IndustrialDriveDataDrive Board & Diagnostic Database
Functional board area

Generic VFD Auxiliary SMPS Board Area

Generates logic, relay, fan and local electronics supplies from the drive DC bus or auxiliary input.

Board-area evidence record7 min read

Scope of this technical record

Functional SMPS board area used in no-display, weak display, rail collapse and control-power repair requests.

Safety boundary

Board-area observation must occur after isolation and DC-link discharge verification. CMOS and control boards are static-sensitive.

Auxiliary SMPS board evidence route

1Startup feed
→
2Controller
→
3Transformer
→
4Feedback
→
5Loads

Photos should show the supply as a system, not just a burned component.

Auxiliary SMPS board evidence image

VFD auxiliary SMPS board evidence route startup controller feedback rails loads
The image shows which supply areas a repair request should document.

What to document on the SMPS area

The most useful photos show the startup feed, switch/controller area, transformer, optocoupler feedback, secondary rectifiers and electrolytic capacitors. A single close-up of a burned component is less useful than a board-level photo with connector and rail context.

Board evidence table

Use this table to decide whether the no-display case is a regulator, feedback or load-isolation problem.

SMPS board evidence

AreaWhat it suggestsNeeded evidence
Startup resistor/feedNo initial oscillationInput and feed path photo
Primary switch/controllerSupply failureVisible damage and part location
Optocoupler feedbackPulsing/unstable railsFeedback area photo
Secondary electrolyticsWeak boot/rippleAge, bulging, leakage, heat marks
Downstream loadsRail collapseFan/I/O/driver branch evidence

Field record checklist

  • Full board photo
  • SMPS close-up
  • Rail behavior
  • Connected loads
  • Contamination/storage history
  • Keypad/fan/relay symptoms

Technical basis and reference documents

This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.

VFD auxiliary SMPS and control-power pathIndustrialDriveData

Circuit path for this board area.

Linked circuit records

Circuit
VFD auxiliary SMPS and control-power path

Maps the auxiliary supply route that powers the CPU, keypad, I/O, relay logic, fan control and often isolated driver supplies.

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Evidence intake

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
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