Technics Concise Component Series (MICRO)
Technics Micro Series was produced during the very late 70’s including the SU-C01 Pre-amplifier, SE-C01 Power Amplifier with correlating SH-C01 Power Plant. Each featured a micro-foot print in production scales. The european versions often were paired with the umbilical and a SH-C01 power plant whereas the exported models used a on board pulse switching power supply fully enclosed.
SU-C01 Stereo Pre-Amplifier
Released in 1978 as part of Technics Micro line the SU-C01 was the attached pre-amplifier. With a modest foot print compared to its era counterparts the SU still delivers impressive performance with almost linear frequency responses and built-in precision MC/mm stages! Build quality was worth noting as well with a quality die-cast chassis and heavier material used, gold plated input hardware and iron cased transformer for reduced intrinsic potential.
Stabilizer Stage
The SU revolves are a single full wave bridge rectification stage filtered by two 1000MFD capacitors and feed thru a regulated output for a dual -/+19V rail supplies for the Phono and Audio Front End (AF) stages. Technics touts their isolated iron transformer enclosure to help prevent intrinsic noise. This assemblage is also related to the Muting/Protect circuit with reed type relay trigger.
The electrolytic capacitors in these stages were replaced with a high temp (105C) low impedance Nichicon PW type with an increase in operating voltage. The VD type varistors were replaced with modern axial Vishay diodes along with associated 20V zener strings. The TO92 and TO126 devices were all replaced with low noise, modern Fairchild devices. The common diode rectifiers were replaced with Ultra-Fast, Soft Recovery Vishay diodes.
BEFORE
AFTER
-/+19V Rail Confirmation
Audio Front End
The simplified gain stage of the SU employed two monolithic 7 pin “M5213L” pre-amplifier IC’s which offer a low noise gain developer with high input variables. The AF front end was combined with dual stepped tone controls for high and lo filters.
The small value electrolytic and bipolars here were replaced with a high grade WIMA polypropylene film capacitors. The DC filtering capacitors were increased to 100MFD for better results and remaining electrolytic capacitors replaced with a audio grade KT/KA and low impedance PW capacitors with an increase in operating voltage. Mylar films were replaced with the above polypropylene WIMA films.
BEFORE
AFTER
Phono Stages (MM/MC)
The SU touted its low noise phono amplifier stage with its built it low input MC stage. The MC stage is composed of a push pull front end and voltage gain output, with a low noise differential, the MM employing a current mirror design. Precision film resistors were used in the original buildup.
The MC section had all of the differentials and small signal devices replaced with beta matched and all new low noise modern Fairchild devices. The capacitors were replaced audio grade MUSE Bipolar and low impedance PW Nichicons, with an increase in operating voltage. DC filter capacitors were increased in this stage to 47MFD per rail.
Beta Matched RIAA Differentials
The MM stage had a similar approach with matched differentials and new low noise modern Fairchild devices. All new audio grade WIMA polypropylene film capacitors and electrolytic capacitors replaced with a audio grade KT/KA and low impedance PW Nichicons with an increase in operating voltage including the large 1000MFD capacitors.
BEFORE
AFTER
RIAA Curve Response
Hardware
During the stripping of the chassis the controls were desolder and Caig Lab products applied to clean and lubricated potentiometers
AUDIO NOTIZEN
Two SE-C01 Power Amplifiers
This customer brought fourth two of the SE-C01 amplifier modules as these can be operated in a monolithic or stereophonic orders via a switch on the bottom of each unit. The SE-C01 was built in two versions; one with the power plant enclosed in the amplifier unit, available to use isolated. The typically euro designated units were paired with the SH-C01 which was a external -/+42V source. The SE also contains and off/on muting and DC deviation protection relay.
These version contained the onboard Pulsed Power Supply modules, which are self shielded in die-cast cabinets, this unconventional design rectifies the AC inline current and converts to a 20Khz square wave which drivers the transformer, hence its smaller form factor to traditional irons. The 470MFD/200V filters for this supply were both replaced with computed grade CDE capacitors.
BEFORE
AFTER
Each of the Pulse Power Supplies were opened and inspected for faults, all of the electrolytic capacitors in each unit were replaced with a high temp (105C), High DC 250V+ low impedance Nichicon PW types.
BEFORE
AFTER
Direct-Coupled (DC) Amplifier
The SE design follows a direct-coupled concept which means no audio or NFB capacitor chains. The core design employs a dual differential stage proceeded by a voltage amp stage, current mirror and pre-driver-output 3rd-4th order design, current limiter protections are also incorporated.
All of the capacitors here were replaced with audio grade KT/KA and low impedance PW type Nichicon capacitors with an increase in operating voltages. Mylar films were replaced with a high grade WIMA polypropylene film including all 1MFD> capacitors. Diode arrays were also replaced with axial general Vishay type. DC Balance and idle adjustments were all replaced with precision, sealed Bourns potentiometers. Current limiter, pre-drivers and voltage stage devices were all replaced with a low noise, modern TO-92L / TO126 Fairchild devices.
BEFORE
AFTER
Bias Confirmation
UNIT #1
UNIT #2
Meter Drive Circuit
The meter is a IC controlled array using a 12-diode Red/yellow display for peak to peak output with a scaling reading for lower output at 16W+ or 100W+.
All of the capacitors here were replaced with a VP Bipolar and low impedance PW Nichicons with an increase in operating voltages. The 10E diode was replaced with a Ultra-Fast Soft recovery axial type and all small signal devices replaced with modern low noise Fairchild TO92L/TO126 type. The To-220 regulator was also replaced with a TIP TO220 device thermally coupled with synthetic Wakefield compound.
BEFORE
AFTER
AUDIO NOTIZEN
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