Scope of this technical record
Series-level routing page for technicians handling legacy LG / LS Starvert iS5 drives, particularly units with control-power, IGBT and CPU-board damage.
The iS5 contains hazardous line and DC-link voltages. Diagnosis of internal power electronics and supply regulation is restricted to qualified personnel after isolation and verified discharge.
Why the Starvert iS5 family matters now
The Starvert iS5 family remains commercially relevant because installed equipment can outlive official product availability. For the SV185iS5-4N0, current market evidence identifies an 18.5 kW / 25 HP, 380–460 V class drive that is discontinued by the manufacturer while still offered in repair and replacement channels. A failure therefore does not lead to a simple retail replacement decision: users may need repair, a verified used unit, board recovery or a retrofit assessment.
Most English-facing supply pages establish only that the drive exists or can be repaired. The differentiating technical need is a failure path that protects replacement electronics: an iS5 with an IGBT failure and damaged CPU board may contain an auxiliary-power fault capable of destroying another CPU board as soon as it is fitted.
iS5 technical-commercial map
| Evidence | Meaning for technician | Meaning for owner |
|---|---|---|
| SV185iS5-4N0 identified in 400 V family | Correct model route before board work | Repair/replacement search can be specific |
| Product shown as discontinued | Exact new replacement may be constrained | Repair and verified exchange become valuable |
| Documented 24 V overvoltage case | Supply must be proven before CPU board substitution | Avoid repeated board loss and downtime |
The family route in this database
The iS5 series page is organized around the way failures arrive in practice. A user may have only a full model number, an IGBT explosion, an apparently dead control board, an unstable auxiliary rail or a history of repeat repair failure. The route connects that evidence to the control-power board, feedback circuit and two constrained workflows rather than turning every symptom into a generic fault-code page.
Official family literature contributes equipment identity, basic wiring and fault-history context. The documented repair case contributes the rare board-level evidence: the 24 V supply rose as high as approximately 56 V, multiple rails rose and fluctuated together, and the root cause was found in the feedback path around a 431-type reference and a physically fractured R50 resistor.
Why control power is a high-value entry point
A missing 24 V supply stops a controller; an uncontrolled 24 V supply can destroy it. This distinction is critical for legacy-drive repair. When an IGBT event and CPU-board failure occur together, it is unsafe to assume the CPU board is an isolated casualty or that fitting another board completes the repair. The documented iS5 case shows a repaired unit destroying a second CPU board because regulation had not been secured.
The corresponding database objects are therefore not merely “power supply” articles. They map a chain: switching supply → secondary rail sampling → feedback reference → stable CPU supply → safe control-board testing. This chain can support future inquiries for board repair, compatibility checking and controlled recovery of discontinued drives.
Published entry points
The initial iS5 cluster focuses on one exact high-value model and one strongly evidenced failure cascade. It intentionally avoids claiming full board coverage across every iS5 frame. A visitor with SV185iS5-4N0 evidence can enter the model record, the 24 V overvoltage case, the repeat CPU-board damage page or the feedback regulation circuit page.
Expansion should follow either confirmed source material or real search and inquiry signals: additional iS5 frame boards, fault-history entries, power-terminal configurations and donor-board compatibility may be added only when evidence is sufficient.
Field record checklist
- Capture full model and board evidence
- Verify control-supply rails before replacement testing
- Record previous destructive failure history
Technical basis and reference documents
This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.
Family, model, wiring and fault-history context for Starvert iS5.
Documents the 24 V rail rising to approximately 56 V, ZD13/R50 feedback diagnosis and restored stable outputs.
Confirms model-market identity, rating context and discontinued-product supply signal.
Model records
Fault records
A repaired LG / LS SV185iS5-4N0 shows abnormal or unstable low-voltage supplies; the nominal 24 V control rail may rise far above normal and endanger connected control electronics.
An iS5 drive initially presents with power-stage and CPU-board damage; after apparent repair and test power-up, the CPU board fails again.
Low-voltage outputs fluctuate or rise together, creating misleading control-board, keypad or hardware-fault symptoms before the drive can be evaluated normally.
Circuit and diagnostic records
A reconstructed functional path for the SV185iS5-4N0 case: switching transformer outputs feed control rails while an optical feedback/reference network, including the ZD13/R50 branch, regulates the secondary supply level.
Maps the documented cascade in which initial IGBT and CPU damage was followed by a second CPU-board loss because the low-voltage supply had not yet been proven safe.
SV185iS5-4N0 has suffered IGBT/CPU damage or presents unstable low-voltage rails; the 24 V control supply is suspected of rising above its intended level.
An iS5 drive has destroyed a CPU/control board after IGBT repair or a donor CPU board is being considered for testing.