Thursday, November 26, 2015

Marantz Model 112 AM/FM Tuner


Here we've got a nice Marantz Model 112 Tuner, produced during 1975 to 1978, pairing mostly with the 140 Power Amplifiers (Special thanks to Vintage-Marantz Mr. Lierke for that info) The Model 112 uses heavy weight painted shielding which is a great option to see, this helps cutback on excessive RF noise and feedback.

P400 Power Supply
All electrolytics here were replaced with high temp (105C) long life Panasonic FC's. One issue to note is the 330 microfarad capacitor had excessive glue used when populating the boards during construction. This glue has spread to several carbon composite resistors which we highly recommend replacing, any interacted component with glue. 

P200/300 FM/AM Assemblies & PT01 Switching
Like most RF stages we do, Nichicon PW, low impedance, high reliability capacitors were utilized throughout. Note their are some oddball BI-Polar values used in this section. The mono/switching PCB has one 47 microfarad capacitor, replaced again with a PW.

New LEDs were added, I should add this is one of the easiest models to do a conversion on, but like most encountered the bi-pin function lamps needed resoldering. I think the excessive heat generated by the incandescents cook the solder joints here.

All in all, a very nice little tuner with excellent reception, I highly recommend em'. 

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