The Collins S-Line — comprising the 32S-1, 32S-3, 32S-3A, 75S-1, 75S-3, 75S-3B, 75S-3C, 516F-2 power supply, and associated accessories — represents the pinnacle of 1960s amateur radio engineering. Decades of use leave cabinets scratched, dented, repainted in the wrong colours, or stripped entirely. A proper cosmetic restoration is no small undertaking, but when executed correctly it can move a set from “Good” to “Excellent” on the CCA scale and significantly increase both collectability and value.

This guide addresses sheet-steel cabinets (the wrap-around outer shell), front panel assemblies, aluminium bezels around the tuning dial and meters, dial escutcheons, nameplate hardware, and all associated trim strips and fastener hardware. Chassis restoration (internal metalwork) is beyond scope here.

Which Units Are Covered

• 32S-1 / 32S-3 / 32S-3A transmitters — identical cabinet profile
• 75S-1 / 75S-3 / 75S-3B / 75S-3C receivers — identical cabinet profile
• 516F-2 power supply — taller cabinet, same paint specification
• 312B-5 speaker console — wood veneer cabinet, separate procedure applies
• 30L-1 amplifier — larger format, same metal treatment process
• 30S-1 amplifier — wrap-style cabinet with integrated top cap

The Collins Collectors Association defines seven condition grades for used Collins amateur equipment. These standards are authoritative for all CCA net and Reflector transactions. A properly executed cosmetic restoration can move a cabinet from “Good” or “Fair” to “Very Good” — potentially “Excellent” if the finish quality is exemplary and all original hardware is present and correct.

Source: collinsradio.org — CCA Grading Standards

Optional Power Equipment

• Random-orbit sander with dust extraction (160+ grit final stages only — cabinets are thin gauge steel)
• Air compressor with HVLP or siphon spray gun (0.8–1.0mm nozzle for base coat; 1.4–1.8mm for texture)
• Heat gun (wrinkle activation — see Section 9)
• Abrasive media blaster (walnut shell or glass bead) — ideal for heavily corroded pieces
• Ultra-fine wire wheel on bench grinder (rust spot treatment only — keep away from painted surfaces)

Proper disassembly protects irreplaceable components and ensures nothing is scratched during the stripping and painting phases. The S-Line uses a mix of JIS (Japanese Industrial Standard) and standard Phillips fasteners — using incorrect screwdrivers is the leading cause of damaged screw heads. Obtain proper JIS drivers before starting.

Knob Removal

1. 1Place the unit on a padded, non-marring surface. Remove power and discharge all capacitors per the service manual procedure.
2. 2Collins S-Line knobs are retained by a 3/32″ Allen (hex) set screw on the underside of each knob skirt. Locate and loosen — do not remove fully. Rotate knob to expose the set screw via the gap between knob and panel.
3. 3Slip a splined knob puller under each knob skirt (or use two wooden ice-cream sticks as pry levers with masking tape protection) and draw the knob straight off the shaft. Never rock or twist.
4. 4Bag each knob individually in a labelled zip-lock bag corresponding to its panel position. The main tuning knob and bandswitch knob are not interchangeable between models.
5. 5Remove the S-Meter pointer carefully — it is press-fitted and extremely fragile. A small plastic wedge or flathead held behind the base is safest.

Front Panel Removal

1. 1The front panel is secured to the chassis by six to eight #6-32 machine screws around the perimeter. These are JIS type on most production runs — use JIS #2 driver.
2. 2The panel has a multi-conductor interconnect harness and several coax jumpers. Label each connector with masking tape before disconnecting.
3. 3The dial assembly (drum-type on the 32S/75S) is attached to the panel and must be carefully moved forward with it. Support the dial assembly throughout panel removal — do not allow it to drop or torque.
4. 4Set the front panel face-down on a padded surface. Place foam padding between the panel and work surface to protect the dial face silk-screening.

Cabinet Removal

1. 1With the front panel removed, the wrap-around sheet metal cabinet is held by four or six screws along the bottom rail and two screws at the rear panel. Remove all.
2. 2Slide the cabinet forward and off the chassis. Note any rubber grommets at the rear panel cable entry points — collect these and store with the cabinet hardware bag.
3. 3Remove the top cover (if separate) — typically two screws at the front and two at the rear.
4. 4Remove all remaining trim strips, the bottom tray (516F-2), and any rubber feet. Store feet in a labelled bag — original rubber feet in good condition are worth preserving.

Bezel & Escutcheon Removal

1. 1The main tuning dial bezel on the 75S/32S is an extruded aluminium ring secured by three or four #4-40 screws from the rear of the panel. Remove screws and gently flex the bezel free.
2. 2The meter bezels are typically press-fit aluminium retaining rings. A thin plastic spudger around the perimeter will release them without scratching the panel.
3. 3Frequency dial covers (clear acetate or glass) should be bagged separately and cleaned with plastic-safe cleaner only. Avoid IPA on acetate covers — it will craze them.
4. 4Remove all nameplate hardware — the “Collins” badge and model designation plates. These are typically secured by two small screws and should be stored safely.

The goal is complete removal of all previous finish down to bare metal without damaging the underlying sheet steel. The S-Line cabinet is formed from relatively thin-gauge steel (approximately 18–20 gauge) — aggressive media blasting can distort panel geometry and is best avoided except on heavily corroded pieces.

Chemical Strip Method (Recommended)

1. 1Work outdoors. Apply a thick coat of Klean-Strip Aircraft Remover or Jasco Premium Paint Stripper with a cheap paint brush. Apply liberally — thin coats don’t work. Cover with plastic sheeting and allow 20–45 minutes dwell time.
2. 2The original wrinkle finish will begin to bubble and lift. Use a plastic body filler spreader (never metal) to scrape off the lifted material. Metal scrapers risk gouging the steel substrate.
3. 3Re-apply a second coat to stubborn areas. In corners and recesses use a natural-bristle brush (nylon dissolves in methylene chloride) to work the stripper into tight areas.
4. 4Neutralise the stripped surface with a water rinse followed by a wipe-down with 3M PrepSol or similar wax and grease remover. Dry immediately with a heat gun to prevent flash rust.
5. 5For residual texture fragments in the weave pattern, a maroon Scotch-Brite pad with lacquer thinner will remove them without scratching the steel.

Media Blasting (Alternative)

Walnut shell media (40–80 mesh) is safe for thin sheet steel. Glass bead (100–120 mesh) provides a fine, uniform anchor profile ideal for primer adhesion. Avoid aluminium oxide or steel shot — both are too aggressive for cabinet panel work. After blasting, prime within 30 minutes to prevent surface oxidation.

Rust Treatment

Isolated rust spots should be treated with Ospho or Metal Ready (phosphoric acid rust converter) prior to priming. Apply per manufacturer instructions, allow to dry to a white zinc-phosphate residue, and wipe off the excess. Do not use rust converters that leave a black tannic acid residue under automotive primers — adhesion problems will follow.

Surface prep determines whether the final restoration is “Very Good” or merely “Good.” Any dent, hole, or surface defect that is not addressed now will telegraph through the topcoat — even a heavy wrinkle finish cannot hide significant bodywork defects.

Dent Repair

1. 1Minor dents (under 10mm) with no crease: use a hammer-and-dolly technique from inside the cabinet. Work the perimeter of the dent inward, not the centre first.
2. 2Apply Evercoat Metal Glaze or 3M Acryl-Green Spot Putty to low spots. These are thin-spreading finishing putties — not a substitute for structural body filler on large damage.
3. 3For deeper dents: apply 3M Bondo, mix to a uniform colour, spread in a thin layer (maximum 6mm build per coat), and allow to cure 20 minutes at room temperature.
4. 4Block sand with 80 grit on a rigid sanding block, working down to the steel at the filler edges. Follow with 180, then 220 grit. The filler surface should be feathered to zero edge thickness — no “hump” at the filler boundary.

Non-Original Hole Filling

Extra holes (from unauthorised modifications, mounting adapters, or damage) must be filled. From the inside, back the hole with a small aluminium patch bonded with PC-7 epoxy. From the outside, fill proud with body filler, sand flush, and prime. On front panels, consider a professional body shop for TIG brazing — body filler on front panels can crack if the panel flexes during knob installation.

Final Cleaning Before Prime

1. 1Wipe all surfaces with 99% isopropyl alcohol on a lint-free cloth. Allow to flash off (2 minutes).
2. 2Follow with an acetone wipe using a fresh cloth — acetone removes silicone and wax contamination that IPA may miss.
3. 3Tack-wipe with a quality tack cloth (folded to expose a fresh surface each pass). Do not press hard — tack cloths should barely graze the surface.
4. 4Immediately proceed to primer — do not allow bare metal to sit more than 30 minutes after final prep.

A two-stage primer system provides the best foundation for texture topcoats. The self-etching primer bonds chemically to bare steel; the high-build surfacer fills surface texture and provides a sanding base.

Stage 1 — Self-Etching Primer

• Product: SEM Self-Etching Primer (aerosol or spray gun) or 3M 05917
• Apply 2 light coats, 10-minute flash between coats
• Do not sand self-etching primer — sanding removes the chemical bond mechanism
• Allow 1 hour dry time before top-primering
• Note: self-etching primer is green-tinged — this is normal

Stage 2 — High-Build Surfacer

• Product: USC Spray Max 2K High Build Primer (aerosol 2K activated) or Eastwood 2K Urethane Primer
• Apply 3 medium coats with 15-minute flash between coats
• Allow to cure 2–4 hours (60–70°F ambient)
• Block sand with 320 grit, followed by 400 grit wet (optional for ultra-smooth areas)
• Spot-fill any remaining low spots with glazing putty, sand to blend
• Final tack wipe before topcoat

The Collins S-Line cabinet colour is one of the most discussed topics in the restoration community. The correct colour name is St. James Gray — the standard Collins factory designation used across the S-Line era and documented consistently by the restoration community. The S-Line and the R-388 are both St. James Gray but are not the same shade — do not use R-388 paint references for the S-Line. Getting this colour right is the single most important cosmetic decision in an S-Line restoration.

Wrinkle vs Leather Texture Finish

The S-Line cabinet wraps use a wrinkle finish. The front panel uses a distinctly different leather-grain texture — Art Collins specifically modelled this on the tactile finish of his Leica camera. The two surfaces are visually and physically different products. Do not apply wrinkle finish to the front panel, and do not apply leather-texture finish to the cabinet. Matching the front panel leather grain is one of the more demanding aspects of a full S-Line cosmetic restoration.

Wrinkle Finish Application

Wrinkle-finish paint (VHT Wrinkle Plus or equivalent) achieves its characteristic texture through a controlled skin-over followed by heat activation. Technique is critical — incorrect application produces a mottled, irregular wrinkle or no wrinkle at all.

1. 1Temperature matters. Ideal ambient temperature is 65–80°F (18–27°C). Below 60°F the wrinkle will not activate properly. Warm the part with a heat gun to approximately 90°F before first coat.
2. 2Apply a heavy first coat — significantly heavier than a standard topcoat. The paint should be wet and thick, not a mist coat. Allow 5 minutes skin-over time (surface will start to dull).
3. 3Apply a second heavy coat. The texture begins forming as the lower coat skins differently from the upper wet layer. Allow 10 minutes.
4. 4Heat activation: Using a heat gun at 400–450°F setting (or an oven at 200°F for smaller parts), apply heat evenly across the surface from approximately 6 inches away. Move continuously — spot heating creates burnt rings. The wrinkle pattern will fully develop within 2–3 minutes of heat exposure.
5. 5Allow the part to cool fully before handling. Full chemical cure takes 24 hours at room temperature.

Front Panel — Leather-Grain Texture

The S-Line front panel leather-grain finish is one of the most distinctive cosmetic features of the set and the hardest to replicate authentically. The original finish was applied at the factory using a process that produced a consistent fine leather-grain pattern across the entire panel — the same visual character as the textured grip panels on a Leica rangefinder camera.

• Do not use wrinkle-finish products on the front panel — the grain pattern is fundamentally different from a chemical wrinkle
• Leather-grain aerosol products (such as Duplicolor Vinyl & Fabric Coating or equivalent leather-texture rattle cans) are the most accessible approach for touch-up work
• For a full panel repaint, a leather-grain texture roller applied over a wet basecoat is the closest method to factory production technique — apply to a test panel first
• Surplus Sales of Nebraska stocks Collins front panel paint — this is the most authentic source and should be the first option before attempting any alternative
• Apply two medium coats with 15-minute flash between. Maintain a consistent distance (10–12 inches) and speed for uniform grain across the full panel width
• Do not sand or buff the topcoat — the texture is the finish

Masking for Partial Repaints

If only touch-up or localised refinishing is being performed (rather than a full strip and repaint), blend the edges using a dry-mist feathering technique. Apply fine-line tape to the boundary area, then double the tape with standard painter’s tape. Feather the edge by misting over the tape boundary — full wet coats to the tape edge will create a visible step when the tape is removed.

The aluminium bezels, dial escutcheons, and trim strips are anodised aluminium and should never be painted. Polishing restores the original satin-bright appearance. Severely pitted or corroded bezels may need professional re-anodising — a service available from speciality metal finishers.

Aluminium Bezel Polishing Procedure

1. 1Wet-sand the bezel with 400 grit wet/dry paper on a flat sanding block to remove surface oxidation and deep scratches. Use soapy water as lubricant.
2. 2Progress through 600, 800, and 1000 grit. At each stage, ensure all scratches from the previous grit are fully removed before advancing.
3. 3Buff with Mothers Mag & Aluminium Polish on a soft cotton cloth using circular motion. Follow with a clean cloth to remove residue.
4. 4For a factory satin finish (rather than mirror): finish at 1000 grit without final buffing, then apply a single coat of Flitz Metal Polish.
5. 5Protect with a single thin coat of Renaissance Wax — museum-grade microcrystalline wax that preserves polished metal without yellowing.

Collins Nameplate & Badge Restoration

The cast aluminium Collins logo badge is a significant cosmetic element. Original badges have painted recessed lettering (typically black or dark grey fill). Clean with mild dish soap and a soft brush only. Repaint letter recesses with a fine artist’s brush using model paint (Tamiya flat black XF-1 is ideal). Polish the raised surfaces only after the paint has fully cured.

Trim Strips

• The horizontal trim strips on the S-Line are extruded aluminium — treat identically to bezels
• Any trim strip with a tight bend that has cracked must be replaced — NOS trim is available through the CCA Support Directory and eBay
• Reproduction trim strips machined from 6061 aluminium are available from a small number of community suppliers — see Section 12
• Rubber gaskets and seals behind trim strips should be replaced if compressed or brittle — 1/16″ neoprene foam tape is an acceptable substitute

Dial Cover Restoration

The S-Line drum dial cover is optically clear acrylic or glass depending on production vintage. Acrylic covers: polish crazes and scratches with Novus Plastic Polish #1/#2/#3 system. Work from coarsest (3) to finest (1). Glass covers: use standard automotive glass polishing compound. Never use IPA or acetone on acrylic dials — chemical crazing is permanent.

Hardware — Screws & Fasteners

• Original Collins fasteners are typically machine-finished cadmium plated steel — do not replace with zinc-plated or stainless steel fasteners without noting this in your restoration documentation
• Cadmium-plated fasteners in good condition may be cleaned with a soft brass brush and light application of Flitz — do not use abrasive wheels
• Replacement cadmium-plated fasteners matching original specs (#6-32, #4-40, #8-32) are available from Mouser, Grainger, or Fastenal in small quantities
• Lightly coat all reinstalled fasteners with a thin film of NoOx-ID or lanolin-based corrosion inhibitor

1. 1Reinstall rubber feet and any bottom tray hardware first. Torque cabinet screws to finger-tight plus 1/4 turn — do not over-torque into painted holes.
2. 2Slide cabinet over chassis and align mounting holes before inserting any fasteners. The S-Line cabinet rear edge has a tight tolerance with the rear panel — ensure no paint build-up is preventing full seating.
3. 3Reconnect all front panel harnesses per your labelled documentation and photographs. Route wiring harnesses exactly as original — altered routing can cause interference or mechanical stress on connections.
4. 4Install bezels and trim strips before reinstalling knobs — bezel screws are harder to access with knobs in place.
5. 5Install knobs to original positions. Tighten set screws snugly — do not over-torque on the shaft flat. Verify all knobs turn freely without rubbing on the panel surface.
6. 6Install dial cover and nameplate badges last.

CCA Grade Self-Assessment

With reassembly complete, evaluate your restoration against CCA standards under natural daylight (not fluorescent or LED shop lighting, which flattens surface detail). Reference the grading table in Section 2. Be conservative in your self-assessment — the CCA community is experienced at identifying repainted sets, and honest disclosure of restoration work is required and respected.

• Photograph the completed restoration from all angles and in good lighting
• Document all work performed, products used, and dates — this record becomes part of the equipment’s provenance
• Label the inside of the cabinet with your callsign, date, and a brief description of work performed using a permanent marker on the chassis — a courteous practice for future owners

The following vendors are known to the Collins community as reliable sources for parts, materials, and speciality services relevant to S-Line cabinet restoration.

The following represent lessons learned from the Collins restoration community over many years — issues not covered in any service manual, but essential to achieving a high-grade result.