AUDIO TELEX DCM500 Operation & User’s Manual

+61 2 9647 1411 www.australianmonitor.com.au SERVICE INFORMATION AUDIO TELEX DCM500 POWER AMPLIFIER CONTENTS: OPERATION MANUAL CIRCUIT DESCRIPTION SET-UP / TEST PROCEDURE SCHEMATIC DIAGRAMS PCB OVERLAYS COMPONENT LISTS

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Product Description The DCM500 is a 500 watt power amplifier in a two rack unit (2RLI) chassis suitable for table or direct 19" rack mounting. The DCM500 has outputs for 70 & 100 volts and 4 ohms. It has a balanced input of 10K ohms. The DCM500 will operate from 240 V AC @ 50 IIz or I I 0 VAC @ 60 Hz (not user selectable, internal, factory adjushent only, specifi at the time of ordering) or 24 VDC and will meet it's full performance specification on either voltage supply. The DCM500 also features a DC battery trickle charge facility, slow start on powering up (to reduce inrush current problems), auto-sensing ftn cooling, plus overload short circuit and over ternperature protection. The maximum recommended load for the DCM500 is 20 ohms. lnitial Set Up There is an unlabelled, screwdriver adjustable output level control located centrally on the front panel of the DCM500. Turning this control in the clockwise direction will increase the power output, turning this comtrol in a counter-clockwise direction will reduce the power output. The ftctory default setting for this conkol is such that a I volt input will give a 100 volt output. Front Panel Gontrols Output Level: The output level control is unlabelled, r@essed (screwdriver adjustable) and is located in the centre of the front panel, just to the right of the DCM Series logo. Tuming the control clockwise will increase the output of the DCM500 towards it's manimum output level wtrile tuming the control counter-clockwise will decrease the output level. Adjust this control for the desired output level depending on the level of the input signal (from a mixer or other signal source). The factory defrult setting for this control is such that a I volt input will give a 100 volt output. POWef SWitch: The rocker switch located in the front centre of the panel turns AC power on to the DCM500. Rocking the power switch to the right to turns the AC powetr 'on'. When the AC power is 'on', a gree,lr LED will glow in the amplifier status display windorv. Please note that this switch does not switch DC voltage. If a DC voltage supply is connected to the DCM500, the amplifier will operate as sfi)n as the connection is made, regardless of the position of the AC power switch. If both an AC and DC voltage supply are connected and you rock the AC power switch to the 'off position, the DCM500 will automatically continue to op€rate normally from the DC supply (and the 'mains failure' LED in the amplifier status display window will also glow undo these comditions; see the amplifio status display window section under Frurt Panel Cmtols later in this manual). Gooling Fans (Air lntake): rhe cooling fans (two installed in the case of the DCM500) are ternperature sensitive and only switch orr when the temperature of the DCM500 had reached a pre-determined range. The fans will stay on and only switch off again mce the temperature of the DCM500 has fallen below a pre-determined level. So, the ftct that the fans are not operating at any time (and most noticeably to the operator at turn-on) does not mean that the amplifier is faulty in any way, just that it is o'perating within a temperature range that does not need frn cooling for adequate heat dissipation. If the DCM500 is operating curtinually at c.onservative levels and proper load conditions, it is possible that the cooling fans will not switch on at anytime during normal operation. When operating, the fans cause air flow from the front to the rear of the DCM500. Continuednext page3

Please refer to Figwe #1 on the back page of this instruction sheet with numerical reference as follows: High Temperature: firis red LED glows if the fan has failed and the amplifio has been shut down by its' temperature control circuity. If this LED is glowing and the fans have not failed, it means that the amplifier is operating in an ambient environment that it naturally too hot for fan cooling to make any difference to the temperature of the amplifier. PoWef: This LED glows green if AC power is switched on to the DCM500. Note that this LED does not indicate the pres€nce ofa DC supply voltage lUlains Failure: The LED glows red if there is a failure in the AC mains power supply. However, this LED will only glow if there is a DC supply voltage present. If no DC supply voltage is present then this LED will not glow. Output Level VU lleter: A 10 segment LED W meter is provided to give an indication of the output signal level of the DCM500 from -25 to +3 dB. For normal operation the LED's should oscillate in and out of the red zone. If the LED's in the red zone are lit continually, the,n the output level control (or the level of the input signal to the DCM500) should be adjusted to reduce the output level. Too much output level can cause distortion and possible damage to the connected speaker qystem. Rear Panel Connections Please refer to Figure #2 on the back page of these instructions with numerical references as follows: 3 pin lEC, AC mains power inlet. The operating voltage is 240 VAC @ 50llzor l t0 vtc @ 60 rIz. The AC power voltage level is not externally user selectable but is ftctory pre-set (via transformo selection). The inl* is equipped with an inbuilt AC fuse holder fitted with a l0 Amp slow blow fuse plus one spare fuse. Power consumption is 800 VA. Please ensure that the mains power cord is disconnected before attempting to check or replace this fuse. Output terminal strip . Reading from left to right these connections are as follows: Common for low impedance 4 Ohms Common for constant voltage systems 70 volts 100 volts 24 VDC power connectio[. The left side red post is the + (positive) terminal while the right side black posr is the - (negative) terminal. The DC current drain is 30 Amps, maximum at full power. This socket also provides trickle charge to a DC battery supply (if connected) when the DCM500 is operated from AC mains power. The level of trickle charge is 30b me" maximum. Twin DC low voltage, fuse receptacles. Access the DC tuses is by turning the cap half a turn count€r- clockwisewith a screwdriver. The value of the fuses is 35 Amps. Pleasc ensure that the AC powerswitch is in the.ofr position and that the mains power cord is disconnected before attenpting to check or replace this frrse lnput (& parallel_output) XLR signal connectiolr. The input to the DCM500 is ransformer balanced @ 10K ohms. The pin configuration of both sockets is as follows: pin #l-earth; pin #2-active (high, +); pin #3-active (lol", -j. The output socket is to allow the original input signal to be fed on to another amplifier. As these trvo sockets are wired in passive parallel, the failure of any one amplifier will not affect the sigrral flowing through that amplifier to anotho amplifier.

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