Marantz 510M Vintage Stereo Power Amplifier

Marantz 510M stereo power amplifier, offered by Vinyl Vogue following documented repair, capacitor replacement and functional testing. This 1970s solid-state design combines dual power meters, individual channel level controls and fan-assisted tunnel cooling.

Condition

Used vintage condition. The supplied front photograph shows surface marks and haze or smudging on the dark meter window, with light marks on the silver faceplate. These details have not been retouched. No mint-condition claim is made.

The interior and amplifier-board photographs document work during service; they are not photographs of the completed exterior.

Documented service

• All eight output transistors on one channel were replaced: four MJ21196G NPN and four MJ21195G PNP devices. The opposite channel retains its original output transistors.
• Replacement outputs were screened with handheld hFE and Vbe checks.
• Electrolytic capacitors on both amplifier boards and the main power-supply filter capacitors were replaced.
• Two damaged adjustment trimmers on one amplifier board were replaced, followed by bias and DC-offset adjustment.

Functional testing

The completed service record reports 0 mV DC offset on both channels after warmup, bias readings of 25 mV on both channels, and good speaker listening results for both channels. Relay engagement was observed during service. No measured full-power output or distortion result is supplied. This work is described as repair and servicing; a complete restoration is not claimed.

Published specifications

• Factory rating: 256 watts per channel into 8 ohms, both channels driven, 20 Hz–20 kHz, at no more than 0.05% total harmonic distortion.
• Factory 4-ohm rating: 350 watts per channel at no more than 0.10% total harmonic distortion.
• Input impedance: 25 kΩ; input sensitivity: 2.26 V RMS for rated 8-ohm output.
• Published chassis dimensions: 15⅜ W × 6⅛ H × 14 D inches; approximate unpacked weight: 46 lb.

These are original model specifications, not new measurements of this particular amplifier. A separate preamplifier is required.

Included, shipping and pickup

The component shown is the item offered. Other audio equipment and shop items in the background are not part of this listing. No additional accessories are promised.

Local pickup is available at Vinyl Vogue in Ellsworth, Maine. Contact the shop to arrange a time to inspect the unit. UPS Ground shipping to the contiguous United States is calculated at checkout from the package dimensions, shipment weight and delivery address, with a 5% handling adjustment. Shipments will be insured for the purchase value and require a signature. A street address is required; UPS does not deliver to PO boxes.

If purchasing both Marantz components together, contact the shop before checkout so we can quote the two separately packed boxes and send a combined invoice.

The description distinguishes documented service and testing from original factory specifications. Please review the photographs and ask about any detail important to your system before purchasing.