Sunday, January 7, 2018

K. McGonigle Sansui 5000X

Sansui 5000X Receiver



Here were are showing another Sansui 5000X series Receiver that came in for restoration. The 5000 series was available in different version thru different years with the 5000 (1967), 5000A (1969) and finally the 5000X reportedly in 1971. 


The latter version contain the F10401020 Driver assemblies, which are extremely notorious for overheating and destroying output devices, a significant service bulletin was released replacing this design with the F-6013 driver PCB’s which remedied the cascade bias issues of the early version. This particular unit had the 6013 drivers already installed from factory.


F-1137A Ripple Filter
The Sansui 5000X uses a secondary fed regulated supply, the original supply uses a large format TO-66 device that tends to dissipate significant heat as well as a TO-39 device near a wire wound resistor thats susceptible to higher heat with its package materials.

The electrolytic capacitors were replaced with a high temp (105) long life Nichicon PW and Panasonic FC type capacitors with an increase in operating voltages. Original rectifier diodes were replaced with a Ultra-Fast UF400# series axial Fairchild diodes.  The TO-39 2SC device was replaced with a modern heavy duty OnSemiTO-126 device for better dissipation and handling. The chassis mounted 1000MFD was also replaced with a high temp (105C) Nichicon computer grade capacitor. 


BEFORE


AFTER



F1042 Diode Stack
The bridge rectification stage with the 2200MFD filter capacitors separates the a pair of secondaries for the B+/- supplies.

 One of the MAJOR upgrades performed on this unit was the removal of the old bridge rectifier and installation of a custom built Ultra-Fast Bridge Rectifier using heavy duty UF, Soft Recovery Axial Vishay diodes


The electrolytic capacitor was replaced from a axial to a reliable radial, high temp (105C) Nichicon PW capacitor with an increase in operating voltage. The TO-39 2SC device replaced with a high gain, ultra reliable ZTX TO-92 device. The two coupling .01 films were replaced with a high grade  ECW polypropylene 630V film capacitors



BEFORE


AFTER


Confirming the AC/DC Regulation


Filter Capacitors
The schematic indicates the use of 1500MFD capacitors when 2200MFD are actually used. The X4 2200 capacitors were replaced with high grade Nippon Chem-Con 2200MFD 100V filter capacitors.Great care is taken to use small profile capacitors here as the TO-66 drivers tend to radiate significant heat.




The 1000MFD chassis mounted capacitors was replaced with a high temp (105C) Nichicon 1000MFD capacitor with an increase in operating voltages. 

F-6013 Drivers
 As noted in the introduction above the original 5000 series utilized a series of different drivers where the thermally couple driver stage would cause a bias cascade and exhibit heat issues.  Sansui released Service Bulletin CE-037A which included details on the new F-6013 driver design to be installed on effected units, additional power supply changes are required.

On these drivers the electrolytic were all replaced with a low impedance and audio grade Nichicon PW and KT with an increase in operating voltages. The original input and mylar films were all replaced with a high grade WIMA polypropylene film capacitors.   The original open frame potentiometers were replaced with precision 500mW Bourns trimmers.

Some of the F-6013 feature a different differential NPN wether a 2SC984 or 2SC1000 device which was replaced with a low noise modern TO-92 Fairchild NPN device. The original TO-39 requires a high gain device, a high grade ZTX type TO-92 NPN device was installed in place. 


BEFORE


AFTER




Bias Confirmation New Bias notations at the emitter resistor (x1) for (.33ohmX26mA=8.3-8.48mV RXI=V)

CLIPPING SYMMETRY Confirmed

F1350 Tone
The AF stage on the 5000X is frankly nothing short of a mess with many poor connections of free wire hookups and very high gain 2SC NPN devices. 

The electrolytic were replaced with a low impedance Nichicon PW and audio grade KT capacitors with an increase in operating voltages. Low microfarad capacitors and mylar film were upgraded to a high grade WIMA polypropylene film capacitor. 


BEFORE

AFTER



As noted on a prior 5000X we did;
The 2SC871 small signal transistor can be a very tricky device to cross reference as this circuit requires significant gain, the high hFE of the original device is typically at least 450hFE. New ZTX high grade NPN TO-92 were used with a higher gain class than the typical 1845 compliment usually utilized.

F1036A RIAA EQ
The RIAA EQ is contain in a shielded enclosure along with the selector path switch and a large 470MFD capacitor which was replaced with a 470MFD Nichicon PW capacitor. 


Some of the F1036A used the failure prone 2SC458 and others are populated with a 2SC632 NPN (2SC871) devices. All of the original small signal NPN TO-92’s were replaced with a modern low noise TO-92 Fairchild devices.  The electrolytic capacitors were replaced with low impedance PW and audio grade KT capacitors with an increase in operates voltages. Small value capacitors were replaced with a high grade WIMA polypropylene film 
capacitors. 


BEFORE


AFTER



RF AM/FM (F-1006-2/ F-1083-5/ F-1219/1120)
This assembly is not properly notated with the service manual, but documented within the schematic view. Like the remaining RF stages the electrolytic were replaced with a low impedance Nichicon PW capacitors with an increase in operating voltages. The 2SC458 failure prone device was replaced with a modern low noise Fairchild TO-92 device. Below is a comparable view of a pre-eminent failing 458 device. 






New custom multi-SMD LED’s installed



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Tuesday, January 2, 2018

KJ Bleus' Marantz 2325 Receiver

Marantz 2325 Receiver W/ BA312 Upgrade Modules



The Marantz 2325 is one of the most popular Marantz receivers, and has remained so for decades. This longevity was achieved thru its superior build quality, pre-amp stage and reliable nature. I often recommend the 2325 and 2275 series as they feature a similar and unique quality in the latter 22/23XX series. This particular 2325 in for restoration also received our proprietary BA312 upgrade in the PE01 pre-amp stage!



P800
The 2325 P800 assembly regulated power supply establishes the single-ended 14 and 35V supply rails via a Full-Wave rectification array, a Full-Wave rectified supply also enables a onboard protection circuit responsible for DC deviation and over-current protection of the output stage. The 60V rails are established via a Full-Wave Bridge array and two 15Kmfd filter capacitors. The PCB must be cleaned extensively as old glue can oxidize component legs, causing failures. Below is this PCB after removing all the old glue;


All of the electrolytic capacitors were replaced with a high temp (105C) low impedance Nichicon PW with an increase in operating voltages, the initial decoupling and remaining application capacitors were increased to 1000, 330 and 22MFD capacitors for better dc filtering. Common cathode diodes were replaced with Ultra-Fast, Soft Recovery MUR type  TO-220 devices, bypass films were upgrade to a ECW type polypropylene Panasonic. 



BEFORE

AFTER


TO-220 regulators were updated to a modern, more robust TO-220 type TIP devices with new synthetic performance Wakefield compound applied. Remaining TO-92 devices were replaced with modern low noise Fairchild TO-92L devices with better dissipation. A precision Bourns adjustment potentiometer installed and a new Omron DC24V relay installed.


35V Regulated Supply Confirmation

Both 15,000MFD filter capacitors were increased to 18,000MFD computer-grade Nippon Chem-Con capacitors for better filtering/PS reserve.



PH01—>PE01
The PH01 buffer assembly essentially processes input via the function and converted to a low output impedance source. 

The electrolytic on this assembly were replaced with low impedance Nichicon PW and audio-grade KT capacitors with an increase in operating voltages. The films in this stage were updated to a high-grade WIMA polypropylene film capacitors. The varistor was updated to modern 4148 type diodes in series and all remaining small-signal devices were updated to low noise Fairchild TO-92 and TO-92L type devices. A resistor was replaced as well, as some technician prior has simply put two in series for the correct value...lazy


BEFORE

AFTER


PE01 W/ BA312 AE UPGRADE
The original BA312 integrated-circuit (IC) is a old, early pre-amplifier IC device used as a gain stage in many of the PE01 pre-amp designs including Sansui variants. With great advances in todays high-end operational-amplifier (OP-Amps) we were able to design a circuit that allows for integration of a op-amp into the original BA312 location with no cutting or hacking…and no messy/noisey extra PS rails. 

For additional information on the BA312 upgrade please visit the Analog Esoteric website @ 


All of the electrolytic capacitors here were replaced with a audio-grade Nichicon KT/KA type, the decoupling capacitor was increased to a 470MFD low impedance PW for better dc filtering, all with an increase in operating voltages. The output bipolar were replaced with a audio-grade Nichicon MUSE BiPolar type. Input and all coupling films including electrolytic at 1<MFD were all replaced with a high-grade WIMA polypropylene type film capacitors. Lastly the original BA312 IC’s were both removed and replaced per instructions with the Analog Esoteric BA312 Upgrade Module pairs.

BEFORE


AFTER



P400 RIAA EQ
Like the PE01 pre-amp stage the P400 phono stage is another very popular design used in many of the 22/23XX series receiver.  The P400, with our proper upgrades has a very linear and accurate RIAA Curve response.

The decoupling 220MFD filter capacitor was increase to a 330MFD in a more reliable radial package designed, low impedance Nichicon PW, remaining electrolytic were replaced with a audio-grade Nichicon KT all with an increase in operating voltages. The original tantalum was replaced, along with the inputs to high-grade WIMA polypropylene films. The varistor and associated diodes were replaced with modern fairchild 4148 type, the failure prone 2SC458 and remaining small signal devices were replaced with low noise Fairchild TO-92 devices. Both clipping adjustments were replaced to precision Bourns potentiometers. 


BEFORE


AFTER





P700 Drivers
The 2325 uses a differential gain stage and current stage which drives the eventual pre-drivers, the drivers are tied to the dynamic bias circuit. 

The differential pairs were matched with 2% and thermally coupled together with beta mapping notated below for confirmation. Remaining devices to pre-driver were updated with modern Fairchild TO-92 and TO-92L type devices.  As I’ve mentioned these type of pots before on Marantz I recommend cleaning them versus replacement and ensure tracking.  The diode service bulletin addressed as well. 


Beta Mapping

The electrolytic capacitors were replace with a audio-grade Nichicon KT including replacing the 33MFD tantalum to KT, all with an increase in operating voltages.  All of the input and bypass films were upgraded to a high-grade WIMA polypropylene type film capacitors.


BEFORE


AFTER







Bias Confirmation

RF 
Remaining key RF stages including Dolby Noise Reduction had their respective electrolytic capacitors replaced with low impedance, high temp (105C) Nichicon PW and Panasonic FC capacitors with an increase in operating voltages.


BEFORE

AFTER


DOLBY NR 




Lamps & LEDs
Like most units, this customer left us a surprise of a totally destroyed lamp housing. As we've mentioned dozens of times, you CANNOT use old incandescent type lamps in these vintage units. It utterly melts and destroys the plastic shroud. In this case a old-stock replacement shroud was installed and the original broken plastic removed. New Vellum paper and New Meter Vellum paper was installed. 







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