Marantz Model 250 Stereo Power Amplifier, Pro Serviced Upgraded Recapped LEDs

  

Professionally refurbished Marantz 250 Stereo Power Amplifier, 125 watts per channel, originally available 1973-74. Upgraded caps and LEDs, all amplifier functions tested and reliably performing at or exceeding factory spec. PLEASE NOTE: The meter needles and internal springs sustained light damage that could not be totally corrected, and stick intermittently. Unit does not have feet.

Presents very well cosmetically, with no significant issues. Notes from the technician - Initial assessment: -Right channel distortion -Right meter does not work -All front panel bulbs do not work -Power transformer loose from chassis due to missing hardware -Meter needles and internal springs could not be totally corrected, and stick intermittently Service notes: -Dismounted transformer from chassis, and dismantled both amp channels completely to have clear access to all internal circuitry. S/Protect Board from back panel for access to replace components. Closely checked soldering joints on all boards with high powered magnifying glass and re-soldered 10-15 suspect joints -Thoroughly inspected all boards for burning or corrosion: noticed a positive rail feed resistor that cracked into pieces due to excessively overheating on right channel amp board.

Replaced burnt 39ohm 1watt resistor with 47ohm 1watt flameproof resistor -Removed all transistors from Right channel amp board and tested them individually using Atlas DCA55 transistor tester, and then replaced two slightly leaky current drive transistors. Ohm checked all resistors on both amp channels, P. S/Protection Board, and Meter Drive board: Good -Upgraded all electrolytic caps on both Amp boards to Nichicon gold in audio path and high temp Nichicon low esr for third order filtration -Upgraded all electrolytic caps on P. S/Protection board to slightly higher capacitance value Nichicon low esr, for improved ripple filtration This unit has industrial grade relay that can be cleaned and does not need to be replaced - it will last a very very long time -Buffed relay contacts, tightened relay tension, and loosened spring for more reliable long term contact When inspecting meter drive board noticed incorrectly built circuit from manufacturing line, more specifically a backwards capacitor (see photo #22). This means this unit never fully functioned correctly since it was built!

-Used schematic to inspect all components on meter board, to ensure no more manufacturing mistakes were made: good -Replaced all electrolytic caps on meter board with high grade Nichicon low esr, and corrected the polarity of the cap that was originally in backwards. The item "Marantz Model 250 Stereo Power Amplifier, Pro Serviced Upgraded Recapped LEDs" is in sale since Saturday, October 30, 2021. This item is in the category "Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Amplifiers & Tube Amps". The seller is "andyexcuse" and is located in Andover, Massachusetts. This item can be shipped to United States, Canada, United Kingdom, Australia, Japan, South Korea, Indonesia, South africa, Bahamas, Israel, New Zealand, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Bahrain, Malaysia, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Pakistan, Paraguay, Reunion, Uruguay.

1. Model: Marantz 250
2. Modified Item: Yes
3. Country/Region of Manufacture: United States
4. Custom Bundle: No
5. Type: Power Amplifier
6. MPN: 250
7. Modification Description: Recapped, LED lamps
8. Brand: Marantz