a separate daughter-board PCB that’s flush up against the front. The  standoff of 4 black wires goes from the front-end PCB daughter-board to the LED (grand)daughter board.

 

IMG_20150313_130740082_HDR copy.jpg
the VUs are on another separate (grand)daughter board with a between the LED strips and the holes where we see these. Note how there is a standoff connecting the UI dauhgter to the LED granddaughter.
IMG_20150313_111944085 copy.jpg
these combed plastic pieces act like a row of lenses, where each LED  on the circuit board gets focused into its own slot flush with the front panel. I simply moved the (grand)Daughter PCB, re-glued the plastic combs, and re-assembled.

 

IMG_20150313_130321554_HDR copy.jpg
The fix boiled down to using glue (Gorilla, gel) to secure the LED lense-combs into the slots. Very little room for error, so held them flush while the glue set. The trickiest part was making sure the LEDs PCB properly slide into its spot with proper alignment of the molex stand-off interconnect. BE GENTLE with stuff like this.
IMG_20150313_131110005_HDR.jpg

Once the glue dried, it was just a reversal to put the unit back together. Some excess glue ran through the holes, but it STUCK now.

IMG_20150313_132348634 copy.jpg
a (mostly) re-assmbled unit works and looks fine.

Conclusions:

As a seller, please make sure to package all audio equipment with ample padding, and no wiggle room.

As an buyer, many times when audio gear “breaks” in transit, it breaks at an (obvious) weak spot, that may be easier (and more satisfying) to repair yourself than to go through hassle of returning and re-purchasing. The more “surgery” I do on gear, the more I realizes how much stuff is (mostly) well-built on the (cheap) circuit board (where it counts), with often superficial and low-tech weaknesses in the housing (where it’s easiest to reduce manufacturing costs).

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