28 Oct 2015

Protek 608 RS-232 cable teardown

Protek 608 RS-232 cable
This post is a continuation of the Protek 608 DMM software project.

Here’s some photos of the Protek 608 RS-232 cable teardown:

Bill of materials

You know a teardown is serious when a BOM is produced! 😛 This may be overkill, but I have plans in future to develop my own transceiver hardware that instead of using RS-232 to connect to a PC, it will use a cheap WiFi module or Bluetooth module.

C1, C2
Capacitor, Tantalum
33 µF, 6.3V, polarosed

R1, R2
Resistor (0805)
1 kΩ

R3, R4
Resistor (0805)
100 kΩ

Resitor (0805)
22 kΩ

Resitor (0805)
4.7 MΩ

Diode, Switching (SOT-23)

D2, D6
Diode, Switching (SOT-23)

D3, D4
Diode, Switching (SOT-23)

Transistor, NPN
2N3904 (SOT-23)

Transistor, PNP
2N3906 (SOT-23)

Transistor, PNP
2N3906 (SOT-23)

Header, 5-pin, 2.0mm, Right Angle
-  Molex 89401-0510
-  Sullins SWR201-NRTN-S05-RL-WH

LED on back??
SMD 14.. (2927)??

Photo-receiver ??

About the Author:

Hardware and software engineer with experience in product development and building automation. Director at Cabot Technologies and Product Manager at NEX Data Management Systems.


  1. […] A teardown of the Protek 608 RS-232 serial cable […]

  2. Jack Martin

    Very Good brake down
    can you call me ay (918) 629-9297 I was the director of electronic at ORU University
    we use the protek 608 to Demonstrate to the students i have a ? i think you can answer

  3. SlickClick

    I suspect that its 2 IR sensors; one TX one RX…
    I dont have a Cable for this Model (I have the 506 & 608); these Protek Meters are some of the Best Multi-meters ever made, IMHO…
    Because you have the Cord & Original Breakout board; you likely could rig its Serial Wires to Wifi or Bluetooth unit…
    Theres a YouTube video from SerialIO.com w/ the 506 using a Serial to Bluetooth Adapter (BlueSnapAAA)…
    If you broke that unit (BlueSnap) down; and hardwired it to the 608 Breakout Board and 3d Printed a new rear housing to mate to the Original Dongle head that fits the Meter; youd have a Nice sleek Bluetooth Adapter…

    Because I dont have a cable I have to think of how to create one; maybe using an Arduino kit of some sorts…

    • There’s an IR LED (transmit) and IR LDR/sensor (receive).

      I agree that the Protek 608 is an awesome meter, one of my favs for sure. I recently picked up a Brymen 869S which is now my #1 🙂

      Making a Bluetooth or WiFi adapter for the Protek would be an interesting project.
      I actually wrote a Java library a while back that decodes all serial comms, it’s on GitHub: https://github.com/dariancabot/Protek608
      Porting that across to C or Arduino C++ wouldn’t be too difficult as the decoding was really the hard part.

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