Wednesday, October 5, 2016

Marantz 2330BD Receiver Restoration

Marantz 2330BD Receiver

Today were showcasing a Marantz 2330BD Receiver. Produced during the latter 77-79 years the 2330BD is similar to the 2330B with the addition of a multi-voltage selector for overseas markets and a Dolby FM Decoder.   These models differ from the 2330 with the integration of a single symmetric driver assembly and ,multi-section filter capacitors and of course Dolby.

P800 Power Supply

 The power supply had a new Omron MY4 installed recently which remained.  The remaining electrolytic were replaced with higher voltage high temp (105C) long life/low impedance Panasonic FC and PW Nichicon to better withstand the offset temperatures within the power supply. Diodes upgraded to modern 4148 or ultra-fast 400# series. The original common-cathode/anode devices were replaced with higher capacity, more robust MUR1620 series TO-220 devices.  The 2330BD uses a dual section fitter capacitor array for each rail/channel, these were restored with 7200/100V computer grade CDM Cornell capacitors. The bridge rectifiers were updated with high grade MKP polypropylene film capacitors at .1MFD

P700 Driver Assembly
The driver assembly comprised on a complimentary PP output section is mounted to a single sink with a symmetric topology.

The initial differential pair transistors were replaced with new lose noise TO-92 1845 transistors thermally coupled and matched to 1% along with the regulating transistors to the above.  The pre-drivers were also replaced with modern more robust MJE devices and new thermal compound to their respective heatsinks.  2473 type diodes were replaced with modern 4148 diodes and the robust original potentiometer cleaned and lubricated and tracking confirmed. High grade WIMA and Panasonic ECW were installed in place of the original films and electrolytic replaced with low impedance high temp (105C) Nichicon PW’s.  TO-3’s removed and new thermal compound.

Like many of the latter designs the selector is housed on the same assembly as the EQ stage.  1% matched modern low noise 992 high gain transistors were replaced for the initial gain stage.  The remaining electrolytic were replaced with low impedance long life and audio grade PW/KA capacitors. Below is the only RIAA curve report published online to date we compiled;

RIAA Curve Report

PE01 Tone/Pre & PH01 Filter/Switching

The differential gain stage is comprised of a single package dual device and output, similar PCB design to latter 23XX series except the amount of onboard attenuators housed making for a large footprint PCB.  The electrolytic and tantalums were replaced at 1MFD with high grade WIMA polypropylene films and Nichicon KA audio grade capacitors and two .22 polypropylene ECW film capacitors.

The Filtering and Switching Assembly access is gained after removing the PE01 assembly and the time we cleaned and lubricated each control and switch using Caig Labs D5/F5 concentrates. The electrolytics were replaced with low impedance PW's and high grade polypropylene WIMA Film capacitors. 

RF Sectionals
The RF stage is a separate FM Front end PCB and AM/FM Decoder DBX assembly similar to the 2385+ series more so.  The several bi-polar electrolytic were replaced with .22MFD ECQ stacked films and UPV BP Nichicon. Remaining electrolytic with high temp (105C) KL/PW Nichicon capacitors.

Pre Restoration Performance Report

 Restored Performance Report

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