DIY Logitech 4000 SC1 mod (Serial Port)

This is an update to my previously-built Logitech 4000 SC1 modification in 2011. Note that the modification was originally designed to work with Parallel ports. Since such ports are now obsolete, changes to the circuitry have been implemented to allow the modified camera to be connected to newer laptops via USB ports (by using a USB-to-Serial Port adapter).

It is strongly recommended that you read the article about the previous version of this camera (link provided above) along with the comments left by the readers as this will give you a brief background as to why this update is necessary. A lot of details in this page will not make sense to you if you are not familiar with the history of the project.

WARNING: I assume no responsibility for any damage caused to your camera/equipment by following the information presented here. Keep in mind that success cannot be guaranteed even if you have followed the instructions exactly as described. This modification must be attempted only with those who are comfortable working with electric circuits. Proceed with caution and follow instructions at your own risk.

DIY Guide Camera (Logitech 4000 SC 1 modification) (2)
Modified Logitech 4000 SC1 (using Serial port interface)


DIY Guide Camera (Logitech 4000 SC 1 modification) (14)
This photo shows how the components are connected together. The box shows the components that will be placed together in a project box/case.
Click here to view a larger image. This diagram shows how the components are connected together. I have placed actual photos on Martin Burri’s diagram (used with permission) to help visualize the connections. Note that in this modification, the Parallel port is replaced by a Serial port. The rest of the circuit remains the same. To see how the previous version of this camera was wired and inspect the difference between the two circuit diagrams, click here.
DIY Guide Camera (Logitech 4000 SC 1 modification) (11)
Internal components about to be placed inside the housing. Note that an optional USB hub was used to minimize the wires leading to and from the housing.


DIY Guide Camera (Logitech 4000 SC 1 modification) (9)
A photo showing the main board of the camera, the 4066 IC, and the wire that connects them to the Serial port (an adapter) and the USB port of the laptop.


DIY Guide Camera (Logitech 4000 SC 1 modification) (10)
Here’s a closer look at the optional USB hub. Note that the wires have been soldered directly onto the board to save weight and minimize space. The brand of the USB hub is CD-R King.


DIY Guide Camera (Logitech 4000 SC 1 modification) (13)
Another view showing how the components are connected together.


DIY Guide Camera (Logitech 4000 SC 1 modification) (7)-labels
Here’s a closer look at the USB-to-Serial port adapter along with the BC547 transistor, 330 ohm resistor, and the IN4148 diode. The 9-pin male port was removed and the connections were soldered directly on to the board to minimize weight and save space.
DIY Guide Camera (Logitech 4000 SC 1 modification) (12)
Here’s the project box (with holes drilled at the appropriate places), the webcam-to-telescope adapter, and two mounting screws to hold the adapter in place.


DIY Guide Camera (Logitech 4000 SC 1 modification) (6)
Components about to be placed inside the casing (Left to right: USB hub, 4066 IC, Logitech 4000, Serial port adapter)


DIY Guide Camera (Logitech 4000 SC 1 modification) (5)
Just enough space to accommodate the components. Note that only one wire leads out of the camera: the wire that connects the laptop to the USB Hub (thus, without the optional hub, two wires will lead out of the camera).


DIY Guide Camera (Logitech 4000 SC 1 modification) (4)
Front view of the camera. The two screws hold the webcam adapter securely onto the casing.


DIY Guide Camera (Logitech 4000 SC 1 modification) (3)
Three optional LEDs were installed on the side of the housing. The green LED connects to the built-in LED of the USB hub. The yellow LED connects to the built-in LED of the webcam. The red LED connects to the GND and Pin 7 of the Serial port (using an appropriate resistor) to allow monitoring of the state of PIN 7 (which sends the long exposure pulse).


DIY Guide Camera (Logitech 4000 SC 1 modification) (3)
Install the appropriate drivers. Here’s a link to the Logitech Quick cam Pro drivers download site.


Guide Camera Modification Logitech 4000 (12)
Install the autoguiding program of your choice. I am using PHD2 Guiding. Select the appropriate camera from its menu.


Guide Camera Modification Logitech 4000 (10)
Select guide camera. Choose “Long Exposure Serial Webcam” to tell PHD Guiding how to appropriately handle the camera.


DIY Guide Camera (Logitech 4000 SC 1 modification) (1)
Select the port into which the guiding signals will be sent. If you are not sure, simply play around with the ports and use trial-and-error. Also, check the appropriate boxes.


Autoguider November 2015
Test your camera! Shown here is an initial test conducted in November 2015. I have yet to guide a deep-sky capture using this modified “serial port” SC1 camera. It may have to wait for a while though, as I am currently unable to visit a dark-sky site for some DSO imaging.

Related link:
Logitech 4000 SC1 Modification (Parallel Port)
Home-built Autoguider Project

For featured photos, click here.
For tutorials on how to get started with astrophotography, click here.
For DIY astronomy projects useful for astrophotography, click here.
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© Anthony Urbano (Manila, Philippines)

13 thoughts on “DIY Logitech 4000 SC1 mod (Serial Port)

  1. Hi Eteny, Thank you for getting around to writing it up. This is perfect.
    I like the idea of one cable out of the box!
    I am still waiting for stuff from ebay :-)

    • Greetings to you all! I just happened upon this site and saw the Logitech QC mod and figured, I’d give it a try,,, I found a seller on Ebay that has these Webcams at about $4.00 US + $6.00 S&H. I bought 10! I soon realized how horrible my vision was and I desperately need glasses! I’ve nearly completed the first and have 2 more underway after breaking 2 others, but was able to repair one. The only thing left to do with the first is to box it up . I was astonished to see how well the QC 4000 reveals the darkness with this mod, but be warned… If you are not a patient person with a reasonably steady hand this mod might not be for you. Definitely use a thin soldering tip with about a 30-60 watt iron set right in the middle of the dial, and a #11 Exacto blade when scoring the PCB and cutting the leg of the Sony IC. Bit by bit I scraped away the solder on the Sony IC leg contact, then gently bent it upwards after heating it up just a little. I previously broke away 2 of these pins from the IC but was able to repair one drizzling solder to the contact point coming out of the IC from a sewing needle. Take your time and DO NOT RUSH or be impatient! Many thanks to you Mr. Eteny for a fine tutorial and an excellent learning experience! I’ll also be visiting the local eye doctor soon!

  2. Hello! I do not quite understand the update. Please enlighten me on the connections from the camera to the computer…. and other connections…. I need some explanation on their connections

    • Hi Abdul,
      This diagram here summarizes everything. The other illustrations are simply used to elaborate. Which part of this diagram are you having problems with?

      • ok… so… We have ABCD connected to 4066IC which is connected to the serial port adapter which connects to the computer from the now autoguider by using USB 2. But then how about the original USB 2 wire that came connected to the camera prior to the modification?

        Will that too have to be connected to the computer?

      • The USB cable that came with the camera must be connected to a USB port. There are two sets of signals controlling the modified camera. One is being sent through the USB cable that came with so it must be connected to a USB port (to a USB splitter in this case), and another signal being sent via the USB-to-serial adapter, which reaches the camera through the 4066IC and eventually, points A, B, C and D.

        To save weight and space, and to make it more compact, I simply soldered the wires connecting the camera and the USB splitter. The ‘port’ was removed, and the wires were soldered to make the proper connections.

        You will then have an extra USB cable (the one that came with the camera) that you can opt to swap with ‘the USB cable that connects a laptop and a USB splitter’ to give it a longer cable :)

  3. Hi!
    ok.. now for the software part… the quickcam driver…: Does the default cd driver for the quickcam suppose to run on windows xp? Or could it run even on say windows 8…?


    Step 3, the drivers for most recent operating systems, I could not find anything… So I tried finding the driver for the camera but it runs on xp windows. Will it matter?


    Forgive me for the questions. Already have the same model in my crosshairs… trying to learn from you…

    • Just head to the Logitech website and download the appropriate drivers. Logitech 4000 is only supported in XP (or older) and Vista. For Win 7 (my current OS), I have found out that you can still use the same driver for Vista, but you will have to install the driver manually (tell Windows to search for the driver in a specified folder). Considering that the camera was introduced in 2002 (almost 15 years already!), I am actually quite surprised it still works with newer OSs.

  4. I have modified the webcam. I have a problem when using PHD2. the images are lost at times. The program Guidemaster works well.
    (BC547) —— (470 ohms) —– (1N4148) — (rs232)

    from Argentina.

  5. Hello i have purchased a SAC7 imaging camera. if im not mistaken the cam itself should be the Logitech 4000, only thing is that it comes with a 25 pin serial port, would this modification work with this cam?

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