Scope of this technical record
Board-reference interpretation of the reviewed BALDOR 15H auxiliary-power schematic for safe diagnostic routing and replacement protection.
This is a functional drawing reference, not a published spare-board match. Do not order or substitute components or assemblies without matching the installed drive and board revision.
What is actually visible in the drawing
The one-sheet schematic is labelled BALDOR 15H and depicts multiple auxiliary-power regions. Visible control components include UCC3802 and UCC3804 switching-supply controllers, TL431 reference devices and CNY17-4 optocouplers. It also displays switching and rectifying elements, transformer/secondary regions and labelled low-voltage outputs including +21 V, +29 V, +15 V and -15 V.
That is sufficient to publish a functional power-supply reference: a technician can identify which conceptual regions must be proven stable before a connected logic assembly is trusted. It is not sufficient to claim that a specific production power board, frame or catalogue number is represented without physical board matching.
Why this board reference is commercially relevant
The official manual directs an HW Power Supply case toward internal connection checks and logic power board replacement. In a legacy-drive repair context, a customer can spend money on a replacement or repair only to find that the underlying supply remains unstable. A reviewed power-supply mapping creates a practical safeguard against that sequence.
This page therefore answers a narrower but higher-value question than a manual download: before replacing expensive electronics, what evidence should be established around the internal supply source and its derived rails? Repair firms can use such evidence for better triage; end users can use it to prepare a more credible request.
Visible sub-circuit groups
| Drawing evidence | Functional role | Diagnostic relevance |
|---|---|---|
| UCC3802 / UCC3804 | Controlled supply stages | Conversion/control investigation |
| TL431 / CNY17-4 | Isolated regulation feedback | Rail stability and feedback reasoning |
| +21 V / +29 V | Derived auxiliary rails | Source for downstream regulation/loading |
| 7815 / 7915, ±15 V | Bipolar control supply | Analog/control stability evidence |
Safe use in a repair workflow
Use this page after the drive identity and symptom are recorded. An HW Power Supply case may justify review of this drawing first; a ground-fault case should remain on its output-isolation route unless it also presents clear control-supply evidence. A bus trip should not be forced into this page unless rail or control symptoms are independently observed.
During a qualified bench assessment, document stable or unstable supply behavior at the functional level: upstream conversion, feedback regulation and downstream rail loading. The objective is not to publish hazardous probe instructions, but to tell the decision maker why a logic board or whole-drive replacement is or is not protected from repeat damage.
Limitations and next data required
The next improvement would be an installed board photograph, visible board number or a matching service source for a specific Series 15H model. Such evidence would permit compatibility mapping and potentially a more exact assembly record. Until it exists, IndustrialDriveData deliberately identifies this asset as a reviewed drawing reference.
This limitation does not make the record weak; it makes it useful and honest. The page exposes a valuable internal functional relationship while avoiding false precision.
Field record checklist
- Drive/model identity match
- Board/revision label evidence
- Fault linked to supply symptoms
- Connection and visual inspection evidence
- Controlled verification before replacement
Technical basis and reference documents
This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.
Official source for Series 15H operating scope, fault terminology and first-line troubleshooting guidance.
Reviewed schematic identifying UCC3802/UCC3804, TL431/CNY17-4 feedback and derived low-voltage rails; original source drawing is not redistributed.
Public repair-service evidence supporting continuing maintenance demand for the obsolete/legacy family.
Linked circuit records
A reviewed supply drawing identifies two controlled conversion regions using UCC3802 and UCC3804, supplying isolated low-voltage functions used by drive electronics.
The drawing shows TL431 reference and CNY17-4 optocoupler feedback elements in both controlled supply regions, creating a diagnostic boundary between output-rail error and switching-stage response.
The reviewed drawing exposes +21 V and +29 V secondary regions feeding a visible 7815 / 7915 bipolar regulator section and +15 V / -15 V outputs.