M445 — Extended Range Meter

M445 EXTENDEDRANGE METERMONITOR Refer_to Front Panel drawing B 445-04-002 1) Left ChanneL_VU Meter 5) Termination Switch Meter which indicates the volume units (in dBu) of the input audio Signal. A sinusoidal waveform will indicate '0' On this meter when it's amplitude matches the sensitivity indicated on the liquid crystal display. Under normal operating conditions; this meter indicates the Signal level of the left channel.

When released, the termination switch allows the meter to present & bridging load to the audio source. Once depressed, the impedance selected by the Impedance Selector (Z), is connected across the audio input terminals. Lmpedance_Selector When 'sum and difference mode is selected by mode switch (3) , this meter will display the algebraic sum of the left and right channel audio signal.

This switch terminates the input source with 600 ohms (relaxed) O 150 ohms (engaged): provided the termination Switch has been actuated_ 2) Right Channel VU Meter Monitor Receptacle Operates as (1), except in normal operation right channel audio is displayed In "sum ind differegce" beodec thiseneft indcaghE channel audio. The difference indication is useful for verifying stereo phase coherence. A 1/4" standard TRS (tip-ring-sleeve) stereo receptacle for monitoring the metered audio sunabandividk povidrs olipht ?uGbod quality, high impedance (600 ohms) headphones will provide optimum audio fidelity.

3) Mode_Switch 8) Left and Right Front Panel Inputs When depressed, places the M445 in 'sum and difference mode; otherwise discrete Telephone style, balanced, long frame 1/4" left and right signal levels are displayed on jacks, which have the rear chassis input their associated meters 'normalled" through When plug (ADC PJ-2 Or equivalent) is inserted, the rear HP Filter Swtch chassis input audio is interrupted, allowing any audio present at the front panel to be Normally, the M445 measures the audio measured andlor monitored.

signal across the full audible band_ When aSSigned, the high pass filter attenuates frequencies below it's 75 Hz corner at & rate 9) Power_Switch of -18 dB per octave 3-1

MAAS EXTENDEDRANGEMETERMMONITOR 12) Security Latch 9) Power_Switch When engaged, this latch prevents the M445 from being extracted Powers the meter's active circuitry, exclusive of the battery management system. When docked; engaging the power switch also activates the meter illumination and the power amplifier which drives the speakers_ 13) Speaker_Level Control This rotary control adjusts the level of the audio in the monitor speakers.

10) Liquid Crystal Sensitivity Display 14) Right Channel Speaker Controlled by (11), this display indicates the audio reference level in dBu: When "lo batt" is displayed in the display, the batteries require charging; which is accomplished whenever the meter is "docked" . Should the batteries deplete to a point where accurate measurements are no longer possible, the audio reference display will blank: However; the "lo batt" will still be visible_ In "normal" mode, right channel audio may be monitored via this speaker: In "sum and difference" mode, the difference signal will be present through this speaker: 15) Left Channel Speaker Discrete left channel audio is monitored in this speaker in "normal" mode, while in "sum and difference" , this speaker contains the sum (L+R) signal.

11) Sensitivity Adiustment Control rotary encoder which sets the reference level for a '0' indication on the meters of the M445 . 3-2

M445 EXTENDEDRANGE METERMONITOR Rack Mounted Dock Refer to Rear Panel drawing B445-04-003 16) Power_Input Connector 18) Rear Chassis Connector This connector mates with the ring-lock cable plug from the external power supply. Twenty-four volts (+24V) DC at 500 mA is required by the M445. Audio inputs ("normalled" through the font panel jacks), and audio monitor outputs may be connected to external equipment on this barrier strip 17) Power Fuse 19) Rear Chassis_Security Screw 1/2 amp, slow-blow fuse to protect the entire M44S from a fault condition: captive screw which; when engaged, prevents the meter from being withdrawn from the rack mount frame regardless of the position ofthe front panel lock 3-3

SA14305 MOTHERBOARDASSEMBLY Refer to drawing B 14-305-02-001/2 Control System PowerManagement U13, fast charge controller: The charge controller maintains a time and voltage charge to the batteries whenever it is furnished with +24 volts at P8. Control of the M445 is managed by U12,a one- time programmable (OTP) microcontroller: When power is initially applied, a reset pulse is provided to U12 by R138 and C60.

The oscillator consisting of Xl, R139, C63 and C64; along with circuitry within Ul2 begins to free run: The reset pulse transitions to +5 volts; at which time the software programmed within U1l2 begins to execute_ Battery voltage is monitored by window detector realized by U16 and associated components. The output of UI6A sends a low battery indication to Ul2, which displays the "lo bat" signal in the LCD display.

When the voltage decreases to point where the M445 can no longer function accurately, Ul6B generates signal This allows U12 to disable the meter's audio path, and displays the recharge necessary indication; a5 detailed in the operations section: The status of LK2 and LK3 is read_ Based on the result (see the operational description); the initial level is sent to the LCD display through P7; and to the audio chain's Ul1, U2 through U4, and U6 through U8.

Integrated circuit Ull receives mute signal which calibrates it internally. Relays Kl and K2 are also triggered to place them in the correct state for the chosen initial reference. The audio circuitry within the meter requires bipolar power. To generate negative voltage from the batteries; a small inverting switching power supply is utilized This consists of U14, U15,Q13,and associated components_ quadrature signal, received from the rotary encoder on SA14-304; is read and interpreted by the microcontroller.

By rotating the encoder clockwise; the reference level is increased. Counter-clockwise rotation reduces the reference level: When the M445 is powered from +24 volts DC, integrated circuit regulator Ul8 generates +5 volts DC to power the meter as though it was running off of batteries. Note; Connector P10 and LKI are for factory use onlv: These connectors are used to test the meter's function when first manufactured_ Improper use may result in loss of M445 function_ WBS recommends the use of the supplied NiCd batteries at all times.

If it becomes necessary to utilize batteries which are not those supplied; you must remove LK4. Removing LK4 will disable the charging circuit: Any damage caused to the M445 through failure tO observe this recommendation is not covered under warranty_ The SA14-305 is powered by 'AA NiCd batteries, connected in series through P9 pins 4 and 5. The batteries are always connected to 1-1

SAL4-305 MQTHERBOARDASSEMBLY Refer to drawing B 14-305-02-001/2 Audio Circuitry Audio which is amplified (Or attenuated) by these first three stages is switched into US section A and B, where it is unbalanced and either attenuated by 10 dB, Or transmitted with no net gain into the high pass filter switch and the filter itself: The high pass filter is a third order butterworth filter with -3dB point at 7SHz.

Switch SW4 determines which signal, broadband or filtered enters Ull. Both the left and right channels function similarly. This discussion will pertain to the left channel Differences with the right channel will be noted as necessary. The M445, owing to its large input sensitivity range, uses three different input amplifiers to spread across the full sensitivity range. The CS3310 (U11) is a Stereo Digital Volume Control: Internally; Ull contains two ladders which are digitally controlled by a 16 bit control word.

The control word is fed serially from the microprocessor to pin of Ul1. All level transitions are internally timed to occur at audio Zero crossings, eliminating the "zipper" effect. The gain structure of the M445 is set up so that a nominal -15 dBu level at the output of U11 will generate a 0 VU signal on the front panel meter: The first amplifier; comprised of UL sections A and B, is an instrumentation amplifier input stage with gain of +25 dB.

Magnetically latched relay Kl controls audio flow into this amplifier; while U2 controls the output signal into US section A and B. This amplifier stage is active for front panel sensitivity settings of -60 dB to 335 dB. The second amplifier consists of U3 and associated components. This is essentially unity gain stage, which also has it's input assigned by Kl.

Analog multiplexer U3 simply switches the signal into US or not for front panel sensitivities from -34 dB to 0 dB. The output of Ull is switched through SWS, which controls the mixing of L+R and L-R signals; if selected. The audio signal is then amplified by U9C (+13 dB) Amplifier UlOB generates balanced audio signal which is coupled to the meter; rear panel outputs and the front panel headphone jack through a series of buildout resistors.

A loss stage; consisting of U4 and it's input pad, manages input sensitivities from +] to +30 dB. 1-2

SA14-304LCDENCODERBOARD The SAl4-304 provides physical mounting for the rotary encoder; and the front panel LCD display. To minimize interconnections between the microcontroller on the main circuit board and the LCD; & serial interconnect scheme has been implemented. A serial code generated by the microcontroller is received at Pl on 2 This code containing the sensitivity data, is decoded by Ul, a liquid crystal display driver: The MM5453 stores the received data, and latches it to the LCD display until new data is clocked in.

Resistor Rl and capacitor Cl provide timing for a free running oscillator which drives the LCD backplane. Rotary encoder PUI, generates quadrature signal when rotated. When rotated in & clockwise direction; the output of pin 1 will lead pin 2 by 45 degrees: Pin 2 leads pin 1 when PUI is rotated anti-clockwise. This signal is passed tO the microcontroller where it is decoded to & sensitiv- ity adjustment signal for the meter: 1-1

M445 EXTENDED RANGE METER/MONITOR

Initial Inspection

The M445 carton should contain:

1 - This User's Manual 1 - ac adapter complete with connector. 1- M445 meter 1- Rackmount speaker assembly

Installation

The ac adapter, meter, and rack mount assembly should all be separated for installation.

1) Place the rackmount assembly in your equipment rack. Finger tighten the four screws.

2) Carefully dock the M445 in the rack assembly. It may be necessary to adjust the rack frame slightly so that the meter will insert and extract easily. Tighten the four rack screws while the meter is docked.

3) At the rear of your rack, insert and lock the power connector. Connect your audio source and power amplifier (if needed) to the barrier strip and plug the unit in.

4) The meter will operate when the power switch is engaged on the front panel.

Note: Before using the meter in portable mode, it should be left docked overnight to ensure that the batteries are fully exercised and charged.

Configuration Selection

The M445 is factory configured to return to +4 dBu reference sensitivity when initialized. Should your prefer 0 dBu or +8 dBu as the reference sensitivity, you can configure the M445 to reset to this state by changing two internal shorting clips.

Simply remove the top cover of the meter. To set a 0 dBu initial reference, remove the shorting clip across LK3, ensuring that the LK2 clip remains in place. For configuration to +8 dBu reference level, leave LK3 in place and remove LK2.

It is a good idea to save any shorting clips that you remove for possible future use. SA14-305 Motherboard Assembly WBS SA14-305

SA14-304 LCD, Encoder Assembly " SA14-304

SA14-307 Meter Light Bar Assembly " SA14-307

SA14-311 Speaker Amplifier Assembly " SA14-311

F1, F2 Fuse, 0.5 Amp S.B. Buss MDL.500

JACK 1 Headset Jack, Long Bushing Switchcraft NL-114B

JACK 2 Jack, 3 Conductor, Single Long Frame ADC PJ339

JACK 3 Jack, 3 Conductor, Single Long Frame ADC PJ339

METER 1 VU Meter "A" Wilbac Bach Simpson 1823

METER 2 VU Meter "A" Wilbac Bach Simpson 1823

TS1 Terminal Block Cinch 12-140

RECEPTACLE Chassis Receptacle Preh 71206-021

SPEAKER 1 Speaker with Shielded Ferrite Magnet Misco SD22S

SPEAKER 2 Speaker with Shielded Ferrite Magnet " SD22S

P1 Connector, 24P, D-Ribbon 3M 3548-1001

J4 Connector, 24P, D-Ribbon 3M 3549-1000

305J1,305J2 Connector, 6S Female Socket Panduit CE100F26-6 305J7,304J1, 311J1,311J2

305J9 Connector, 6S Female Socket Panduit CE100F22-6

305J3,305J5 Connector, 3S Female Socket Panduit CE100F26-3 305J6

305J4,311J3 Connector, 3S Female Socket Panduit CE100F22-3

305J8 Connector, 26S Ribbon Interface 3M 3399-6600

BATTERY Battery AA, Rechargeable Panasonic P-60AA

AII Ward-Beck Systems Ltd., products are warranted against defective materials and workmanship for 2 period of one year from the date of shipment . Ward-Beck Systems Ltd , will repair or replace at its option and without charge, all said products or parts thereof which upon factory inspection prove to be defective during the warranty period, provided that: the original serial numbers are intact and have not been tampered with , 2) the purchaser shall return any equipment or parts thereof to Ward-Beck Systems Ltd , only after obtaining prior authorization and shipping instructions from the factory (Ward-Beck Systems Ltd.

reserves the right to inspect or repair equipment on the purchaser's premises) , and 3) the purchaser assumes the obligation for all expenses incurred in connection with the shipping and return of such goods one authorization has been obtained. This warranty does not cover items normally considered expendable, such as fuses and lamps_ This warranty does not cover damages caused by misuse, accident; neglect; unauthorized alteration, repair by unauthorized personnel, or damage caused by an act of God; war or civil insurrection.

In no event shall Ward-Beck Systems Ltd , be liable for consequential damages. Ward-Beck Systems Ltd., shall have the rights to final determination as to the application of this warranty. Ward-Beck Systems Ltd,, reserves the right; at any time and without notice, to make changes in its equipment, components, specifications, or designs, as may be warranted by progress in state-of-the-art or technology Ward-Beck Systems Ltd , reserves the right to make design changes_ additions to, and improvements in its products, without obligation to install such revisions in products previously manufactured.

The warranty set forth herein is in lieu of all other warranties expressed or implied, including the warranties of merchantability and fitness_ WARD-BECK SYSTEMS LTD: 455 Milner Avenue, Unit1O, Toronto, Ontario, Canada MIB 2K4 Tel: (416) 335-5999,Fax: (416) 335-5202, Toll Free; 1-800-771-2556 Web site: www.wbsltd .com, E-mail: [e-mail removed]