Marantz PM7200 Amplifier Repair



Published
Fault
Amplifier powering on but speaker protection relays not changing over.

The legendary PM7200 is an excellent Amplifier to work on due to its modular construction.

The Amplifier was powered up via the Dim Bulb tester, no excess current draw was seen.

As is the case with all Marantz Amplifiers of this time period dry solder joints form on all the circuit board.

The Amplifier was dis-assembled and the large amounts of dust covering the circuit boards removed, there was no sign of component failure so all boards were systematically re-soldered as required.

Due to the age of the Amplifier the speaker protection relays were replaced to avoid any issues with intermittent loss of Audio at low volume caused by oxidised switching contacts.

Relay specifications 24 V DC Coil DP/CO 5 Amps

The video shows the different circuit boards and also the vertically mounted speaker protection board.

There were dry solder joints on many of the connections pins where the protection board plugs into the power Amplifier Board.

All user controls and switches cleaned with De-Oxit to ensure noise free operation.

Amplifier re-assembled and tested, re-soldering the circuit board had fixed the issue with the speaker protection relays not changing over.

Bias for each channel and DC offset checked no adjustment required.

Amplifier fully tested working correctly.
Category
Audio
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