Electronic refurbishment — all three boards
All electrolytic capacitors across the three circuit boards — Power Supply (PWR-828/830), Drive Control (PWG-011), and Auto-Return Detector (PWX-011) — are replaced as standard. I use Nichicon PW, Nichicon KL, and Panasonic FC series throughout, with WIMA film capacitors where appropriate. These are the same premium-grade components used in professional audio restoration.
Key transistors are replaced on both the Power Supply and Drive Control boards, including the pass transistor, error amplifier transistors, and speed-critical components. Original VD1222 dual diodes are replaced with matched 1N4148 pairs. The zener diode is replaced with a new unit.
Old electrolytic capacitors become leaky with age, causing speed instability, quartz lock issues, and long-term IC damage. Even units that appear to be working benefit from a full recap.
AC side — safety
The four capacitors that sit directly across the mains and microswitch contacts as arc snubbers are replaced with X2 safety-rated film capacitors (275 VAC) — Kemet R46KI series throughout. A 1977 general-purpose film cap in this position can fail short with no downstream protection — X2-rated parts are designed to fail open. This is carried out on every unit without exception. Fuse clips are re-tensioned or replaced, and the power cord and strain relief are inspected.
Power supply — stability
The +B 20V rail feeds both the quartz-PLL drive control and the auto-return logic — its ripple and noise floor matter everywhere. The main reservoir capacitor (C206) is replaced with a new equivalent-value low-ESR 105°C Panasonic FC unit, along with film bypass capacitors for high-frequency stability. A bypass electrolytic is fitted across the zener reference diode, reducing noise directly on the supply rail — zeners are intrinsically noisy and that noise modulates +B directly.
Auto-return detector — timing stability
The auto-return board is the PL-570's known weak point. Detection relies on RC timing circuits built from 1977 electrolytics — the root cause of early, late, or failed auto-return. I address this systematically:
- C105 (the 900ms reference capacitor) replaced with a 5% stacked film part — removing the dominant drift mechanism
- C107 and C101 replaced with film capacitors
- VR101 replaced with a Bourns 3296W-1-471LF sealed multi-turn cermet trimmer (470Ω)
- VR102 replaced with a Bourns 3296W-1-105LF sealed multi-turn cermet trimmer (1MΩ)
- D102 replaced with a 1N4148 — a leaky flyback diode kills relay drive transistors slowly
- Full timing calibration: 900 ±50ms reference verified on oscilloscope, PTr output set to 2.5 ±0.5V
The sealed cermet trimmers replace the original open trimmers which oxidise over time, making calibration unreliable. The multi-turn format allows precise, stable setting.
Drive control board
Recapped at stock values using 105°C low-ESR parts throughout. Speed selector switch and quartz-lock switch cleaned with DeoxIT and exercised. Speed fine-control pot flushed and restored. No value changes are made to loop filter components — the PLL servo design is respected. Connector and header pins between boards are cleaned and re-tensioned.
Timing gearbox
The PTM-12KG cam-drive timing gearbox main gear is replaced with a pro-machined PA12HP Nylon replacement. The original gear cracks at the hub — a known failure point on these decks. PA12HP Nylon is self-lubricating, quieter than the original, and will not stress-crack at the boss.
Strobe bulb
A new strobe bulb is fitted as standard.
Motors
Both the main drive motor and the dedicated timing/auto-mechanism motor are stripped, cleaned, and freshly oiled. Timing motor bushings receive a drop of light synthetic oil at each end. The main platter bearing is drained, cleaned, and refilled with light spindle oil.
Mechanism
All mechanical assemblies — including the full-auto arm mechanism, cam disc, and gear train — are fully degreased using 99% IPA and relubricated with PTFE synthetic grease. Hardened factory grease is the root cause of most stalled or dead auto-mechanism complaints and places excessive load on the timing motor. The arm elevator damper is recharged with silicone damping fluid for a slow, controlled descent. Headshell leads are replaced with fresh OFC leads as standard.
Four critical gaps — factory specification
- Arm elevator height — 8mm stylus-tip-to-record with elevation lever up
- Record size selector — lever F to white plastic edge at SIZE 30
- Lever B to Lever C clearance — 0.5–1mm, unit off
- Output shorting switch S1 contact gap — 0.5mm, unit off
Cabinet — real wood veneer
The original vinyl wrap is removed and the plinth is re-veneered in real hardwood. The wood is hand-finished with a beeswax and linseed oil matt coating, bringing out the natural grain without the plasticky sheen of lacquer. All metal fittings are cleaned and polished. Wenge, Ash, Sapele, and other veneers are available depending on the commission.
RCA output plate — gold plated
The original hardwired RCA signal cable and power cable are removed and replaced with a custom gold-plated RCA phono connector plate, mounted on a carbon fibre panel on the rear of the plinth. This allows the use of any high-quality interconnect of your choosing. Ground terminal included.
Dust cover
A brand new custom dust cover is fitted to every unit — crystal clear, with no yellowing, crazing or haze.
Final verification — every unit
✓ +B rail 20V ±0.5V, ripple below 20mV
✓ Auto-return timing 900 ±50ms verified on oscilloscope
✓ Speed stable on strobe at 33⅓ and 45 RPM with quartz lock
✓ Wow and flutter measured with meter
✓ All five operating modes — 3 clean cycles each
✓ Audio checked across both channels, no crackle through S1
✓ X2 safety caps confirmed, fuse values verified
✓ Tested across multiple records before listing
