Data Recovery Case File · Diagnostics · Reading the USB Tree

The bridge answered, the drive drew nothing: forensic reading of a System Information listing — and the update acquitted along the way

Most enquiries describe symptoms; this one attached evidence. Her Seagate 1TB hybrid drive — pulled from a broken MacBook Pro, accessed since by SATA cable — "didn't work anymore" after she upgraded to macOS Mojave. She'd run the eliminations properly: different USB slots, different computers, an independently powered caddy. And then the gold: she pasted her iMac's System Information USB readout for the connected caddy — the bridge chip's full introduction, vendor and product IDs, speeds — including one line that, read correctly, contained the entire diagnosis: "Current Required (mA): 0." This page reads that listing the way the bench does, acquits the suspect her timeline had charged, and finishes with the drive's contents where they belong.

Forensics of a listing — and the acquittal of Mojave

Here's what her paste actually shows, line by meaningful line. The entry exists at all: so the caddy's bridge chip — the interface controller whose vendor and product IDs fill the listing — enumerated successfully; the USB conversation between iMac and caddy is healthy, which single-handedly acquits her cables, ports, and both computers. "Current Available: 900mA": the Mac offering full power to whatever's connected. And then the tell: "Current Required: 0mA." A working storage device negotiates its appetite — a caddy with a live, spinning drive behind it requests real current and reports it here — so a bridge introducing itself while requiring nothing is a front door answering for an empty house: the drive behind the bridge never came up, never drew, never joined the conversation. The fault localises decisively past the bridge, into the drive itself — precisely where her powered-caddy test had already pointed. Which leaves her prime suspect standing in the dock: the Mojave upgrade, charged by timing. Acquitted, on the evidence — operating systems talk to drives through exactly the doorway her listing shows healthy, and an upgrade neither reaches nor rewrites a drive's internal ability to start; the hybrid, several years into service and recently living the rough-and-ready caddy life, failed of its own mechanics on a week that happened to contain an update. Correlation charged it. The 0mA convicted someone else.

The recovery

At the bench the empty house got its locksmith: the hybrid's mechanism was no longer completing its start-up — the fault class her listing predicted — and was brought to serviceable life with the donor and firmware attention its condition required, then imaged in full on the PC-3000 through the USB Stabilizer: the whole terabyte, patient passes, coverage in the high ninety-nines. (Her hybrid's flash cache, for the record and per this archive's standing note on SSHDs: an accelerator, not the archive — her data proper lived on the platters, and came off them.) The volume from her old MacBook's life mounted whole from the image — verified by opening files across it, delivered on new media — and the report closed with the acquittal in writing, because a customer who supplies evidence deserves a verdict that cites it.

Outcome

Full recovery, and a diagnostic technique promoted to public knowledge: the USB tree is testimony, and anyone can read it. On a Mac, System Information's USB section (System Report → USB); on Windows, Device Manager's equivalent — find the entry for your enclosure or caddy and ask its two questions. Is the bridge listed at all? (Absent: the fault may be cable, port, or a drive dragging the bridge down — a neighbouring case in this batch decodes that darker version.) Listed but with no storage volume and a power draw at or near zero? The drive behind it never stood up, and no amount of cable-swapping, port-hopping or OS-blaming will change what the number already said. She did the eliminations, captured the evidence, and sent both. The bench's first job was simply agreeing with her paste — and the trade runs faster every time a customer arrives holding the transcript.

Our case files are drawn from genuine enquiries received by our laboratory over the past ten years, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery procedure our engineers apply to that fault, using the equipment listed.