• TU60 DECassette tape transport maintenance manual     (DEC-00-HTU60-C-D)
• TU60 DECassette tape transport engineering drawings    (Rev. C and Rev. D)

TU60   Tape   Transport   Unit Input Voltage     95 .. 130 VAC  47 - 63 Hz.  (TU60-AA) 190 .. 260 VAC  47 - 63 Hz.  (TU60-AB) Input Current 1.0 Amps Power dissipation 120 W. Operating temperature 50 to 105°F   (10 to 40°C) Dimensions 19" (width), 18¼" (depth), 5¼" (height) Weight 32 lb   (14,06 kg) During a write operation, 8-bit data bytes are parallel transferred from the interface to the TU60, phase encoded, and serially recorded on the tape. Except for the tape length, there is no maximum limit to the number of bytes that may be grouped into a data block. However, it is not possible to replace an individual block on a recorded tape. During a read operation, the self-clocking data bits are serially read from the tape, then parallel transferred to the interface at a peak transfer rate of 562 bytes per second.

TU60   Operational   Data Recording density 350 to 700 bits / inch Recording method Phase encoding Data transfer rate 562 bytes/sec (average) Format Variable block length (hardware formatted) Read / write speed 9,6 inch/sec Search speed 22 inch/sec Rewind speed 100 to 150 inch/sec Start / Stop time   < 20 ms read/write < 45 ms search (linear ramp control) Rewind time 30 sec (max), < 20 sec typical Bit error rate       » write errors       » read errors     1 in 108 1 in 108 (unrecoverable) 1 in 107 (recoverable, 3 rereads)

Each drive has identical and separate motor control and servo logic. However, formatting and read/write logic is common to both drives. It is therefore not possible to read or write from both drives simultaneously, but it is possible to perform a read or write operation on the selected drive and rewind the other drive concurrently.

Back to top

Do not attempt to use an audio cassette on the TU60 tape drives.

Since the tape in an audio cassette is not designed to tolerate the high drive tensions of the TU60, use of this type cassette will result in extremely rapid deterioration of the tape and subsequent failure of the drive due to excessive tape oxide deposits on the read/write head and tape guides.
The DEC cassette is relatively more expensive than an audio cassette. The lower "high frequency roll-off" of the digital tape also makes it a poor substitute for audio equipment. In addition, the coefficient of friction of the DEC cassette tape does not allow tape motion by capstan and pinch rollers.
In short, the TU60 DECassette Tape Transport and the DEC, 100% certified, Digital Cassette are designed to be used together.
 

TU60   Tape   Cassette Cassette type DEC, 100% certified, Digital Tape Cassette Tape width 0,150 inch   (0,381 cm) Tape thickness 1 mil, 0.30 mil oxide Tape life   Guaranteed > 1000 end-to-end forward passes Typically 2000-6000 end-to-end forward passes Capacity > 93 kbytes Storage temperature 40 to 122°F   (5 to 50°C)

The figure shows a typical TU60 data tape format.

Care of tape cassettes
Just as with diskettes, disks and other storage media there are some guide lines of use.

• Do not expose tape cassettes to excessive heat or dust.
  Most tape read errors are caused by dust or dirt on the read/write head. It is important to keep the tape clean.
• Always store the tape cassette in the plastic storage boxes when the tape is not in use.
  Keep empty boxes closed to guard against dust and dirt.
• Always rewind the tape to the BOT leader before you remove the cassette from the drive.
• Never touch the tape. Oil from fingers attract dust and dirt.
• Never use a contaminated tape cassette. This spreads dirt to the clean tape cassettes and could adversely affect tape transport reliability.
• Do not smoke near the tape transport or storage media. Smoke and ash are especially damaging to tapes.
• Do not put tape cassettes near lineprinters or other devices that produce paper dust.
• Do not put tape cassettes in any location where it may be affected by hot air.
• Do not store tape cassettes near electric motors or any other magnetic sources that may erase data.

Loading and unloading the DECassette
If you load a new cassette (or a cassette just shipped or accidentally dropped), load the cassette on a drive and perform a rewind operation. Then remove the cassette, turn it over, and perform an other rewind operation. This is done to pack the tape neatly in the cassette and also to place the full tape reel at the proper operating tension.
A cassette may be loaded on the drive with the drive locking bar either opened or closed. However, it is easier to load a cassette with the bar opened. Do the following steps to load a cassette.

1. Set the cassette write protect tab for the desired operation.
   The write protect tab is located on the cassette top right, when viewed with the label side up. To inhibit a write operation, fold this tab back to open the cassette recess. To allow a write operation, return the write protect tab to close the recess hole.
2. Hold the cassette with the thumb and index finger, and insert the cassette towards the left, at approximately a 45° angle, into the drive. Make sure that the cassette label faces outward and that the exposed cassette tape is to the left of the drive sprockets.
3. Apply a leftward pressure, while simultaneously rotating the cassette inward onto the drive sprockets. This action allows the cassette tape edge to slide under the lower door (lower door opens slightly) and bottom against the tape guides and read/write head.
4. When the cassette is properly loaded, the locking bar automatically closes over the cassette back edge and the lower door closes flush with the drive frame.
5. Press the manual REWIND pushbutton.
   The cassette is ready for read/write operations.

6. To unload the cassette, first, rewind the tape to the BOT leader.
7. To remove the cassette, gently push the locking bar to the right until it detents and withdraw the cassette from the drive.

Cleaning the TU60 DECassette Tape Drive
DIGITAL describes a preventive maintenance schedule in the maintenance manual which is based on a 4-hour use per day.
I do not think you run the unit that often as a hobbyist, but here are some useful tips.

• Clean the tape heads and guides using the appropriate head cleaner and a soft, lint-free cloth or cotton swab.
  Make sure that no parts still have head cleaner fluid when you use the drive. The fluid destroys the protective coating of the tape surface!
• Inspect the spindle assembly on each drive.
  Remove dirt, and if cleaning is needed on the rubber wheel, use a small brush and non-flammable cleaner.
• Check the fan filter and the fan. Clean if necessary.
• Run the MAINDEC diagnostic programs.
• Inspect the transport interior and exterior and clean if necessary.

more to be added soon ...

• Load a DECassette on each tape drive and momentarily press both REWIND pushbuttons.
  Make sure that the tape completely rewinds to the BOT clear leader (approximately 20 seconds).
• Momentarily press both REWIND pushbuttons again and check that the tape drives rewind the tape for approximately 1 second.
• Run the appropriate diagnostic tests to make sure that the tape drives operate correctly.

Address Instruction 000200 013737 000202 177570 000204 177500 000206 000137 000210 000200

You can toggle in the small program on the left side. The program starts at address 000200, and reads the switch setting of the Switch Register to set the tape motion. The switch settings are listed in the table at the right.

Operation Drive A Drive B Read 000005 000405 Space Back Block 000011 000411 Space Forward Block 000015 000415 Write 000003 000403 Rewind 000017 000417

The MAINDEC diagnostic programs use the following Switch Register settings.

    SW 15=1   (100000)   halt on error
    SW 14=1   (040000)   loop on test
    SW 13=1   (020000)   inhibit error reports
    SW 10=1   (002000)   ring bell on error
    SW 09=1   (001000)   loop on error
    SW 08=1   (000400)   do not change drive
    SW 07=1   (000200)   pause 200 ms