Back in October I purchased a standalone Z-2300 subwoofer on eBay, knowing I could build a DIY remote control pod based on my working Z-2300 set. I disassembled my original remote and deciphered the pinout in a matter of hours. A board was sent off to BatchPCB the next day; two weeks later, I posted this video on YouTube:
Since then, I’ve received dozens of messages from fellow Z-2300 owners, all asking for more information.
Here’s the deal: It would be unethical of me to release the schematic and/or circuit board for public usage, and quite possibly a breach of Logitech’s intellectual property. There are no copyright, trademark, or patent markings on the Z-2300 speaker set or the control pod’s circuit board. However, a Logitech Product Team member at the Logitech message board writes:
“The wiring diagram is not a public document.“
This is understandable—no company publicly releases schematics for their products, and definitely does not allow for others to profit from the company’s products/services. As an engineer, I wholeheartedly respect that.
What is bothersome is Logitech’s backwards policy on replacement parts. I’ve owned my Z-2300 set since late 2005. The volume control has always exhibited terrible channel balance at low volumes. This is caused by differences in the left and right potentiometer gangs, which are pronounced at the lower and upper thresholds of rotation. Such tolerance errors are common amongst dual-ganged pots. There are two fixes: 1) Replace the potentiometer and hope for less error, or 2) Implement attenuation circuitry at the audio input (series resistors), such that the maximum counter-clockwise position of the potentiometer is avoided. I could’ve fixed this imbalance myself. Instead, it was easier to raise the volume on the pod and decrease volume at the PC. Anyway, I called Logitech’s support line one day to see about the prospect of purchasing a replacement remote control. After explaining the annoyance, I was kindly told that Logitech could send me a completely new Z-2300 set for free. Not even a shipping charge. What?! I was willing to shell out cash for a replacement part, and here they were offering to send me a $200 speaker set on their bill.
It turns out this is how Logitech’s warranty works. Rather than repair a faulty device or send out (or sell) replacement parts, they prefer to give away brand new products. I can see how the cost of labor for repairs could be less than profitable, but surely it would be cheaper to send out small replacement parts rather than entire product sets. The Z-2300’s remote control cannot be worth more than $10 in parts—probably much less considering they’re mass produced. Although fantastic for customer service, this approach to repairs is incredibly wasteful. Logitech is a fantastic company, and I was appreciative of their offer, but I declined. I did not need or want a second Z-2300 set (at the time). I was just nitpicking…
Logitech’s wasteful policy affects products besides their Z-2300. A few eBay sellers offer hand-made audio interface cables for the Z-5500, which bypass its digital remote control. These $5-$10 contraptions sell for ridiculous prices ($45-$80). Considering that there are no replacement parts to be sold, this is a clear case of demand outweighing supply. So, the question is, why on Earth doesn’t Logitech sell replacement parts? It would be profitable!
With all of that said, I would very much like to release the information I have unearthed. From the messages I’ve received, it is clear that plenty of people with out-of-warranty Z-2300’s are interested in purchasing Logitech replacement parts. Several people have lost their control pods during moves; some have dropped or otherwise broken them; some want to tap into the circuitry for unique modifications (often multiple subwoofers…); some, like me, just wanted a better performing volume control.
Since I cannot publicly release my replacement Z-2300 control pod PCB, or even the schematic or pinout, below are pictures taken during the disassembly of the pod:
The PCB silkscreen provides wiring labels for all 9 wires (plus 1 shield “wire”). Of course, you’d have to open the pod up yourself and use a continuity checker to find out which pins of the High Density 15-pin D-Sub connector these wires go to. Lastly, I can verify Logitech’s claim that standard VGA extension cables should not be used with Z-2300’s. The center row of pins for a VGA extension cable are all tied to ground. Logitech uses a single pin in this row for an audio signal. Anyone attempting to extend the interface cable should make sure to use a pin wired 1:1 (that is, pin 1 is wired to pin 1, pin to goes to pin 2, etc., and no pins are tied together).
EDIT (April 27, 2010) – SCHEMATIC RELEASED!
DISCLAIMER: This design is for personal use only. Information is provided without warranty, either expressed or implied. Schematic and information below may contain intellectual property of Logitech.
Someone by the name of “HxCxK” independently uncovered and released a rendition of the Z-2300 schematic last month. Since he has let the cat out of the bag, below is what I originally found:
Miscellaneous schematic notes:
- Resistor R108 omitted (serves to buffer supply rail into standby pin; not critical)
- Potentiometers not measured (10k parts are common and work well in this circuit)
- Capacitors C100, C101 are optional. Someone with more free time may wish to investigate the frequency response with and without these parts.
Principles of Operation:
- A stereo audio signal comes in through the green 3.5mm connector.
- Signal passes through the remote’s main volume potentiometer for attenuation.
- Signal is then fed down to the subwoofer enclosure for pre-amplification.
- The pre-amplifier(s) distribute the audio into two places:
a) To the left and right satellite amplifier (and subsequently to the 2 speakers)
b) Back up to the remote.
- Inside the remote, the signal is split again:
a) To the headphone jack
b) To the subwoofer potentiometer (where it is combined to mono at this point)
- Output from the subwoofer potentiometer finally gets fed back into the enclosure and last, into the subwoofer amplifier.
D-15 Connector Pinout:
|Subwoofer Line Input
|Standby, Active Low
|Right Line Input
|Right Headphone Output
|Left Line Input
|Left Headphone Output
|15V Supply Rail
See images above for connector numbering. Those who wish to quickly test their Z-2300 can ignore most of this. The Z-2300 switches on when Pin 5 is connected to Pin 15. Then, apply audio signals as follows:
Pin 12: Left Input
Pin 6: Right Input
Pin 1: Subwoofer Input
Pin 3: Audio Ground
Printed Circuit Board:
The board can be purchased from BatchPCB in unassembled form. This is entirely non-profit. As such, NO SUPPORT IS PROVIDED. You are on your own.
|Alps RK0971221Z0 (10k, Volume)
|Alps RK09712200MC (10k, 15mm)
|0.01uF Multilayer Ceramic Capacitor
|Male to Female, HD, 15-pin D-Sub