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Adjusting the Amphion Tracking System

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Adjusting the Amphion Tracking System

The Amphion tracking mechanism is what's called a 'bleeding' tracker. That's because an equal level of vacuum is applied to both bellows and they will only move when one of the two tracking valves opens a tiny bit and atmosphere is allowed to bleed into a bellows -disrupting the balance. Information about how the tracking system operates is found in the Amphion Service Manual but it is also available below -click here.

Since the operating vacuum for the mechanism comes from the stack, the tracker only works in the Play mode. Also, since there is no vacuum applied to the mechanism when the system is in the Reroll mode, the pressure inside the tracking bellows is equal and they should automatically center. For this reason, it is important that the tracking bellows and the music roll be properly centered when the system is at rest (no vacuum applied).

If you have a system that's identical to the one in the picture, there are a few things I can say that might help solve your tracking problem during Reroll.

First, before putting a roll into the spoolbox, check the condition of the Tracking Valves. Disconnect the hoses that go from the valves to the bellows where they connect to the bellows assembly and suck on each one. There should be no air leakage. If there is, the leather might need to be changed or the nipple that the leather closes might need to be resurfaced.

Second, the tracking bellows in the picture might not be properly positioned. When the system is at rest (no vacuum applied) and a music roll is in place, the moveable center board in the bellows assembly should be dead in the middle; just like it is in the diagram. If it is not, use the Centering Adjustment to center the moveable board. Also, disconnect all three tubes at the tracker and block off the ones marked A and B in the diagram. Then connect a tube to C and suck on that tube. If the bellows are in good shape, the moveable center board should be in the center and you shouldn't feel any air leakage. If there is leakage or if the center board does not center, the bellows cloth should be replaced. Also, the bellows cloth should be very supple because it has to react to very slight changes in vacuum pressure.

Third, when a music roll that's in excellent condition (with paper that is exactly 11-1/4" wide) is in the spoolbox and connected to the Take-Up spool, both of the Tracking Valves should be closed. Here again, check to see if they're sealing well by sucking on the tube that goes between the valve and the tracking bellow. If they're not, changing the leather on the valve might solve the problem. (Use standard valve leather.) Also, the holes in the trackerbar should be properly aligned with the holes in the music roll such that the holes in the roll open the holes in the trackerbar 100%. If they don't, the system is not correctly centered. (See NOTE below.)

NOTE: Changing the leather may necessitate adjusting the Tracking Fingers. Most technicians believe that the fingers should be adjusted so that there is little-to-no clearance between the tracking fingers and the edges of a roll that is exactly 11-1/4" wide. When the roll is perfectly centered over the holes in the trackerbar, and the center board in the bellows assembly is dead center, both valves should be closed. And, the slightest movement of the roll to the right or left should open the corresponding valve -which will cause the one of the bellows to move in the direction to oppose that movement and return the roll to center.

If the tracking fingers do not operate as explained above, the fingers must be bent slightly. In the above picture, you can see that the finger on the left is slightly bent. It is most likely that it was bent at the factory. Another fairly common problem with this tracking system has to do with the nipple that opens and closes as the finger moves. Due to acids in the leather, the brass nipple can become corroded, which prevents the valve from seating well. Generally, a very light sanding or filing will remove the corrosion, but it's also advised to change the leather if the end of the nipple is resurfaced.

Hope this helps.


    The correct registration of tracker ports with their corresponding perforations of the music roll is another detail essential to the perfect operation of the player.

    The Amphion automatic tracking apparatus shifts the music roll and thus moves the sheet longitudinally across the tracker bar instead of shifting the bar itself as is frequently done.

    Referring to Figure 7 (diagram above) the roll adjusting pneumatic is seen at the left of the spool box. This is a double pneumatic with a movable center board attached to the roll adjuster rod. Each side or section of this pneumatic is connected through small internal orifices to a single vacuum supply tube, which is connected to one of the decks of the action.

    Also each side of the pneumatic is also connected to one of the roll adjuster (or tracking) valves, which are mounted above the tracker bar near its ends with their wires overhanging the bar on the right and left edges of the music sheet. These valves are normally closed when the music sheet is in its proper position. Under such conditions, both sides of the double pneumatic are subjected to the same (vacuum) tension, which holds its center board in a fixed position and centralizes the music sheet over the bar.

    With the sheet in motion, a movement of it lengthwise of the bar causes the edge of the sheet to make contact with the valve wire toward which the motion occurs. This opens the valve and allows air to enter that side of the double pneumatic to which the valve is connected, rendering that side of the pneumatic inoperative. The opposite side of the pneumatic is thus allowed to collapse. This moves the music roll back into proper position over the bar. If the automatic tracking apparatus fails to function properly, the cause will usually be found to be a leak in the rubber cloth cover of the pneumatic or in its valve or supply connections.

    Occasionally it may be necessary to adjust the roll adjuster valves, and this is readily done by simply bending the valve wires with the fingers. When the sheet is in proper registry with the bar the weights at the rear of these valve wires should seal the tubes with which they make contact and the wires should just clear the edges of the sheet.

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While it is quite unlikely that the holes in the music roll won't align properly with the holes in the trackerbar when all of the items mentioned above are working and adjusted correctly, it 'is' possible. That's because the basic centering of the system is determined by the physical location of the bellows assembly. If for some reason the assembly is in the wrong physical position or if the metal rod on the top of the assembly is bent, the rod can be bent as necessary to correct the problem.

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This page was created on January 5, 2017 and last revised
on August 23, 2018 by John A. Tuttle, who Assumes No Liability
For The Accuracy or Validity of the Statements and/or Opinions
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