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. Also Dismounted P.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.
-Pulled both meters out of circuit and tested them individually using laboratory grade signal generator
-Cleaned and exercised all switches and board trimmers three times with Deoxit D5, and then applied Deoxit D100 to prevent future oxidation
-Calibrated meter strength, amp Bias, and DC offset
-Final bench test: 3hr

From the owner's manual -

Marantz 250 Stereo Power Amplifier (1973-74)

Specifications
Power output: 125 watts per channel into 8Ω (stereo)
              150 watts per channel into 4Ω
Frequency response: 2Hz to 100kHz
Total harmonic distortion: 0.1%
Damping factor: 100
Input sensitivity: 1.5V
Signal to noise ratio: 106dB

Ships worldwide, or local pickup can be arranged. Quoted international shipping rate is to Australia, the furthest destination from my location in the USA. Please inquire for shipping rate to your particular non-US address.

The package will be large, heavy, delicate, and will be insured for full value under Reverb Safe Shipping, so shipping may be a significant expense.