Troubleshooting Guide, by Franco A. Conte
The main goal of troubleshooting is to identify and resolve issues within a system by eliminating parts that are functioning correctly and precisely isolating the cause of the error.
How do we perform troubleshooting at Neuroelectrics?
First, it’s crucial to understand how information flows through the system, from the generation of signals to the reception of data:
Physical Phenomenon: Electrical signals under the skull.
Interface 1: Gel.
Subsystem 1: Electrodes.
Interface 2: Electrode cables connection.
Subsystem 2: Electrode cables.
Interface 3: Necbox connector.
Subsystem 3: Necbox.
Interface 4-A: Wifi.
Interface 4-B: USB Isolator.
Subsystem 4: PC.
Subsystem 5: NIC (Neuroelectrics Interface Controller).
Interface 5-A: LSL (Lab Streaming Layer).
Interface 5-B: TCP/IP.
Subsystem 6: Third-party software (Viewer, Marker Sender, Matlab, E-Prime, BrainVision Analyzer, etc.).
When a problem occurs, the error can be in any of these interfaces or subsystems. The goal of troubleshooting is to identify which of these components is causing the issue.
Example: "Flat-Lined" Channel in EEG (Matlab)
Let’s imagine that one of the channels shows a flat signal (“Flat-Lined”) in the EEG when viewed in Matlab. Below are the steps to resolve the issue.
Step 1: Initial Evaluation
Is the Matlab subsystem misconfigured?
If other channels show a signal, it is unlikely that Matlab is misconfigured.Is the interface between Matlab and other components functioning correctly?
If the other channels are showing signals, we can assume the interface is working fine.Is the NIC subsystem sending and receiving signals correctly?
If all channels are having the same issue, the problem might be with the NIC.Is the PC managing the information correctly?
If the error occurs only in one channel, it is unlikely the PC is the issue.Is the Wi-Fi or USB connection stable?
If only one channel has an issue, the connection is probably not the cause.Is the Necbox functioning properly?
If we’ve ruled out all other subsystems, we can assume the Necbox is functioning correctly, although further time may be needed to evaluate it if we don’t find the fault in other components.
Step 2: Practical Checks
If we haven’t identified the issue after the initial evaluation, we follow this process of elimination by checking each component systematically:
Necbox Connector: Check if the pin corresponding to the faulty channel is damaged or bent. This is one of the first simple checks we can perform.
Electrode Cables: Ensure that the electrode cables are in good condition and properly connected. If the cable is damaged, replace it.
Electrode Position: Check if the electrode is positioned correctly. If not, adjust it to the proper location.
Electrode Condition: Inspect the electrode to verify if it’s damaged. If it is, replace it with a new one.
Gel/Saline Solution: Check if there is enough gel or saline solution on the electrode. If it's missing, the signal may not be clear.
Step 3: Advanced Diagnosis
If the issue persists after the initial checks, we can swap components to pinpoint the origin of the fault. This is especially useful if the client has multiple complete systems available.
Swap Connectors: Swap the connector from the faulty channel with one from a functioning channel. If the problem persists in the same channel, the issue may lie with the cable or connector.
Swap Cables: If swapping the connector doesn’t resolve the issue, try swapping the cable connecting the Necbox to the electrodes.
Necbox Inspection: If the error persists, there may be internal damage to the Necbox circuitry. This is a more complex case that might require more time to diagnose and resolve.
Alternative Method: Swapping Subsystems
In some cases, especially if the client has several systems, we can swap entire subsystems to test each one in isolation. This can speed up the diagnosis by quickly narrowing down which component is faulty.
