FAQ/Shorted coax cable and the L13 inductor
A short across the coax cable sends a power surge through the L13 inductor on the DAQ and destroys it. The three DAQ LEDs still look normal, but the data crossing the coax is corrupted and the connection fails every time. The damage is cumulative: one bad cable will kill every DAQ it is plugged into, and at least one lab lost several before realising. Another had a cable that shorted only when bent into a particular position. Test the cable: with the coax disconnected from everything, put a multimeter in continuity mode and touch the outer and inner conductors — or the SMA body and the centre pin. It should read open circuit; a beep means a short. Shorts are usually at one of the ends near the connectors, or along the length if the cable has been damaged. Trim back and redo the connector, or discard the cable. Repair the DAQ: replace the L13 inductor on every affected board — Digikey CBC3225T101MR. Two independent labs confirmed this recovers the boards. Occasionally it is not recoverable: if the short drew enough current to damage other components or the PCB, replacing L13 twice still failed in one case. Desoldering tip: 390 °C is enough even for lead-free solder. If it will not melt, the iron tip is oxidised — add fresh solder to the tip first, then touch the inductor.
More help on this wiki
- Coax cable characterization — Measured performance by cable and length, and the supply voltage each needs.
- Guide/How to test and debug your Miniscope V4 — Where cable testing sits in the wider debugging order.
- Data Acquisition Box — DAQ hardware overview, schematics and PCB repository.
Still stuck? Bring it to the drop-in office hours, browse the full FAQ library, or see Guide/Common pitfalls and FAQs.
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Original Google Group threads
These are threads on the external Miniscope Google Group, not pages on this wiki. They are where this answer came from and are kept for attribution and context. For anything new, please use the wiki forum above instead.
| Google Group thread | Activity | Answered by |
|---|---|---|
| Retrieve frame error even after firmware update | 2021-05-19 → 2022-11-04 | Daniel Aharoni, Clara Hartmann |
| How to remove L13 inductor. | 2020-10-07 | Daniel Aharoni |
| Miniscope V4 getting hot, error with frame retrieval and LED not turning on | 2021-02-15 → 2023-02-15 | Daniel Aharoni, Federico Sangiuliano |