S.Kinder's Yamaha CA-610 MKII Integrated Amplifier Restoration

Yamaha CA-610 MKII Integrated Amplifier

Produced in the late 70’s after 77” the Mark II variant featured a 50 Watt output at .05%THDN. The CA-610MKII utilizes a cost-effective single main PCB design for most of the PS and AF front end stages with calibrated meter output.

Regulated Power Supply & Protection

The regulated power supply is contain on the single main large PCB of the unit. A full-wave rectifier bridge is employed for the -/+B source and a simplified full-wave for the AF/RIAA front end supply. The protection stage is also contained therein which monitors thermal run-off and DC deviation of the output stage.

The simplified rectifier array was replaced with ultra-fast, soft recovery dial Vishay diodes. The TO-220 regulator was replaced with a modern, robust TIP device thermally coupled with synthetic thermal compound, remaining small signal devices were replaced with modern, TO92/(L) type Fairchild devices. 

Bypass capacitors were replaced with Nichicon polypropylene film capacitors. Remaining electrolytic were replaced with low impedance, high temp (105C) Nichicon PW type with an increase in decoupling stage and operating voltages.  New 10,000MFD computer grade capacitors installed for the -/+B supply.

AFTER

-/+BVdc Confirmation

Main PCB Driver Section

Like the regulated supply the driver stage is housed on the main PCB with symmetric drivers and  complimentary output stage and differential input. 

The common emitter PNP devices were replaced with single discrete matched, low noise TO92 Fairchild devices. All of the small devices were replaced with modern TO-126, TO92L Fairchild devices with better dissipation. TO3 output devices were replaced in complimentary pairs with modern, On-Semi type with new thermal compound applied. New general axial 4148 diodes installed and precision bias potentiometers installed.

Differential Mapping

Electrolytic capacitors were replaced with audio grade KT/KA and low impedance Nichicon PW type with an increase in operating voltages. Ceramic and small value capacitors were replaced with high grade WIMA polypropylene film capacitors.

BEFORE

AFTER

Bias Confirmation

Tone Amp & Controll

The pre-amp, housed also on the main PCB area. Consisting of a simple single-end front end and output stage. The control PCB for tone attenuation is located on a separate PCB perpendicular to the chassis mount. Control hardware including the multi-gang volume/balance potentiometer were removed and properly treated.

The small signal devices were replaced with modern, low noise Fairchild devices. Small value and ceramic capacitors were replaced with high grade WIMA polypropylene film capacitors. Capacitors were replaced with audio grade KT/KA and low impedance Nichicon PW type with an increase in operating voltages. 

BEFORE

AFTER

RIAA EQ (PHONO)

The phono stage is located on a separate plane PCB with the input and selector points onboard.

All of the small signal devices were replaced with modern, low noise TO-126 and TO-92 Fairchild devices. Small value and ceramic capacitors were replaced with high grade WIMA polypropylene film capacitors. Capacitors were replaced with audio grade KT/KA and low impedance Nichicon PW type with an increase in operating voltages. 

BEFORE

AFTER

RIAA Curve Response

Meter Assembly

The calibration point had the original adjustment hardware replaced with precision, sealed Bourns potentiometers. Axial diodes were replaced with general axial 4148 type axial diodes. The original incandscenet lamps were also replaced with cool white LED’s with current drop modifications.

BEFORE

AFTER

AUDIO NOTIZEN

D.Deremo's Marantz 2285B Receiver Restoration

Marantz 2285B Receiver

The 2285B version was the latter 2285 adaptation with additional Dolby options and aesthetics. The 85B was available from mid 1977 to early 1980 with a nominal rating of 85Wrms @ .05%THD. The 2285B employed many of the latter B version build points such as the symmetric driver design.

P800 Power Supply

The dual secondary transformer is inline with dual section filter capacitors and each with its own full-wave bridge rectifier. The Regulated P800 supply utilizes a full-wave bridge and a separate full-wave rectifier array for the protection. 

All of the common cathode, common anode devices were replaced with state of the art Hex Fred ultra-fast, soft recovery MUR series TO-220 rectifiers. The TO-220 regulator was replaced with a OnSemi type modern, robust MJ series device with new synthetic thermal compound applied. All remaining small signal devices were replaced with modern, low noise TO-126 and TO92(L) Fairchild devices.

All of the electrolytic capacitors were replaced with low impedance PW and high temp (105C) Nichicon type with an increase in operating voltages, DC coupling capacitors were also increased in MFD value for better filtering. 

BEFORE

AFTER

Reg. Vdc & -/+B Confirmation

PE01 Pre-Amp

The PE01 employed in the 2285B is a vastly different design than a majority of the PE designs employed by similar Marantz PE01. This stage uses a series of common emitter PNP devices which are noise and failure prone. 

All of the common emitter devices were replaced with beta matched low noise, modern PNP devices in separate TO-92 Fairchilds. Remaining small signal devices were replaced as well with low noise Fairchild devices. 

All of the electrolytic capacitors and .22MFD mylar were replaced with a audio grade KT/KA and low impedance PW Nichicon capacitors with an increase in operating voltages. Mylar and 1MFD capacitors were replaced with a high grade WIMA polypropylene film capacitors. 

BEFORE

AFTER

P400 RIAA EQ (PHONO)

The phono stage is the similar concept to the Marantz 22XX series with a contained selector plus an additional FB stage.

All of the small signal devices here were replaced with a low noise Fairchild devices. All of the input capacitors were replaced with a bipolar audio grade MUSE Nichicon capacitors. Remaining capacitors were replaced with audio grade KT/KA Nichicons and the DC coupling capacitors increased for better filtering and replaced with a low impedance PW type, all with an increase in operating voltages. 

BEFORE

AFTER

RIAA Curve Response

P700 Driver

The 2285B driver is composed on a single symmetric PCB design with a shared complimentary output stage and convenient molex connection points. 

The differential pair transistors were beta matched and thermally coupled together. All remaining pre-drivers, drivers were all replaced with modern, robust TO-220 MJ series OnSemi and TO-126 Fairchild devices all thermally coupled with synthetic thermal compound. New precision Bourns potentiometers were installed for bias/offset adjustments. 

Differential Mapping

The input capacitors were replaced with audio grade MUSE bipolar Nichicon capacitors along with remaining capacitors as low impedance Nichicon PW type with an increase in operating voltages. Remaining film capacitors were replaced with a high grade WIMA polypropylene film capacitors.

BEFORE

AFTER

Bias Confirmation

RF Front End

All of the RF capacitors were replaced with a low impedance Nichicon PW type with an increase in operating voltages.

BEFORE

AFTER

AUDIO NOTIZEN