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Marantz 2500 Service Manual

Marantz 2500 Service Manual

Toroidal transformer
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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:

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Summary of Contents for Marantz 2500

  • Page 1 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".
  • Page 2 In the above schematic, the toroidal transformer has two secondaries for supplying the power amplifiers (one for each channel) and three additional windings to supply the other components, which are connected to the P800 board. Below is a photo of this board: Note that this board has its original capacitors, as they hadn't yet been replaced at the time of the photo.
  • Page 3 However, I have two machines, a 2600 and a 2500 - both came with the following color sequence installed: Blue Blue Green Green Purple Yellow Brown Blue Gray A quick search on the Internet Green shows the colors in this same sequence.
  • Page 4 The 180V circuit is used to adjust the focus of the oscilloscope, ranging from 50V to 250V. This circuit is derived from the Marantz 4400. The current of each circuit is indicated on the board. Thus, the analysis is complete this side of the toroidal...
  • Page 5 Toroid Specifications – Marantz 2600 Blue Blue (8v) Color Blue Lamps Green Filament Green (6.3v) (8v) Purple Oscilloscope -576 Purple (430v) Yellow Brown Oscilloscope Yellow (CT) Blue Oscilloscope (8v) Brown (160v) Grey Receiver +/-40 (8v) Green Receiver +/-40 Blue (160v)
  • Page 6 Now that our toroid specifications are ready, we have two options: rewind the original transformer or have a new one built. Both options have their advantages and disadvantages. Rewinding the old transformer requires a good technician who knows toroidal transformers, and is careful and be patient enough to remove the existing resin and reuse the same core and housing.
  • Page 7 AC - 6.3V between the orange wire and brown. 8v (AC) between the green & black wires DC - (+ -) 576v between the orange & black wires and brown & black wires. Reassembly continues with the base of the transformer and the power module:...
  • Page 8 View of the new transformer and electrolytic capacitors of the power module, connected to the P800 board: Aluminum base for mounting the new transformer. The transformer base is reattached to the receiver, using the same screws and connections, plus the aluminum base for the new transformer: Finalizing the connections (soft start and thermostats):...
  • Page 9 Last check before pressing the "Power" button: (now a nervous moment - will there be a burning smell? Will we "roast" a component?) Now comes the crucial moment: "May destiny be kind! Time to close the eyes and connect ... ” As the French would say, 'Voilà'.
  • Page 10 Tuning FM Radio: Turning on the oscilloscope and making final adjustments. Everything appears to be in order.
  • Page 11 For the Marantz 2500, just change the voltage of the amplifier outputs. The transformer schematic is below: Toroid Specifications - Marantz 2500 Blue Blue (8v) Color Blue Lamps Green Filament Green (6.3v) (8v) Purple Oscilloscope -576 Purple (430v) Yellow Brown...
  • Page 12 And photos of my Marantz 2500 recovery:...

This manual is also suitable for:

2600Sansui g9000