Troubleshooting Guide

COMPUTER DOES NOT SEE MOBILE I/O

If you attach Mobile I/O to your computer, and the computer is unable to communicate with the Mobile I/O hardware there are five basic possibilities for the source of the problem:

  1. The Mobile I/O is not powered up
  2. The Software is not installed properly
  3. The FireWire bus did not reset correctly
  4. The FireWire cable is bad
  5. The FireWire hardware has been damaged

MOBILE I/O IS NOT POWERED UP

The first thing to check is that the Mobile I/O is, in fact, powered up.

If Mobile I/O is powered up and booted properly, the Power, Sample Rate, and Locked front panel indicators will be illuminated. If these indicators are not illuminated, the Mobile I/O is not powered properly or the unit’s firmware has been corrupted. If you determine that you are powering Mobile I/O properly and the indicators are not illuminated, you will need to contact Metric Halo support.

If you are bus powering the Mobile I/O, there is a possibility that you have overloaded the power rating of the power source. Please see the troubleshooting section “Not enough power on the Bus” for details on troubleshooting this problem.

If the Mobile I/O is properly powered, then check the next possibility.

SOFTWARE IS NOT INSTALLED PROPERLY

In order for the computer to properly communicate with the Mobile I/O, the various components of the driver software need to be installed correctly. If the software is not installed correctly, the communication between the computer and Mobile I/O will fail in various ways. If the MobileIODriver.kext is not properly installed in the /System/Library/Extensions folder of your computer, you will not be able to use the Mobile I/O for audio and you will not be able to control the sample rate or clock source of the Mobile I/O with the computer.

THE FIREWIRE BUS DID NOT RESET CORRECTLY

When a device is plugged into the FireWire bus, a FireWire bus reset occurs automatically. The bus reset interrupts bus activity and reconfigures the bus so that all devices on the bus become aware of all the other devices on the bus. Sometimes the reset does not complete successfully, and the bus becomes partially hung. In this case, the “FireWire” indicator on the front panel of the Mobile I/O will not be illuminated. When the “FireWire” indicator on the front panel is not illuminated, the Mobile I/O cannot transport audio over the FireWire bus.

Generally, this condition can be fixed by disconnecting the Mobile I/O from the bus and reconnecting it.

If the disconnect/reconnect cycle does not fix the problem, another device on the bus may be interfering with the proper operation of the bus. If you have other devices on the bus, try disconnecting them from the bus and only using the Mobile I/O.

If removing other devices from the bus solves the problem, it is likely that there is a problem with either one of the devices you removed or with one of the cables connecting the devices. You’ll need to isolate the problem component.

If removing the other devices from the bus does not fix the problem, check the next possibility.

THE FIREWIRE CABLE IS BAD

Metric Halo provides two high-quality overspec’ed FireWire cables for use with Mobile I/O and we recommend you use them. For various reasons you may decide to use other cables than the ones provided by Metric Halo. Under ideal circumstances all FireWire cables will provide years of service. However, cables will and do go bad. Cable failures can be difficult to track down. If you are experiencing problems with connecting or bus powering Mobile I/O you should try swapping the cable with another known-good cable.

If the FireWire cable is not the source of the problem, check the next possibility.

THE FIREWIRE HARDWARE HAS BEEN DAMAGED

If all else fails, it may be that the FireWire hardware on either the Mobile I/O or the computer has been damaged. While this is an exceptionally rare occurrence, it is a possibility. The FireWire hardware can be damaged in the following ways:

  1. If you insert a FireWire cable into a port upside down, it will damage the FireWire port and/or the connector. It is difficult to insert the connector upside down, but it is possible to force it. Never force a FireWire connector!
  2. It requires significant pressure, but it is possible to force a FireWire connector over a male XLR connector pin. If you do this, the connector will be shorted and it will destroy the port on the other end. Again, never force a FireWire connector.
  3. Some devices that are bus-powerable and conform to the IEEE1394 standard will return power to the remote FireWire port if a power ground fault occurs. If the remote port is protected against this situation, nothing will happen. If the device does not use bus power, nothing will happen. But, if the device is fully compliant, uses bus power, and the remote device is not protected and supplies a high enough voltage on the bus, the remote device port will self-destruct.

If the FireWire hardware on the computer has been damaged, it will not communicate with any FireWire devices. Be sure that you are not checking this case with a bad cable, as a bad cable can make it seem like the FireWire hardware has failed since it will consistently keep devices from connecting properly to the computer. If the computer is damaged, you will need to contact the manufacturer for a repair or, as a stopgap measure, you can use a third-party FireWire adapter card. Metric Halo also recommends the use of a third party FireWire hub between the computer and any FireWire devices. Any potential issues will damage the hub, not the computer, saving time and money in the long run.

If the FireWire hardware on the Mobile I/O has been damaged the MIO will not communicate with any other devices. In this case, please contact Metric Halo support for help in getting your Mobile I/O hardware repaired.

GROUND LOOPS

Audio systems, in general, are susceptible to ground loop problems. Digital Audio Interfaces for computers are even more susceptible to grounding issues since they must interface with the computer’s system ground, which tends to be much more dirty than the ground used by audio gear. By taking care when you connect the various components of your audio system you can avoid the hums, buzzes, and noises that characterize ground loops and other grounding problems.

First of all, most grounding issues go away if you utilize balanced interconnects between your audio gear. Balanced interconnects inherently reject ground differentials and common mode interference introduced by grounding problems. Balanced connections are not much more expensive than unbalanced connections and solve so many problems that if both ends of the connection support balanced interconnect, you should not even consider using unbalanced cables.

You may get the idea that we hate unbalanced connections. You’re right. We do. You should too.

If you have to use unbalanced connections, or if any ground-related problems remain, you will find that the key to the issue is ensuring that you have a common hard ground between all the gear that you are interfacing. This is commonly referred to as a technical ground. A technical ground is characterized by a consistent low impedance path between each device and a common reference ground, ideally connected directly to earth ground. The above is sometimes difficult due to electrical wiring problems in the house, studio, or stage you are using. In the extreme case, you may need to hire a qualified electrician to untangle and correct electrical service problems in your working environment.

Unbalanced connections are a fact of life when interfacing with guitar amps, and, paradoxically, guitar amps are extremely sensitive to grounding issues since they use so much gain to achieve the effect of a “Guitar Amp”. If you will be interfacing with guitars and guitar amps, you need to be very careful about grounding.

Common electrical wiring approaches to residential installations, and sub-par studio and stage installations use daisy-chained grounds for ease of installation and economy. Unfortunately, daisy-chained grounds can introduce signficant ground differentials between sockets, and these differentials can vary depending on other loads (like refrigerators, TV’s and other household appliances) on the circuit.

Other problems with electrical service installations are improper wiring of power phases to the three-phase service and improper connections between the safety ground and hot legs of the three-phase service. These types of problems tend to be characterized by loud 60Hz hums in the audio system. Unfortunately, these types of problems extend well beyond noise in your audio system to genuine safety hazards. If you determine that your electrical wiring has problems beyond a simple daisy-chained ground, you should consult a licensed electrician immediately, as ignoring these problems can damage either you or your gear.

If you do not have a well implemented technical ground, you will want to ensure that all of the devices in your audio system are plugged into the same phase and same ground. You can generally accomplish this by running all your gear off of the same socket (using a power strip or power conditioner) if your gear uses less power than is supplied by a single circuit from your premises’ wiring (generally 10-15 amps in residential installations and 20 amps in commercial installations).

It is usually a bad idea to put some devices in your system on a power conditioner and other devices on a separate strip, socket or conditioner, unless you have a technical ground. The power conditioner can introduce a ground differential.

The power supply provided with Mac laptops does not have a hard ground. This means that if the laptop is plugged in, it will dump high frequency buzz into the ground. That ground is shared with the Mobile I/O Firewire cable. If Mobile I/O will be connected unbalanced to other audio gear, the ground buzz can contaminate the signal if the Mobile I/O is not hard-grounded to the same ground as your other audio gear. To hard ground the Mobile I/O you will need to use a 3-pin power cable on the Mobile I/O power supply and power the Mobile I/O with the power supply. Plug the 3-pin IEC power cable into the same circuit and same ground as your other gear.

On the other hand, if you are encountering ground loop problems while operating with the Mobile I/O’s power supply, you may find that lifting the Mobile I/O’s ground resolves the problem. This can be accomplished by using a 2-Pin IEC cable (without the third ground pin), or by using a ground lift block (generally available in hardware stores, also known as a 3 pin to 2 pin converter). In general, it is better to resolve the fundamental grounding problems in your system, but this is a quick fix that may help. There are no hard and fast rules for solving this type of problem other than fixing the fundamental grounding issues, so if you go this route, you will have to experiment with lifting various grounds in your system until you find the magic combination. Or switch to balanced interconnects.

Finally, the Apple Cinema Display has a known issue with its backlight dimmer. If you run the Apple Cinema Display with its backlight at anything other than full brightness, the backlight dimmer will introduce a midrange buzz into the system ground which will appear in unbalanced interconnects (input and output) with Mobile I/O. This issue affects other devices that connect to the computer’s system ground. The work around is to run the display at full brightness, or use balanced interconnects.

FIRMWARE UPDATE PROBLEMS

Details on updating the firmware of Mobile I/O are available here.

It is possible for firmware updates to “not take”. This appears to be related to DSP loading issues in the Mobile I/O, other devices on the FireWire bus, and the state of the FireWire system software on the Mac. If you have problems with updating the firmware, try the following procedure:

  1. Remove all devices from the FireWire bus
  2. If your Mobile I/O is using external power, disconnect the power
  3. Reboot your computer
  4. Attach the external power supply to the Mobile I/O while holding down the front panel Mute button; this will boot the Mobile I/O into the safety boot firmware
  5. Connect the Mobile I/O to your computer
  6. Run the firmware updater

Since Mobile I/O implements safe-boot and safe firmware update, you should always be able to use this procedure to update the firmware, even if something goes horribly wrong (like losing power during an update).

BUS POWERING MOBILE I/O

If you are bus powering the Mobile I/O, there is a possibility that you have overloaded the power rating of the power source.

NOT ENOUGH POWER ON THE BUS

While all Macintosh computers with built-in FireWire supply bus power, some models do not provide enough power on the bus to power Mobile I/O. If this is the case, you will generally find that the Mobile I/O will boot on initial connection, but will then lose power or will reboot repeatedly after a short period of operation.

Newer Intel Macs have implemented an in-rush current limit circuit breaker that may trigger when powering a Mobile I/O unit. This will prevent the computer from booting the unit, but not from powering it. So you can use an external supply or battery to get the unit powered up and then use the computer’s bus power to provide power to the Mobile I/O.

Some Mac models provide enough power if they are plugged into the wall, but will not provide enough power while running on batteries. If the computer does not provide enough power, you will need to use an external power source with Mobile I/O.

The external power supply provided with Mobile I/O is the perfect solution if you are using Mobile I/O in an environment where ac power is available. The external power supply will actually provide power to the bus and can be user to power other bus-powered peripherals (see other bus powered devices).

If AC power is not available, you will need to use an external battery-based power source to power Mobile I/O. Any source that provides 9V-30V and can support 12-15W of power consumption will work well with Mobile I/O. Check with Metric Halo for specific recommendations.

When using an external battery source, DO power Mobile I/O directly from the battery – not through an inverter. DON’T power the computer with an external battery and use the computer to power Mobile I/O; doing so will not resolve your bus power problems, and it will give you more limited run times. If you need to use the external battery with the computer use two batteries or split the DC supply at the battery and power both the Mobile I/O and the computer.

OTHER BUS POWERED DEVICES

Mobile I/O consumes enough power that it is very unlikely that you will be able to successfully bus power Mobile I/O and any other bus-powered device (except for a hub) from the same computer. If you plan on using other bus-powerable devices with your computer, you will need to either self- power your other devices or self-power the Mobile I/O. It is probably best to use the Mobile I/O’s power supply in this situation since Mobile I/O will then provide approximately 30 Watts of power to the bus (roughly 3x what most Portable Mac’s will supply). This will allow you to power all the rest of your devices without any concern of running out of power.

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