Drive Belt Replacement
Drive belt replacement is the repair for the rubber belts that turn the disc in belt-driven floppy drives and the flywheels, capstans and counters in cassette recorders and datasettes. Old belts stretch and slip, or perish completely; DataServe Retro, which services Spectrum +3 drives, finds that an unmaintained drive usually has a perished belt, and that a broken belt often leaves a sticky black residue round the motor capstan.[1] The work is the same on any belt-driven mechanism: remove the old belt and every trace of it, fit a belt of the right size and section without twisting it, and check the speed. For the belts and speed settings of particular floppy drives, see Floppy Drive Repair.
When to use it
[edit | edit source]- A floppy drive's motor runs but the drive will not read. On the Spectrum +3, Spectrum for Everyone calls the belt the weak point of the 3-inch drive, because it deteriorates with age.[2] The Floppy Drive Repair page lists which common drives are belt-driven and which are direct-drive.
- A cassette deck's playback speed wanders, or it struggles to fast-forward or rewind. Spectrum for Everyone's advice for the +2 Datacorder is then to change the belts.[3] Atari's 410 service manual checks the belts for stretch, and its maintenance table notes that the counter belt fails most often.[4]
- A belt is visibly slack, cracked or sticky, or has gone altogether.[1]
Safety
[edit | edit source]- Unplug the machine before opening it. Some cassette recorders carry mains inside: the Atari 410 has its mains supply inside the case on every version except the 410 P.[5]
- Let the capstan dry after cleaning it with fluid; DataServe allows a couple of minutes before fitting the new belt.[1]
Tools and materials
[edit | edit source]- Tweezers to lift belts out and route new ones.[1][2]
- Cotton buds and isopropyl alcohol or head-cleaning fluid.[1][2]
- A small flat-bladed screwdriver for scraping dried pieces of belt off pulleys.[1]
- A ruler or calipers for measuring the old belt.[6][7]
- The correct replacement belt.[1]
| Machine | Belt | Size | Source |
|---|---|---|---|
| Sinclair ZX Spectrum +3 (3-inch drive) | Drive belt | Flat, 71.0 mm internal diameter, 2.8 mm wide, 0.6 mm thick (CPC AVBELT5) | Spectrum for Everyone, CPC[2][8] |
| Sinclair ZX Spectrum +2 (grey) Datacorder | Main belt (also the black +2A) and smaller clutch belt | Main: square section, 70 mm internal diameter, 1.2 mm section (CPC AVBELT107) | Spectrum for Everyone, CPC[3][9] |
| Atari 1010 (Chelco 1010C) | Counter belt FC100251 | 65 × 1 × 1 | Atari field service manual[10] |
Procedure
[edit | edit source]Identify the replacement
[edit | edit source]- Use the maker's part number or size where the service manual gives one. Floppy Drive Repair lists the belt part numbers for several drives, and the table above gives sizes for some other machines.
- Otherwise measure the old belt. DataServe Retro, which sells belts, says to lay the old belt out in as perfect a circle as possible and measure its internal diameter, and for a flat belt to measure the width and, if possible, the thickness.[6]
- Match the section as well as the size. Belts are sold as flat section, given as internal diameter by width by thickness, and as square section, given as internal diameter by section.[8][9][6]
- Allow for stretch. An old belt has stretched, so a moderator on the Audiokarma forums subtracts 10 to 15% from the measured size and picks the nearest belt.[7] Do not go further than that: DataServe has had drives returned with belts that were too small, or with a tight elastic band, and their motor bearings were ruined by the extra tension.[1]
Remove the old belt
[edit | edit source]- Unplug the machine and open it as its own guide describes.[5]
- Lift the old belt off with tweezers. If it has broken, pick out every piece, including any inside the mechanism and any stuck to the pulleys.[1][2]
- Scrape stubborn dried pieces off carefully with a small flat-bladed screwdriver.[1]
- Remove sticky residue from the capstan with a few drops of head-cleaning fluid or isopropyl alcohol on a cotton bud, turning the capstan as you rub, until it is clean. Residue left behind makes the new belt slip, ride off the pulley or age quickly.[1][2]
Fit the new belt
[edit | edit source]
- Route the new belt with tweezers. On the Spectrum +3 drive it goes round the large pulley first and is then stretched over the small motor capstan.[2]
- On a mechanism with two belts, follow the order its guide gives; on the grey +2 Datacorder the smaller, lower belt goes on first.[3]
- Check that the belt sits straight on every pulley and is not twisted.[1][2][3]
Checking the repair
[edit | edit source]- Check that the belt sits snugly and straight on the capstan and pulley. Leftover residue makes a new belt ride up and slip off.[1]
- On a floppy drive, check the spindle speed with the method its manual gives; Floppy Drive Repair has the figures and procedures for several drives.
- On a cassette deck, play a tape and listen for steady pitch. If the speed still varies with new belts, look for something else dragging on the flywheel, as with the grey +2's pause latch.[3]
Common mistakes
[edit | edit source]- Fitting a belt that is too small, or an elastic band, which overloads the motor bearings.[1]
- Leaving pieces of old belt or residue on the capstan or pulley.[1]
- Fitting a belt twisted.[1][3]
- Fitting a flat belt where a square one belongs, or the reverse.[8][6]
- Replacing the belt without cleaning the rest of the mechanism while it is open. DataServe finds that a neglected +3 drive usually also has a dirty head and dried-out grease on the worm drive.[1]
Worked examples on this wiki
[edit | edit source]- Sinclair ZX Spectrum +3 Disk Drive Belt Replacement: the 3-inch drive's belt, the residue it leaves, and servicing the head and worm drive at the same time.
- Sinclair ZX Spectrum +2 Datacorder Belt Replacement: a twin-belt cassette mechanism and the pause-latch fault that mimics a worn belt.
- Atari 1010 Maintenance Guide: drive and counter belts on both versions of the recorder.
- Atari 410 Maintenance Guide: the four belts of the revised 410.
- Panasonic Q General Maintenance: a perished DVD tray belt.
- Floppy Drive Repair: which drives are belt-driven, their belt part numbers and their speed settings.
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 DataServe Retro, "Servicing the Sinclair ZX Spectrum +3 Disk Drive" (retrieved 2026-10-25): a perished belt, a dirty head and dried worm-drive grease as the usual faults of an unmaintained drive; tweezers, cotton buds, head-cleaning fluid and the correct belt; removing every piece of old belt from the drive, the capstan and the large pulley, scraping stubborn pieces off with a small flat-bladed screwdriver; pieces left behind make the new belt ride up and slip off; the sticky black residue round the capstan makes a new belt slip and age quickly, and is removed with head-cleaning fluid on a cotton bud while turning the capstan, which is then left a couple of minutes to dry; the new belt goes over the large pulley first and is stretched over the capstan; the belt must sit straight on capstan and pulley and not be twisted; belts that were too small, and even a tight elastic band, ruined the bearings of drives sent in for repair.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Spectrum for Everyone, "Replacing the drive belt on your +3 FDD", February 2017 (retrieved 2026-10-25): the belt as the weak point of the +3's drive because it deteriorates with age; the old belt removed with tweezers, usually in pieces; the motor pulley cleaned of rubber residue with isopropyl alcohol and a cotton bud; the new belt routed round the large pulley first and then the motor pulley; checking that it is not twisted or misaligned.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Spectrum for Everyone, "Servicing your +2's Datacorder", February 2017 (retrieved 2026-10-25): steady playback calls only for cleaning the head, capstan and pinch roller with isopropyl alcohol; playback speed that varies significantly, or difficulty fast-forwarding or rewinding, calls for new belts; the mechanism comes from cheap mono tape decks; belts removed with tweezers and the new ones fitted without twisting, the smaller (lower) belt first on the grey +2's twin-belt mechanism; if the speed still varies, the flywheel may be fouling the pause latch.
- ↑ Atari, Inc., 410 Program Cassette Recorder Field Service Manual, FD100004, May 1982, maintenance (pp. 1-1 and 1-2). Hosted as File:Atari 410 Program Cassette Recorder Field Service Manual FD100004.pdf; see Atari 410 Maintenance Guide.
- ↑ 5.0 5.1 Michael D. Current (ed.), Atari 8-Bit Computers: Frequently Asked Questions, sections 3.1 and 6.7, faqs.org. See Atari 410 Maintenance Guide.
- ↑ 6.0 6.1 6.2 6.3 DataServe Retro, "Cassette Recorder / Disk Drive Belt FLAT Section 81mm X 3.5mm x 0.6mm", product page (retrieved 2026-10-25): to find the size needed, lay the old belt out in as perfect a circle as possible and measure the internal diameter, and for flat-section belts also the width and, if possible, the thickness.
- ↑ 7.0 7.1 "Cassette belt", thread 246325, Audiokarma forums, reply of 13 March 2023 (retrieved 2026-10-25): measure the old belt, subtract 10 to 15% and choose the nearest size; use a digital caliper for thickness and width; the service manual's part number can sometimes lead to the belt size. Community advice.
- ↑ 8.0 8.1 8.2 CPC (Farnell), "Flat Section Drive Belt 71.0 x 2.8 x 0.6mm Rubber", order code AVBELT5 (retrieved 2026-10-25): internal diameter 71 mm, width 2.8 mm, thickness 0.6 mm, rubber; listed under "Belts - Flat Section".
- ↑ 9.0 9.1 CPC (Farnell), "Square Section Drive Belt - 70x1.2mm (Dia.xW)", order code AVBELT107 (retrieved 2026-10-25): internal diameter 70 mm, 1.2 mm section, rubber; listed under "Belts - Square Section".
- ↑ Atari, Inc., 1010 Cassette Recorder Field Service Manual, FD100223 Rev. 02, September 1983, belt replacement (pp. 3-10 to 3-12) and parts lists (pp. 6-1 and 6-2). Hosted as File:Atari 1010 Cassette Recorder Field Service Manual FD100223 Rev 02.pdf; see Atari 1010 Maintenance Guide.