From Repairs

ET312B Repair Service for EU Customers

An ET312B Repair Service for EU Customers is now available from! offers EU ET312B Repair Service

You can find our more about their service by visiting the Blackstore ET312B Service page.

And our Spare Parts section now contains the most common replacement parts for all modern ErosTek Power Units, including:



ET-312 Firmware Upgrade 1.6

This is an archival post from our original site, placed here for posterity. This is NOT a new update for the current ET-312B. 

This page contains the latest maintenance firmware update from ErosTek for a select number of ET-312s sold in May through July 2004. In order to use this upgrade, you must have an ErosLink serial cable, a Windows PC or virtual machine, access to the HyperTerminal program (under Start > Programs > Communications) and be able to follow the directions contained in the Upgrade Instructions file.For OS X users, please follow the instructions sent regarding use of the shareware application ZTerm.

This upgrade will ONLY work with units having a copyright of ’03 and firmware version 1.5 and is designed to cure the “Failure 77” errors that some users have experienced.

Your ET-312 should show the following screens during startup in order to use this upgrade:

(c) ’03 ErosTek
• • • • • • • • • • •

ErosTek ET-312B
SelfTest OK V1.5

Note: the copyright (c) must show ’03 and version = V1.5

This upgrade does not add any additional features or functionality to the ET-312B.


  1. Download the instructions (.pdf)
  2. Download the upgrade file (.upg)
  3. Print out and follow the instructions

Repair Parts for ET312B

While you may never have a problem with your ErosTek ET312B, after a many years of use, some things may wear out. Like the output level pots. Or the battery. If it’s within warranty, let us know. Here’s a list of the most common repair parts and their sources:

Rechargeable Battery Module
Part: ET312B-BATT available from ErosTek
– Includes mounting bracket and instructions.

Output Potentiometers (Level A and B)
Part: RP302 available from ErosTek
– Replace if output levels become erratic or unreliable.

Battery Charging IC (U13#)
Part: LM2941CT available from DigiKey
– Replace whenever battery fails to charge.
– Connecting the wrong AC adapter is a normal cause of failure of this IC.
– Observe ESD precautions for handling static-sensitive components.

Output Transistors (Q3, Q4)
Part: IRF9Z24N available from DigiKey
– Replace both to resolve “Failure 20” errors.
– Observe ESD precautions for handling static-sensitive components.

Tact Switches (Up / Down / Menu / OK switches)
Part: TL1100CF160Q available from DigiKey
– These switches are rated for 100,000 presses but not if liquids get inside 🙂
– Replace as needed

For the more parts, visit our Spare Parts section.

Got a problem?

I’m not sure how to connect my ET-312 to my computer?

I have questions about how to use the ErosLink software?

Solutions to Other Common Problems

I lost the remote control to my remote unit. How do I get a new one?

  • Solution: SexTek normally stocks extra remotes.

I lost the AC Adapter for my unit. How do I get a new one?

  • Solution: SexTek can normally supply AC Adapters. Do not use any other adapter without checking with SexTek first. You may cause serious damage to your unit.

My  ET-312B (or ET232)  works great while connected to my portable CD player but how do I listen to the music at the same time?

  • Solution: Some portable CD players have a “line” output as well as a headphone jack. Simply connect your ErosTek unit to the line output and use your headphones as usual. If your player only has a headphone jack, you can get a “Y” cable locally to allow you to plug both the headphones and your ErosTek unit at the same time. You can use the same trick with your computer’s sound output.

How do I connect your product to a home stereo system?

  • Solution: The best way is to use the “Tape Out” or “Tape Record” jacks. You will need a (widely available) cable with RCA plugs on one end and a 3.5mm plug on the other.

I tried connecting my CD player to the audio input and it doesn’t do anything.

  • Solution: The cable should be plugged into the headphone or line output of your CD player.  Try turning the Multi Adjust control all the way up.  Try increasing the volume on your CD player.  Some CD players have a volume limiting feature that should be turned off.  Finally, some CD’s (especially classical ones) have an extremely wide dynamic range. It is normal for the quieter passages on these recordings to not cause any stimulation. Most people find pop or dance music works best.

The output of my unit is erratic or unsteady.

  • Solution: This is likely due to a bad cable or connection. With use, the cables do wear out and can develop an intermittent connection–especially at the banana plugs.  Try a different cable and/or accessory and see if the problem goes away.

With most electrodes, my unit has power to spare, but I can sometimes turn it all the way up with one particular electrode.  Is that normal?

  • Solution: A few different things might be happening. First, most electrodes must be damp or wet when using them. Ideally, you should use a conductive gel designed for e-stim (TENS) use. Dry electrodes will not work properly. Second, if you’re using our new ET-312, make sure the Set Pwr Level? menu option is set to the Normal or High level.  Finally, certain electrodes made of conductive rubber materials have a high internal resistance. This makes the sensations less intense with these electrodes regardless of what type of e-stim unit they’re connected to. It’s a limitation of the electrode design.

If you don’t see an answer to your problem above, please check our Frequently-Asked Questions or Repair category for additional information and assistance. You can also reach our Customer Support department too.