Replacing belts on a Tascam 234 Guy Burns April 2012

Introduction The Tascam 234 has two drive belts that can stretch and/or disintegrate as they age: the capstan belt which drives the cassette, and the cam belt which moves the transport mechanism. These belts are difficult and time-consuming to replace. Allow 4-5 hours for replacement. Belt Details Capstan belt: The capstan belt, a flat-section belt, had lost its stretch on my Tascam 234 and was unable to drive a cassette. The belt had only just enough stretch to stay in place. Although unable to Original capstan belt which had lost its stretch, though it still remained in place. drive a cassette, the belt was a good indicator of the length of the belt path. It measured 117 mm in length when flattened, indicating the path length was 234 mm (2 x 117 mm). In terms of a circle, the diameter of the circle formed by the belt was just under 75mm. To allow for stretching, I chose a slightly smaller belt with these dimensions: • diameter – 69 mm • width – 5 mm

Cam Belt: The cam belt, a squaresection belt, was okay but I replaced it anyway. The original (and replacement) had these dimensions:

• square section – 1.4 mm

Instructions Before dismantling, it is a good idea to have a dozen or so small plastic tubs in which to deposit screws that go together, and a piece of paper with the step number (use the numbers in these notes). The tubs can be stacked on top of one another to allow for easy re-assembly (they will be in order). Locations are from the front of the Tascam 234 when it is upright. e.g. left means the power switch side. Screws, when specifically referred to, will be indicated by a red arrow in the associated image.

Small tubs, stacked on top of each other, holding screws as they are removed, and notes.

1. Undo the five screws that hold on the outer case: two on the left, two on the right, and one in the top centre.

• thickness – 0.6 mm

• diameter – 57 mm

Where to Buy I purchased both belts from a local supplier, Leading Edge Electronics (03 6424 8322), in Devonport, Tasmania. The cam belt was in stock and cost $3. The capstan belt, $7.95, had to be ordered and arrived in a few days from WES Components in a plastic bag labelled “DAI-1CHI, 69 x 0.6 x 5, Japan”, the numbers indicating the belt size. Ebay is another source of belts specifically for the Tascam 234. And you could try Electronix.com which sells belts for a few dollars each. Their method of measuring a belt is described here: http://www.electronix.com/ beltinstall.html.

Original cam belt which was still okay. The belt circumference was slightly less than 180 mm. The inside diameter when laid out as a circle was 57mm.

2. Remove the white and the black multipin connectors located to the right of the transport mechanism. Step 2: White and black multipin connectors.

3. Remove the white and the red multipin connectors, marked P106 and P101, located in the centre top area.

6. Remove the four screws underneath the 234 which hold the transport unit in place.

Step 6: the four screws holding the transport unit in place.

4. Remove the three multipin connectors, two white and a red, at the left of the unit behind the power switch.

5. Remove the two screws on top of the 234 near the white foam strips which hold the transport unit in place. Then while the 234 is still upright (it is turned upside down in the next step), remove the cassette bay door by opening the door and gently pulling it upwards at a 45º angle while rocking side to side.

7. Remove the base plate and its six screws (under the right side of the Tascam 234).

Step 7: the six screws that allow one of the base plates to be removed.

8. Loosen, but do not fully remove, the two screws underneath the Tascam 234 that hold the transport control panel in place. The two screws do not have to be fully removed because the transport control panel has mounts that slide in under the heads.



Remove the transport control panel from the Tascam 234 by first sliding the bottom mounts from under the two screws previously loosened. Carefully remove the three multipin cables disconnected in step 4. These pass through holes at the bottom of the transport unit. If this proves difficult, remove the cables after the transport unit has been removed in step 13. When replacing the transport control panel, the transport unit has to be moved out of the way slightly to allow the transport control panel to be inserted at the top first, otherwise it won’t slip into place.

9. Remove the 2-pin red connector (one mauve, one white/ yellow wire) on the front right of the large main circuit board.

Step 8: one of the two screws that hold the transport control panel in place.

10. Remove the five multipin connectors on the underside of the Tascam 234. Even though they can’t be mixed up, it is a good idea to number them 1-5 from left to right to distinguish them from other connectors when reassembling.

11. Remove all knobs from the front fascia: Step 8: the transport control panel removed from the Tascam 234 showing the cables still connected.

• Input knobs (orange) • Headphone knob (green) • Pitch control (white) • Output (white) • Pan (gray)

Remove the three screws underneath holding the fascia in place; and on top, remove the two outside screws.

Step 11: one of the three screws underneath that hold the fascia in place.

12. Remove the single screw that holds the power switch in place. The power switch is not connected to the transport unit (the next to be removed), but by removing this screw the power switch can be moved out of the way making it easier to remove the transport unit.

13. Remove the single screw underneath that holds the speed controller in place. Then remove the transport unit by angling and jiggling.

14. Remove the two screws holding the transport unit circuit board in place.



Then remove the circuit board by lining up the pivots with the holes in the mounting plate.

Step 14: Ready for belt replacement: the transport unit with its circuit board laid out.

15. Remove the three screws holding the mounting plate which contains the cam belt motor.

16. The mounting plate which contains the transport belt is held in by three screws, one of which has already been removed in step 15. Remove the other two screws and then replace the capstan belt. It is quite fiddly and may take 10-15 minutes. See photos over page. Step 15: Two of the screws that need to be removed to replace the cam belt.

Step 16. Above: one of the two screws that need to be removed to replace the capstan belt. Below: the screw (already removed, under the orange cable) that holds in place the capstanbelt mounting plate (the main plate visible), and the cam-belt mounting plate (on the far right).

Replace the cam belt (shown looped around the small pulley, photo left), by lifting the motor out of the way. Note that by doing so, the white cam disengages from the black radial arm on the large black plastic gear. The cam must be re-engaged during reassembly otherwise the transport won’t work properly.

Another view of the white cam engaged with the black radial arm.

During the manipulations necessary to replace the capstan belt, a small white piston may fall out of the black cylinder shown in the photo, right. It is easy to replace the piston: the metal clip that looks a bit like a paper clip goes through a hole at the bottom of the piston, and then the piston is inserted into the black cyclinder, rubber-grommet end first.

Above: A close up of the capstan flywheel, and behind it, the pulley that drives the flywheel. The capstan belt goes around both.

Above: The transport unit showing the capstan flywheel on the left and its motor and driving pulley behind. On the right is the cam-belt motor with a white cam and large black gear underneath.

References: http://www.thegreatbear.net/audio-transfer/tascam-234-4-track-cassette-capstan-belt-replacement/