Handpiece Control Block (Model #49-87) PRINCIPLE OF OPERATION: The handpiece control block has drilled passages for drive air, coolant air, collant water, and gauge pressure. Sandwiched between the two halves of the block is the “hold back” diaphragm. When a handpiece is in its holder or the holder is otherwise locked out, signal air passes through the holder valve and applies pressure to the diaphragm which in turn closes off the passages to that handpiece. When the handpiece is lifted from its holder the valve closes, shutting off and exhausting the signal air. This permits the diaphragm to deflect away from the passages allowing air and water to supply the appropriate handpiece. Drive Air Adjustment Stem Hold Back Air In Water or Water Signal Out To Gauge Turbine Air In Drive Air to Handpiece Coolant Water In or Water Signal In Coolant Air In The above control blocks are designed to provide automatic control of 2 to 5 handpieces when used with similar hold back air valve. The pilot valve used must supply positive air pressure (80 p.s.i.) when the handpiece is in the hanger. The supply in and gauge pressure out ports are located on the end. The handpiece ports are on the side. Each handpiece position is grouped, as indicated by the installed barbs in the above image. The #48-87 can be used for 2 or 3 handpieces. Port layout is the same for all models. Unused handpiece positions must be blocked off via use of 10/32 hex plug and nylong washer. After installation all air must be purged from the water system. If a position of the block is not used, loosen the hex plug on the water out port for that position and step on the foot control. Allow water to flow through any unused ports then replace the plug. 7310 Oxford Street • St. Louis Park, MN • 55426 Phone (800) 331-7993 • Fax (888) 729-1016 www.amerdental.com SYMPTOM POSSIBLE CAUSE TROUBLESHOOTING GUIDE TEST PROCEDURE IF TEST NORMAL IF ABNORMAL Water or air leak from block. Loose or defective diaphragm. Soap block and check for air leak. If leak stops, no Tighten loose fittings. Loosen all further action screws in center of block first, and then required. tighten screws around the edges. If leak continues from diaphragm, replace. Also, check inner surfaces for defects in the sealing surface. All handpieces run at once. Unit has low air pressure. Check for 80 psi at guage. Adjust to 80 psi and recheck handpieces. Diaphragm defective. Open block. Check diaphragm for deterioration. Replace diaphragm. One handpiece will not shut off. Holder valve not operating. Remove tubing from holder valve Replace diaphragm. where it attaches to the block control block. Check for air flow when handpiece is in holder or when valve is depressed. Check holder valve for operation. Adjust valve position in holder. Replace if necessary. One handpiece will not operate. Holder valve not operating. Make sure holder toggle is down. Remove output tubing from holder valve. Air should stop when valve finger is forward. No further action required. Repair sticking valve or holder. Replace if necessary. Water drips continuously from handpiece when foot control is at rest or is slow in stopping when foot control is released or water sprays momentarily when handpiece is first picked up. Foot control not shutting off completely or not exhausting. Disconnect signal air line to coolant water toggle. Check for air flow when foot control is at rest or slow air flow after foot control is released. It should stop within one or two seconds. Go to next step. Clean foot control poppet for sticking or replace valve o-rings. See foot control section for instructions. Water relay or water relay needle valve not closing. After determining there is no air signal to relay, remove output water line relay. There should be no flow. Water sprays from an unused handpiece when another is being used. For units with purge system only. Purge toggle switch is leaking. With the same line disconnected there should be no flow from the purge valve. Cross over through control block diaphragm. Remove the water tubing on the control block to the unused handpiece. There should be no water flow when another handpiece is used. No water coolant Flow control valve is Open flow control fully while running to handpiece closed or water toggle handpiece. switch is off. If unit has a water coolant , switch on foot control, it should be on. No air signal to water relay or water relay needle valve. For units No air signal through equipped with foot control switch. an optional water coolant switch on the foot control only. No further action required. Replace water relay. Next step. Disassemble purge toggle. Check for debris or worn o-rings. Clean, lubricate, or replace as necessary. Replace the diaphragm. If water begins to flow, adjust to desired flow. Next step. Disconnect air signal line to relay. When foot control is depressed, there should be air flow. If air signal is present as well as water, replace water relay. Check for pinched or clogged air supply between foot control and relay. Remove output tubing from coolant switch. Depress foot control. Check as above. Repair or replace coolant switch. See foot control section for breakdown.
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