Test Vacuum Source
By Les Smith
Hello, all and welcome to Brett Mohr. Regarding the question of a good test vacuum source, I know that this isn't exactly what you meant, but one of the best is your mouth. Let me explain. The teat of a properly rebuilt air motor is as follows. Holding the air motor in your hands in an upright position, you should be able to draw with your mouth on the nipple, or a length of hose connected to the nipple, and the air motor should turn smoothly and freely, with no binding or hesitation whatsoever. Assuming that the air motor passes this test, next install it in the player action and connect it to the transmission. If you have done a good job of disassembling and cleaning the transmission and restoring the transmission and spoolbox, you should now be able to draw on a length of hose connected to the air motor and have BOTH the air motor and trans- mission turn smoothly and without hesitation, in both play and reroll positions, with the only source of suction being your mouth! Further, you should now be able to place a roll in the spoolbox and have it turn smoothly as well. If your air motor and transmission cannot pass these tests you HAVE PROBLEMS that require attention. Now turn your attention to the stack.
If you have done a first-class job of restoring the stack, valves, pouches, gaskets, etc., you should be able to attach a length of tubing to the main suction supply nipple to the stack, draw on it vigorously with your mouth, AND IMMEDIATELY FEEL ALL THE VALVES SEAT AND HOLD VACUUM! This test will work on most player stacks, with either horizontal or vertical valve setups and even on early double valve systems like Standard. It won't work on Amphion valve systems that use those TERRIBLE upside down valve blocks. If you can't get the valves to seat, when drawing on the ENTIRE stack by mouth alone, you have problems and the player is probably not going to work well with the foot pumps alone, at which point many technicians embrace the idea of an electric suction box!
Lastly, if you have done a really fine, 100 point restoration of the stack and air motor, your rebuilt player should be able to pass this final test. Take the hose from your air motor and Y it into a hose going to the stack with a T fitting. Attach another length of hose to the 3rd side of the T fitting. Now put a roll in the spoolbox and the transmission into "play". YOU SHOULD NOW DRAW VIGOROUSLY ON THE FREE HOSE GOING TO THE T FITTING AND THE AIR MOTOR, TRANSMISSION AND ROLL SHOULD TURN, THE VALVES IN THE STACK SHOULD SEAT AND HOLD VACUUM AND THE FIRST COUPLE OF NOTES ON THE ROLL SHOULD PLAY!!!!!!!! All this and the only source of suction is your mouth!
When the day comes that you can rebuild a player that will pass ALL of the above tests, you can take pride on a job well done. This isn't some- thing you learn in a year, or two or three, but it is a goal towards which to strive. For now, just try to do the best job that you can. If you do so, eventually the day may come when the only test vacuum source you need is your mouth. In the meantime, welcome to the group and above all, HAVE FUN!
Les Smith
lessmith@buffnet.net |
(Message sent Tue 16 Jan 1996, 07:28:33 GMT, from time zone GMT-0500.) |
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