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RX6 Tech Notes

Front Panel A/D converters on the RX6 exhibit an unusually large DC offset

TN0861

Product: RX6
Version: All
Date Added: 2009-08-13

Issue

The front panel A/D converters on the RX6 might exhibit an unusually large DC offset when first powered up.

Workaround

After powering up the RX6, open zBUSmon and click Reboot System. This will remove the large DC offset.

Distortion is seen on RX6 DAC outputs when signals with amplitude greater than 10V are played out

TN0233

Product: RX6
Version: Microcode version 62 and below
Date Added: 2007-01-07

Issue

If a signal with amplitude greater than 10V is sent to a DAC on an RX6 with microcode 62 and below, the output will be distorted. More distortion is seen in signals with greater amplitudes.

Solution

Update to latest version of TDT Drivers. After installing the drivers, reprogram the RX6 with the new microcode. After reprogramming, all signals greater than 10V presented to the DACs will be clipped to 10V.

Noisy ABR recordings using an RX6 and BioSigRP

TN0202

Product: RX6
Version: All
Date Added: 2005-11-22

Issue

When ABRs that are recorded using the RX6 to present the stimulus appear noisy, the problem might be due to the stimulus sample rate.

Workaround

The RX6 allows users to select from a wider range of sample rates than other TDT processors. However, when using BioSigRP to record on the Medusa preamplifier, it is necessary to set the stimulus sample rate to an even multiple of the 25kHz sample rate used on the preamplifier. If the stimulus sample rate is not an even multiple of the recording sample rate, then jitter in the triggering between the two modules will cause the averaged recordings to appear noisy. If a stimulus sample rate is required that is not an even multiple of the 25kHz on the recording unit, then an external trigger must be used to trigger the stimulus and recording devices.

Anomalous signal on an analog output of an RX device when the channel is not in use

TN0198

Product: RX5, RX6, RX7, RX8
Version: All
Date Added: 2005-10-06

Issue

The DAC outputs of the RXn processors will continue to generate a signal under the following conditions:

  • Input to the DAC channel is greater than zero immediately before switching the DacOut channel parameter.

  • Input to the DAC channel is greater than zero immediately before halting the processing chain.

  • Input to the DAC channel is greater than zero immediately before loading a new processing chain.

Workaround

Make sure that the inputs to all DAC channels are zero before doing any of the above. This can be done by gating the signal or setting the DAC output to zero before switching channels, halting the processing chain, or loading a new chain.

Note

The anomalous signal can be terminated by cycling power on the zBus rack holding the RXn processor.

Intermittent hum heard through speakers or headphones when using a USB2.0 interface

TN0195

Product: RX6, UZ2, UB2
Version: All
Date Added: 2005-09-22

Issue

An intermittent low frequency hum may be heard through headphones or speakers when the output device is being housed in a ZB1 caddie using a USB2.0 interface. The frequency is variable, and the hum may be constantly present or come and go over time. This has been reported with the RX6 but might occur when using other RP/RX devices with the USB2.0 interface. This problem is only found with USB interfaces and disappears when using the gigabit interface.

Workaround

Upgrade to the Gigabit interface.

Using non TDT amplifiers

TN0140

Product: RA16BA, RX5, RX6, RX7, RZ2, RZ5
Version: All
Date Added: 2004-09-23

Issue

TDT modules that connect to amplifiers are compatible with any amplifier (including those not sold by TDT). Any TDT module with analog or fiber optic inputs can acquire signals of ± 10 V.