Marantz 2500 User Manual

TOROIDAL TRANSFORMER
For MARANTZ models 2500/2600
Eng. Antonio Pelli Neto
Marantz 2600 and Sansui G9000 (from my collection)
Service manuals for Marantz receivers are famous for their lack of information, or providing information that is
incorrect and/or incomplete. In the specific case of Marantz models 2500 and 2600, the manuals additionally
contain misleading information about the capacity and positioning of some electrolytic capacitors, and they do not
contain important data on voltage and current for the toroidal transformers accompanying the products. These
transformers were also famous for burning out, which presented problems in the construction of new units.
The purpose of this text is to allow electronic technicians, or even Marantz 2500/2600 owners with dead toroidal
transformers, to recover your receivers. Although my training is in Civil and Mechanical engineering, my hobby is
recovery and restoration of electronic equipment, especially equipment considered "vintage". I do not work as an
electronic technician, nor do I provide maintenance services for electronic equipment. This, as I’ve said, is just a
hobby, although I've been involved in it for over 40 years. So, I take no responsibility for the information provided
here, however I have successfully utilized it in the recovery of my own devices.
A POSSIBLE ERROR DETECTED IN SERVICE MANUAL
The Marantz 2500 and 2600 service manuals display the following diagram for connecting the toroidal
transformer:

Marantz 2500 Specifications

General

Frequency Response	20Hz to 20kHz
Total Harmonic Distortion	0.1%
Damping Factor	60
Weight	62 lbs
Tuning Range	FM, MW
Channel Separation	50dB (1kHz)
Output	250 watts per channel
Weight (lbs)	62 lbs

Summary

Marantz 2500/2600 Toroidal Transformer Problems and Analysis

Service Manual Deficiencies and Transformer Burnouts

Details common issues with Marantz 2500/2600 service manuals, including incomplete data and transformer failures.

Author's Hobby and Disclaimer for Restoration

Explains the author's hobby of vintage electronics restoration and includes a disclaimer of responsibility for the information provided.

Potential Error in Service Manual Diagram

Highlights a specific error detected in the service manual's diagram for connecting the toroidal transformer.

Detailed Analysis of Marantz 2500/2600 Transformer Wiring

P800 Board and Transformer Connection Points

Examines the P800 board and the transformer's connection points, referencing schematics and photos.

Comparison of Expected vs. Actual Wire Color Sequences

Compares the service manual's expected wire color sequence with the actual colors found on the units.

Identification of Center Tap (CT) Wire

Identifies the yellow wire as the Center Tap (CT) based on circuit analysis and power connector information.

Marantz 2600 and 2500 Toroid Specifications

Marantz 2600 Toroid Specifications and Wiring

Provides detailed specifications for the Marantz 2600 toroidal transformer, including wire colors, voltages, and current.

Marantz 2500 Toroid Specifications and Wiring

Details the toroidal transformer specifications for the Marantz 2500, focusing on amplifier output voltage differences.

Toroidal Transformer Replacement and Reassembly

Choosing Between Rewinding and New Transformer Construction

Discusses the pros and cons of rewinding the original toroidal transformer versus building a new one.

Installation of the New Toroid Transformer

Illustrates the mounting of the new toroidal transformer and its initial wiring connections.

Reassembly of Power Module and Final Connections

Covers the reassembly of the power module, transformer base, and final electrical connections.

Testing and Verification of the Repaired Unit

Pre-Power On Checks and Critical Moment

Describes the final checks before powering on the unit and the critical moment of testing the repair.

Successful Operation and Tuning Adjustments

Confirms successful operation, including tuning the FM radio and making final adjustments with the oscilloscope.

Marantz 2500 Recovery Documentation

Final Photos of Marantz 2500 Restoration

Presents final visual documentation of the Marantz 2500 recovery process.