Scope of this technical record
Use this hub when an SJ300 / L300P case needs to route no-display, E09, E01-E04 or E07 into the correct input, output, braking or replacement path.
SJ300 / L300P drives contain hazardous DC-link voltage and braking energy. Isolate, lock out and verify discharge before internal access or braking-resistor work.
Hitachi SJ300 / L300P E09 and no-display route
The route connects readable E09 trips and dark-keypad failures through the same energy and control-power evidence chain.
Use trip timing to choose the first route
The SJ300 / L300P family is old enough that many requests start with 'replace the board' or 'find a used drive'. The service route should start with the event. E09 and no-display cases ask whether the drive has input energy, DC-link charge and auxiliary control power. E01-E04 cases ask when output current became excessive. E07 cases ask why the DC link rose above threshold.
The same physical drive can require three different first checks: input/precharge/control supply, motor/cable/output current or regeneration/braking/DC-bus sensing. Keeping those routes separate prevents an old but repairable drive from being condemned too early.
Repair or replace decisions need original-cause evidence
Used-board replacement is common on legacy Hitachi drives, but a donor board should not be the first conclusion. A no-display case with a shorted downstream control load, an E01 case caused by a jammed machine, or an E07 case caused by unmatched braking duty can damage a replacement part or leave the fault unchanged.
The hub therefore links every major fault chain to circuit paths and evidence records. The decision is not just whether a board is available; it is whether the field condition that produced the original fault has been proven and corrected.
Hitachi first-route selector
| Observed condition | First evidence route | Parts decision boundary |
|---|---|---|
| No display | Input, precharge, DC link, auxiliary supply and keypad/display route | Control board after supply proof |
| E09 | Line voltage, precharge, DC bus and control circuit energy | Used board after voltage route proof |
| E01-E04 | Operating state, motor/cable, load, current detection and gate drive | Output module after field route proof |
| E07 | High line, regeneration, deceleration, braking resistor/BDU and bus sensing | Control board after braking proof |
Field record checklist
- Full type code and voltage class
- Exact fault and status/timing
- Input voltage and DC-link evidence
- Motor/cable/load condition
- Brake resistor or BDU evidence
- Board labels and repair history
Technical basis and reference documents
This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.
Lists SJ300 fault codes, trip status context and the E01-E09 diagnostic basis.
Supports E07 regeneration and overvoltage interpretation for the L300P family.
Supports braking resistor, braking unit and duty-cycle evidence for E07 cases.
Model records
SJ300-5.5KW DB1 through DB4 drawing-family record for control-supply, current-feedback and output-stage evidence. It is not universal compatibility proof.
SJ300-7.5KW DB1 through DB4 record supporting E01-E04, E07, E09, no-display and repair/refurbishment decisions for matched 7.5 kW frames.
Decision page for choosing repair, used board, refurbished drive or replacement when a legacy SJ300/L300P asset has a costly fault.
Fault records
The SJ300 / L300P trips E07 when the internal DC bus exceeds the overvoltage threshold. The trip may appear during deceleration, stop commands, descending or overhauling loads, high incoming AC voltage, or braking resistor / braking unit duty problems.
The SJ300 / L300P trips E01 at constant speed, E02 during deceleration, E03 during acceleration, or E04 under another operating condition such as DC braking, current-transformer error or noise-induced current detection.
The SJ300 / L300P trips E09 at power-up, during a load step, after a line dip, during contactor operation, or together with keypad reset / blank display behaviour.
The SJ300 / L300P has no keypad display, intermittent resets, no readable trip history, a dead front panel after a power event, or a used keypad / motherboard replacement that does not restore operation.
Drive trips during constant speed, deceleration, acceleration or other running state.
Drive trips after sustained load, incorrect motor data or cooling trouble.
Trip often during deceleration or regenerative load conditions.
Low-bus trip or unstable operation under input/load disturbance.
Blank keypad, intermittent reset or no fault code available.
Board and assembly records
Collects field and bench evidence that separates high-line voltage, regeneration, ramp and resistor-duty problems from DC-bus sensing, brake-chopper and control-board repair boundaries.
Collects field and bench evidence that separates motor/cable/load overcurrent from current-transformer feedback, noise, gate-driver and output-stage failures before repair, used board or replacement decisions.
Collects field evidence that separates upstream input, precharge/DC-link, auxiliary supply, keypad/display interface and control-board loading before repair or replacement decisions.
Supports current-feedback, output-stage, control-supply and repair-risk routing.
Supports 7.5 kW output-stage, bus-voltage and control-supply repair/refurbishment decisions.
Circuit and diagnostic records
Routes E07 overvoltage cases through machine energy, stop timing, ramp profile, descending or overhauling loads and DC-bus rise before the brake unit or sensing path is blamed.
Maps the braking-unit and resistor evidence needed when E07 follows deceleration: built-in BRD or external braking unit, resistor value, thermal switch, wiring, duty cycle and stop conditions before repair.
Defines the repair boundary after line, load and braking evidence are closed: DC-link measurement, bus feedback divider or sensing route, control board interpretation and conditions where a used board or replacement drive becomes the better decision.
Routes E01-E04 timing through motor/cable/load proof, output terminal evidence, current transformer or current feedback plausibility, noise/harness evidence and the boundary where the drive-side output stage becomes suspect.
Maps the drive-side boundary for persistent E01-E04 faults after motor/cable/load proof: gate-drive command, isolated driver supply, protection feedback, output bridge static evidence and repeat-failure prevention.
Keeps E01-E04 troubleshooting outside the drive until motor wiring, cable condition, terminal box contamination, brake release, shaft freedom and load inertia have been proven.
Routes E09 and related reset behaviour through upstream line condition, fuses, contactor, precharge, DC-link charge/storage and bus sensing before board-level repair decisions.
Separates dark display, intermittent reset and no-code cases into input energy, auxiliary supply startup, low-voltage rails, keypad connection and control-board load evidence.
Connects the E09 undervoltage route to the no-display route so a technician can decide whether the problem is upstream supply, precharge/DC link, auxiliary power or downstream board loading.
Connects E01-E04 timing to load isolation, CT/current feedback evidence and output-stage suspicion.
Routes E07/E09 through supply, regeneration, braking, charge and sensing decisions.
No display requires low-voltage control supply and keypad/interface evidence because no code may be available.
Output-stage suspicion comes after motor/cable/load and current-feedback evidence are separated.
E07 appears during deceleration, stop, lowering/overhauling motion or high-inertia load operation, often after a ramp change, resistor installation or repeated reset attempt.
E07 remains after ramp and resistor evidence is reviewed, or the DC-bus / brake behaviour does not match the machine event timing.
SJ300 or L300P reports E01, E02, E03 or E04 overcurrent, with the trip tied to constant speed, deceleration, acceleration or another operating condition.
E01-E04 persists after the motor/cable/load route is proven, or the drive has repeated overcurrent after a power-board / output-module repair.
E09 undervoltage, dark keypad, intermittent display reset, no readable trip history, or an old SJ300/L300P that fails after input disturbance or fuse/contactor work.
E01-E04 overcurrent trip with operating-condition evidence.
Legacy SJ300 repair, used motherboard or replacement-drive decision.
Turn this record into a qualified service request
A repair decision is much more reliable when the request includes the exact identity of the drive, the first fault evidence and the machine condition when the symptom appeared.
- Complete drive type code / MLFB or nameplate model
- Fault code, fault value and first event before reset
- When the event appears: power-up, enable, ramp, run, decel or stop
- Motor/cable connected or isolated during the symptom
- Visible board, option-card, module and connector identifiers
- Previous repair history, replacement parts and repeat-failure pattern