Tandon TM100-1
| Tandon TM100-1 | |
|---|---|
| Manufacturer | Tandon Corporation |
| Type | Full-height 5.25" floppy disk drive (single-sided, 48 TPI) |
| Interface | Shugart-style 34-pin |
| Compatible | IBM PC (5150) (early units), and a wide range of other OEM systems of the period |
| Model | TM100-1, TM100-1A |
| Storage | 250 KB unformatted; 160 KB (PC DOS 1.0, 8 sectors/track); 180 KB (PC DOS 2.0+, 9 sectors/track) |
| Media | 5.25" SS DD diskette, 48 TPI, 40 tracks |
The Tandon TM100-1 is a full-height 5.25-inch single-sided double-density floppy disk drive, supplied as the original drive in the first IBM PC (5150)s and sold widely as an OEM mechanism. It shares its chassis, servo board and mechanics with the double-sided Tandon TM100-2 and differs principally in having one read/write head instead of two; the two drives are visually near-identical and are covered by the same Tandon service manual.[1]
Specifications
[edit | edit source]All figures below are from Tandon's own service manual unless noted.[1]
| Parameter | TM100-1 |
|---|---|
| Form factor | 5.25-inch full height |
| Heads | 1 (single-sided) |
| Tracks per inch | 48 TPI |
| Tracks | 40 |
| Track spacing | 0.529 mm (20.8 mil) |
| Unformatted capacity | 250 KB per disk |
| Recording modes | FM, MFM, MMFM |
| Data transfer rate | 250,000 bit/s (double density) |
| Flux reversals per inch, inside track | 5,535 FRPI |
| Disk rotational speed | 300 RPM ± 1.5 % (295.5–304.5 RPM) |
| Instantaneous speed variation | ± 3 % |
| Average rotational latency | 100 ms |
| Motor start / stop time | 250 ms max / 150 ms max |
| Seek time, track to track | 5 ms |
| Head settling time | 15 ms |
| Average access time, including settling | 75 ms |
| Head life | 20,000 media contact hours |
| +12 V supply | +12 V ± 0.6 V, 900 mA average, 100 mV p-p ripple |
| +5 V supply | +5 V ± 0.25 V, 600 mA average, less than 100 mV p-p ripple |
| Hard (non-recoverable) error rate | 1 in 1012 bits |
| Seek error rate | 1 in 106 seeks |
| MTBF / MTTR | 8,000 hours at 25 % duty cycle / 30 minutes |
| Operating temperature | 10 °C to 46 °C |
| Operating humidity | 20 % to 80 % RH, non-condensing |
DC power arrives on a four-pin AMP connector J2: pin 1 +12 V, pin 2 +12 V return, pin 3 +5 V return, pin 4 +5 V. The chassis has a 3/16-inch quick-disconnect earth lug which Tandon requires to be connected to earth for correct operation.[1]
Configuration jumpers
[edit | edit source]The drive address and options are set by a programmable shunt at location 1E on the logic circuit board.[1]
- DS0 to DS3 — drive address. Normally all shunt jumpers are cut except the one drive-select jumper that addresses this drive.
- MX — multiplex. Used only in single-drive systems, to keep the drive logic enabled at all times. It must be cut in a multiple-drive system.
- HS, HM — not used; must be cut.
- W2 / W3 — write flip-flop control; W2 is the standard configuration.
- W4 / W5 — write protect control; W4 enables standard write protection.
- Terminator resistor pack RP1 — fitted in the last drive on the daisy chain only. Every other drive on the cable must have it removed.
The IBM machines that use these drives have a twist in the ribbon cable between the two drive connectors, so both drives are strapped identically and the twist selects which one the controller sees as A:. Tandon numbers its jumpers DS0 to DS3 and no manufacturer document consulted for this page states which one IBM used, so none is named here — check the shunt on the drive in front of you against Figure 3-3 of the service manual.
Maintenance
[edit | edit source]Head cleaning
[edit | edit source] | Tandon's service manual carries an explicit caution: "Do not use cotton swabs, solvents, or otherwise clean the head(s) by hand. Damage to the head(s) may result." The manufacturer's position is that good-quality media normally keeps the heads clean, and that where contamination is severe a cleaning diskette should be used according to its own maker's instructions.[1] |
Practice in the restoration community diverges from this where oxide from a shedding diskette has built up in a thick layer that a cleaning diskette cannot shift; minuszerodegrees.net describes using isopropyl alcohol on a cotton tip in that situation, taking great care, and notes it can take minutes of work to clear.[2] That is a deliberate departure from manufacturer guidance, taken as a last resort on a drive that is otherwise unusable. It is recorded here because people do it and should know what they are trading; it is not what Tandon says to do.
Lubrication
[edit | edit source]The head carriage rails are the usual problem: the original lubricant hardens over four decades and the carriage becomes stiff or stops moving. With the power off you should be able to slide the carriage along its rails by hand, feeling only the slight detent resistance of the stepper motor.[2]
Clean the old lubricant off the rails, then re-lubricate with a silicone grease.[2] Do not use white lithium grease: it is widely repeated as the right choice for these rails but no manufacturer document specifies it. Tandon's service manual contains no lubrication procedure at all, so there is no manufacturer figure to quote; silicone is the restoration-community consensus and is recorded here as such.
Belt
[edit | edit source]The rubber belt between the motor pulley and the spindle pulley stretches and perishes. Tandon's spare parts list gives the drive belt as part number 914000-001.[1] Replacements are made by several vintage parts suppliers; measure before ordering, as the aged original will have stretched.
Track 0 sensor
[edit | edit source]A dirty track 0 sensor produces symptoms that look like an alignment fault. Chuck(G), quoted on minuszerodegrees.net, notes that many apparent alignment problems on TM100 drives turn out to be a dirty track 0 sensor.[2] Check and clean it before touching anything adjustable.
Alignment and adjustment
[edit | edit source]Tandon's own tolerances, from Section 5 of the service manual.[1] All of these need a dual-channel oscilloscope, a certified alignment diskette (Tandon specifies Dysan 224/2A or equivalent) and a means of stepping the drive.
| Check | Tolerance | Adjustment |
|---|---|---|
| Drive motor speed | 300 RPM ± 1.5 % | R4 on the servo circuit board, with the 50 Hz or 60 Hz strobe ring on the spindle pulley stationary under mains-powered fluorescent light |
| Radial track alignment | Cat's eye pattern at Track 16: the smaller lobe not less than 75 % of the larger | Head module retaining and cam screws. Track 16 sits at a radius of 1.9167 inches from the hub centre; other tracks follow from 48 TPI |
| Index to data | 200 ± 100 µs at Track 1 | Index sensor retaining screw |
| Head azimuth | Within ± 18 minutes of arc, checked on the third burst at Track 34 | Not adjustable. If it fails, replace the head module assembly |
| Track 0 switch and stop | Per Section 5.9 and 5.10 | Switch position and stop |
The alignment diskette and the drive must be left to stabilise at room temperature for one hour before any check or adjustment.[1]
Disk compatibility
[edit | edit source]A TM100-1 reads single-sided 48 TPI 40-track disks written by any compatible drive. It cannot read the second side of a double-sided disk, having no second head, and it cannot read 96 TPI 80-track media. The IBM floppy adapter additionally requires soft-sectored diskettes.[2]
Related pages
[edit | edit source]- Tandon TM100-2 — the double-sided version
- IBM PC (5150)
- IBM FDD Adapter — the controller card
- Floppy Drive Repair
- Recommended Tools
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Tandon TM100-1 / TM100-2 48 TPI Operating and Service Manuals, Tandon Corporation, manual part number 179022-001 Rev. B, July 1983 — hosted on this wiki as File:Tandon TM100-1 TM100-2 48TPI Operating and Service Manuals 1983.pdf. Table 2-1 (electrical and operational specifications), Table 2-2 (reliability), Table 2-3 (environmental), Table 3-2 (DC power connector pin assignments), section 3.6 (drive address and option patching: DS0–DS3, MX, HS/HM, terminator resistor pack RP1), section 5 (maintenance checks and adjustments), section 6.1 and 6.2 (symptom diagnosis; head cleaning caution) and Appendix A (recommended spare parts list).
- ↑ 2.0 2.1 2.2 2.3 2.4 "Tandon TM100-2 in IBM 5150/5155/5160 — Known Problems/Issues", minuszerodegrees.net. Cited for: silicone-based lubricant (silicone grease or spray) for the head carriage rails; the use of isopropyl alcohol on a cotton tip for heavy oxide build-up, against the manufacturer's caution, and the observation that cleaning diskettes are abrasive; the spindle speed range 295.5–304.5 RPM and adjustment via R4 on the servo board; measuring speed with the 50 Hz / 60 Hz strobe rings on the spindle flywheel; the tantalum capacitors C36 and C43 (4.7 µF / 16 V) as first suspects when a TM100-2A overloads the host power supply; and Chuck(G)'s observation via VCFed that many apparent alignment faults on TM100 drives are a dirty track 0 sensor. This is a strong community reference for IBM PC hardware and is cited here as a secondary source.