McIntosh ML10C Loudspeaker System Service Information.pdf
ML IOC LOUDSPEAKER SYSTEM SERVICE INFORMATION SERIAL NO. BH1001 AND ABOVE 38-840 SPECIFICATIONS SPEAKER SIZE Woofer 101 dia. frame size (8-3/8 dia. radiator) Mid-range 1-1/2 dia. dome radiator Tweeter 1-5/8 dia. coaxial super radiator CROSSOVER FREQUENCIES 1000Hz & 7000Hz IMPEDANCE 8n Nornina1 POWER HANDLING: Sine wave steady state SINE WAVE POWER LIMIT IN WATTS FREQUENCY IN Hz Avoid operating the speaker system with sustained sine wave signals at power levels greater than the indicated limits. Permanent damage may result. POWER HANDLING: Program Material High energy peaks normal to orchestral music are easily and faithfully reproduced by the speaker system. These peaks are of relatively short duration and do not produce the heating effect caused by sustained tone operation. The ML-L speaker system will handle up to 300 watts of orchestral music program material. Care must be taken, however, to use a power amplifier that has an adequate power rating. If a low power amplifier is used, the loudest passages may be clipped by the amplifier. This clipping will cause the speaker to sound distorted. The large harmonic content of a badly clipped signal can cause excessive heating and re sulting damage to the high frequency speaker elements and crossover network. OUTPUT LEVEL In a reverberant room the system will nominally produce an 89dB sound pressure level when driven at a one watt level referred to 8n. SPEAKER LOCATION LSI REMOVE LSI TO SERVICE CROSSOVER NETWORK SCHEMATIC NOTES In early units LS3 is 036-005 16fl impedance. Acoustic output will be the same. LS3 may be replaced with 036-012 8fi impedance. CROSSOVER NETWORK TWO DIFFERENT CIRCUIT BOARDS HAVE BEEN USED. THE SCHEMATIC IS THE SAME FOR BOTH. CROSSOVER NETWO C2 TuF R2 5JI 0.2 mH ASSEMBLY 044-472 LU I- i ro oo _) SYSTEM SCHEMATIC SERVICE NOTES Speaker element failure can be quickly located by using FM hiss at a low power level. Listen at each speaker to verify if all the speakers are at least working. A low power (1-5 watt) sine wave sweep 20-20kHz can be used as a quick check for distortion. A speaker element with obvious distortion must be replaced. To determine if the speaker element is dead, remove the speaker and momentarily connect a 1.5 to 6V battery across the terminals. If no sound is heard, the speaker element must be replaced. The crossover network must be inspected when burned out speaker elements are replaced. The net work must also be inspected if a speaker element produces sound with the battery test but does not play when connected in the system. The woofer must be removed to get to the crossover. Check for bad connections, broken wires, etc. Be sure to check the resistors mounted on the plate underneath the printed circuit board. A broken lead on these resistors can also be the cause of intermittent or partial failure of the system. When a system has been driven excessively hard by a clipped amplifier for long periods of time, the dome mid-range may appear to have weak or no output. In addition to a burned out mid-range, the 7pF capacitor may also be damaged. Thiswii) be evident if a new mid-range has been installed and also appears to have weak or no output. Use only McIntosh replacement capacitors. These have been specially selected for low ESR. Use RTV silicone rubber under replacement parts mounted on the printed circuit board. |n addition to the solder connections, this insures a vibration free bond to the board. The solid colored wire (other than black) always goes to the red marked terminal on the speaker. This is the positive terminal. If the polarity of a speaker is unknown, momentarily connect a 1.5 to 6V battery to the terminals. When the cone moves away from the magnet, it means the + terminal of the battery is connected to the + terminal of the speaker. When installing speakers or crossover network in the cabinet, care must be taken to insure a tight air seal to the cabinet. Replace the black caulking material or foam gasket if necessary. Mortite caulking compound or equivalent could be substituted but care must be taken that it will not be visible after the part is installed. If a woofer screw strips out in the wood of the cabinet, the speaker can be rotated and new mounting holes drilled. After the system is reassembled, it must be checked for air leaks. This can be done by putting a 20Hz sine wave into the system at 50 watts (20 volts). By listening around the speakers closely for hissing sounds, areas can be located that must be sealed. The system must also be swept from 20Hz to 250Hz at 25 watts (14 volts) to insure there are no vibrations due to wires hitting the woofer cone, etc. All defective parts must be packed well and returned to McIntosh Laboratory Loudspeaker Division. REPLACEMENT PARTS All parts not listed are common items obtain able from radio parts jobbers. Replacement parts may be obtained when ordered by PART NUMBER from: McIntosh Laboratory, Inc. Customer Service Department 2 Chambers Street Binghamton, New York 13903 (telephone 607-723-3512) CAPACITORS Symbol Number Description Part Number Cl Elect. 25pF 066-189 C2 Mylar 7t*F 100V 064-123 C3 Mylar IpF 250V 064-104 CHOKES LI Choke 5mH 122-124 L2 Choke .2mH 122-123 L3 Choke ImH 122-134 L4 Choke .2mH 122-123 RESISTORS Rl ,2 Wirewound 139-082 R3 Wirewound 4fi 139-086 LOUDSPEAKERS LSI 10 Woofer 036-028 LS2 1-1/2 Dome Midrange 036-027 LS3 2-1/4 Tweeter 036-012 MISCELLANEOUS ITEMS Terminal Red 084-086 Terminal Black 084-087 Shipping Carton 033-176 Grille 030-012 Front Panel Assy. 044-364 Speaker Gasket 2-1/4 Tweeter 094-096 Speaker Gasket 1-1/2 Dome 094-103 Speaker Gasket 10 Woofer 094-093 Network Gasket 094-106 CrtiZ.L AbfipU-A3 l 1 V - 6 5 3 IMntosb MclNTOSH LOUDSPEAKER DIVISION 2 CHAMBERS ST., BINGHAMTON, N.Y. 13303
