User manual YORKVILLE AP4040 V2

[. . . ] Le point d'exclamation à l'intérieur d'un triangle équilatéral est prévu pour alerter l'utilisateur de la présence d'instructions importantes dans la littérature accompagnant l'appareil en ce qui concerne l'opération et la maintenance de cet appareil. S2125A FOLLOW ALL INSTRUCTIONS Instructions pertaining to a risk of fire, electric shock, or injury to a person CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER (OR BACK). REFER SERVICING TO QUALIFIED SERVICE PERSONNEL. Read Instructions: The Owner's Manual should be read and understood before operation of your unit. Please, save these instructions for future reference and heed all warnings. Packaging: Keep the box and packaging materials, in case the unit needs to be returned for service. [. . . ] The lower the voltage from collector to emitter, the lower the device dissipation. During quiescent conditions, there is 55VDC on the collectors of output transistors Q14 and Q22. The peak AC voltage that can appear on the amplifier's output is approximately 139V peak. How can an output transistor deliver a 139V peak when its collector is only at 78VDC?It can if its collector is pulled up to 144VDC as the output signal's peak rises above 78VDC. The second tier voltage must remain above the amplifier's output voltage by amount Vm. Therefore the circuitry controlling the second tier voltage must increase the tier voltage before the amplifier's output voltage reaches 78VDC. This leading voltage is necessary to compensate for time lag of the second tier circuit during fast rising amplifier output signals. The voltage between the amplifier's output and test point 4 is approximately 12VDC derived from the voltage drop across ZD4. We call this voltage the "floating battery" because it floats on top of the output audio signal with test point 4 always being 12VDC greater than the peak of the output signal. Test point 4 drives the gate of mos-fet Q11. Q11 controls the transistors of the upper tier. The third operation that the relay provides is "overheat shutdown". If for some reason the fan cannot keep the heatsinks in a safe operating temperature area then the fan control circuit (on board M1147) will deliver through D207 a positive current to turn Q203 on and turn Q201 off to turn off the relay and disable the voltage amplifiers. When the fan has cooled down the temperature of the amplifier, then the signal through D207 will disappear and the relay circuit will turn on the relay to resume normal operation. Anytime the relay is in the "protect" mode (due to the abnormal states) then contact pin 4 of the relay will illuminate LD3 (the protect LED on the front panel). Only test the triac for one protect cycle as prolonged testing will heat the triac to a high temperature. Soft Turn On Circuit To reduce the "inrush" current that flows through the line cord from the 120 VAC power source (typical with large linear power supplies), a circuit provides a soft turn on function. When the power switch is turned on, the current that initially flows through the primary of the transformer must flow through SG201 and SG202. These are surgestors that reduce the peak inrush current flow. After about 500 milliseconds a relay's contacts short across the surgestors so that they are not stressed by the current flowing through them under normal operation. A circuit consisting of Q240, Q241, C215, and the associated resistors provides the time delay for the turn on cycle of the relay. The circuit is very similar to the shutdown time delay circuit. Refer to the section on the shutdown circuit for a circuit description. M1147 SHUTDOWN CIRCUIT, FAN CONTROL CIRCUIT, and SOFT TURN ON CIRCUIT: · The shutdown relay and its associated drive circuitry have two possible operating states. · Amplifier on under normal operating conditions. [. . . ] CHECK THE TRANSISTORS FOR ANY SHORT. 12. . TO PLACE THE CONNECTOR BEND RESISTOR R55A TO THE LEFT SO THAT THE CONNECTOR SITS FLUSH AGAINST THE BOARD. CLAMP DETAIL - SEE NOTES 2 AND 3. SEE LAYOUT DIAGRAM M1146 Database History MODEL(S):# 1 2 3 4 5 6 7 8 9 10 11 12 13 1 2 3 4 5 6 7 8 9 10 11 12 13 DATE FEB/12/98 JUN/19/98 JUL/4/98 SEP/10/98 . JAN/27/99 JUL/08/99 AUG/12/99 OCT/12/00 AUG/28/01 SEP/18/01 MAY/03/02 . MAY/16/03 FEB/09/04 SEP/2004 APR/25/06 MAY/02/06 APR/03/07 . [. . . ]