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IZ2 Tech Notes

IZ2 Critical Failure

TN0983

Product: IZ2, IZ2H, LZ48
Version: All
Date Added: 2016-12-05

Issue

We discovered a failure mode in the IZ2 electrical stimulator / LZ48 battery pack that can lead to improper device output. Although the failure occurrence is relatively rare, this failure mode can result in the unintended delivery of high current to the research subject and thereby potentially cause injury or death. As such, we are taking every step possible to address the issue and ensure the best possible safety for your research subjects.

We strongly recommend that you verify proper device operation prior to connecting any research subjects and initiating any stimulation protocols. If an LZ48 battery is fully discharged while still connected to the IZ2, under some operating conditions electrical components in the IZ2 stimulator can be damaged. After the failure of these electrical components, higher than intended stimulation current can be delivered to the research subject during subsequent device operation. In this condition, IZ2 devices must be returned to TDT for repair or replacement of the damaged components.

Solution

  1. To minimize risk, never allow the LZ48 battery to fully discharge. When the battery charge indicator is getting low, stop the experiment, disconnect the subject, and recharge before further use.

  2. Always verify proper operation of your device before connecting to a research subject. If you observe red LED status lights on your IZ2 during setup, do not connect a research subject or proceed with the experiment. Please see the IZ2 Operation Guide for additional details. If you encounter any problems or need help verifying proper device operation, please contact TDT Technical Support for assistance.

  3. Contact TDT for a free LZ48PC protection cable. This new cable will monitor line voltages and protect the IZ2 from electrical component damage even if the battery is inadvertently allowed to fully discharge. The cable will replace the LZ48 to IZ2 cable that shipped with your device and can be easily installed in a matter of seconds.

  4. Consider upgrading your current LZ48 battery to a newer LZ48M battery pack that includes several additional protections and safety features including medical grade isolation from mains power when charging.

LED synchronized ringing or noise on IZ2

TN0927

Product: IZ2
Version: All
Date Added: 2013-09-05

Issue

When using the IZ2 stimulator in an electrically shielded environment (such as a Faraday cage) you might see LED synchronized ringing and/or a thicker noise floor when operating in Voltage mode. These symptoms are caused by radio frequency interference that is concentrated by the shielding, coupled with the equipment chassis and ultimately runs down the lines causing the interference to be picked up in recordings.

Solution

Adding ferrite beads to the LZ48 battery cable and LZ48 ground cable chokes the RF signal out of the lines, substantially suppressing the amplitude of the LED- synchronized pulse and lessening the RMS of the noise floor. Place the RF chokes towards the LZ48 side of the cables. Also, insulating the bottom of the LZ48 from any metal surface is highly recommended. Contact TDT for a cable kit.

Building a custom headstage to use with PZ, IZ, or ACO

TN0896

Product: PZ5, PZ2, PZ3, IZ2, IZ2H, IZ2M, IZ2MH, ACO32, ACO64
Version: All
Date Added: 2012-02-08

Issue

This tech note provides the information needed to wire a custom or third-party headstage to TDT amplifiers, stimulus isolators, and commutators.

Solution

The PZ5, PZ2, PZ3, IZ2, IZ2H, IZ2M, IZ2MH, ACO32, and ACO64 all use the same female mini-DB26 connectors. The mating male connector is made by TE Connectivity (previously Tyco), part number 5749621-2, and can be purchased from Newark, Digikey, or similar vendors. The part number for the connector's backshell kit is 749608-2.

The PZ5, PZ2, PZ3, IZ2, and IZ2H are all battery powered. To conserve power, each bank of channels will not turn on unless a headstage is connected. The device detects whether a headstage is connected through the HSD (HeadStage Detect) pins: pins 18 and 19. These pins should be shorted together on the headstage connector. If pins 18 and 19 are not shorted the headstage will not be detected and the bank that it is connected to will power off.

Important

This does not apply to the IZ2M and IZ2MH. In those devices all banks are always powered.

The pins on the headstage should be made to match the connector on the intended device. The pinouts for each device are shown below.

Note

The user must increment the channel numbers by 16 (or 8) according to the amp, mode and position of the connector. So, for the connector labeled 'A', A1 is channel 1 while on the connector labeled 'B', A1 may be channel 17.

PZ5 Connector Pinout for Building Headstages

PZ5 NeuroDigitizers have up to eight 26-pin headstage connectors on the back of the unit. The connectors are labeled alphabetically from bottom to top. Each connector carries signal for one bank of channels with ground and reference. The corresponding channel numbers depend on:

  1. the reference mode configurations

  2. the position of the bank in a logical amplifier.

For simplicity sake, the diagrams below assume channels for that connector begin with channel 1. For example, A1 - A16 represent the 16 channels coming from the connected headstage.

Local Mode

None Mode

Shared Mode

Differential Mode

PZ2 Connector Pinout for Building Headstages

PZ3 Connector Pinout for Building Headstages

IZ2, IZ2M, IZ2MH Connector Pinout for Building Headstages

IZ2H Connector Pinout for Building Headstages

The ACO passes signals from each header to the pins on the associated DB26 connector on the face of the commutator. The unused pins should not be connected. The pins on the headstage should be made to map to the connected amplifier/stimulator via the header as follows:

ACO Headers - Pinout for Building Active Headstages

For PZ2 or PZ5

For PZ3

ACO Headers - Pinout for Building Passive Headstages

For IZ2, IZ2M, or IZ2MH

For IZ2H

Leakage current on output of IZ2 in Current mode.

TN0894

Product: IZ2, IZ2H
Version: IZ2 SN < 3000, IZ2H SN < 2000
Date Added: 2011-12-06

Issue

In current mode, there may be a leakage current on the output of the stimulator. This DC offset depends on the temperature.

This issue has been addressed in new IZ2s. A fan has been added to the unit for better cooling and resistor changes in the output stage reduce the effectiveness of the offset error. An ACC16-Z coupler is also available to eliminate the offset.

Solution

If you experience this problem, contact Support to request an RMA for return and upgrade.

IZ2 Output Drops Unexpectedly

TN0890

Product: IZ2, IZ2H, RZ
Version: TDT Drivers < 72
Date Added: 2011-07-15

Issue

In voltage mode, the output of the IZ2 can go to zero for approximately 300-350 milliseconds and then return to the originally intended output. In current mode, a similar drop will appear to occur on the monitor ADC, but the output does not actually drop.

Solution

This error is caused by the IZ2 DSP Card installed in the controlling RZ device. If you experience this problem, contact TDT Support to request an RMA for return and repair of your RZDSP-I card.