User manual ENSONIQ EPS PERFORMANCE SAMPLER

[. . . ] , To Transformer- 4 Back of Unit 4 Heat Sink 4. 0 Amp, 250 V 4. 0 Amp, 250 V 1. 5 Amp, 250 V 1. 5 Amp, 250 V Jl 1. 5Amp. 250V To Main Harness Heat Sink 1 . PROBLEM: Hum or buzz in audio output; EPS PERFORMANCE SAMPLER PERFORMANCE SAMPLER crashes randomly; or problems develop after inserting a memory expander. SOLUTION: Check the voltages on the power supply at J4 with the power supply loaded (main board and display board connected). Using pin 11 as ground, the voltages on pins 14, 16, and 16 (of J4) should be +4. 75 to +5. 25 VDC. [. . . ] If a clip breaks due to tco much pressure, contact ENSONlQ Customer Service for a replacement key. While lifting up on the back of the key (near the spring hole) push the top of the screwdriver toward the back of the keyboard to release the clip. C. Solder the connector leads together 1) Hardwire the connector leads together (horizontally). If there are two rows of leads on each board. The twenty-pin dual-row connector is a better co~ector and does not need to be hardwised. They go on where there are single keystops. Place the front of the key on fast, then press the back of the kejj down zm!i!Make sure that the clip for each key is engaged. To reinstall the springs, place the spring into its hole on the key (open side up). Insert the small/thin Phillips screwdriver into the spring and push down and out to expand it. Then move the bottom the spring into the keyboard frame. Making note of the proper polarity, connect the keyboard ribbon cable to the main board. While investigating Keyboard Calibration errors, it was found that a break in the interconnection of the two coil boards can cause a variety of problems. The coil board connectors move in a horizontal plane while the force exerted on the connector by playing is in a vertical direction. If one pin doesn't make contact or loses contact briefly, the keyboard might not calibrate, might freeze up (button presses have no effect), show an ERROR 144, or might start playing random notes. Hardwiring the two boards together forms an absolute connection. The tin connectors (most commonly used coating/material for connectors) builds up some oxide over time. This oxide is cleared by a wiping action when the pins are moved in their plane (here it would be horizontally). However, the force on the coil board-to-coil board connector is vertical ONLY (no movement horizontally at all) and therefore the oxide would not be cleared off. This oxide buildup could cause one or more pins to lose contact over time. This problem was masked by the type of flux that we use (Service Bulletin #9B). This flux does leave some residue and we now clean all connectors that hang over the edge of the board (for example the Keypad/Display connector) or hand solder them into the board Cleaning the connectors helped temporarily because the wiping action of separating the coil boards and then reconnecting them broke through the oxide buildup on the connector. This oxide buildup problem was very difficult to find, because shipping a unit from a customer to the factory could cause the coil board-to-coil board connector to shift enough to break through the. [. . . ] Remove the white keys first then the black keys. We suggest keeping the keys in order to make them easier to put back on. Service Bulletin #I2 page 5 With the middle D through G keys removed from the center of the keyboard: B C Figure 5 - 12-pin coil board-to-coil board connector C F. Solder the Connector Leads Together Using the jumper wires provided, hardwire the connector leads together (horizontally). If there are two rows of leads on each board, do not solder them together If the connector is a twenty-pin dual-row, contact ENSONIQ Customer Service for a replacement keyboard. G. [. . . ]