M485B — SERIES REG BASE

M4858 +/ 25 POWER SUPPLY The M485B is +/ - 25 vol[ dc power supply which is capable of del i vering currents of up t0 amperes. The primary winding of the power transformer T1 is designed for operation from nominal 110/220 volt ac, 50/60 Hz Tine. The secondary of Ti feeds bridge rectifier CRI-CRL and filter cap- acitors C1 C2, developing unregulated dc vollages of +/-40 volts. These dc voltages feed sfries regulator transistors 01 and 02 . The reference ampli fiers and regulator driver circuitry Jocaled On the 1-117 regulator card derives its power fromi the +/-40 volts as well . The regulated +/-25 volts appears on respectively _ TB2 terminals 1,2 and 7,8 Clamping diodes CRS-CR8 prevent any supply voltage reversals from damaging the regulator circuitry. 21

WAAD-BECK Systems LTD; PARTS List M/858 25 POWER SUPPLY PART

1-117 REGULATOR BOARD The 1-117 Regulator is printed circuit board unil. It is used in number of WBS Power Supplies and contains the majority of the active circuitry of these units. The +25 regulator consists of 21 and booster transistor 01 _ 21 contains internal current imiting and foldback circuits. The voltage drop developed across the current sensing resistor R3 on the main chassis i5 fed t0 pin of 21 via the voltage divider R7/R8 . When the supply current reaches approximately 2.5 amperes; foldback current limiting sels in With the supply output shorted, the current is imited to approximately 0.75 amperes Feedback sensing of the +25 i5 brought back frot the main framc via PCB connector pin 6 , and is coupled to pin of 21 via thc voltage divider consisting of R1? RIB and R15 The output of 21 controls the basc current of 01 In turn, 01 drives the positive series regulator 01 On the main frame by way of edge connector pin 21 The -25 V regulator consists of 22 and transistors 04 through 06 . The negative side of R15 is connected t0 22, pin By varying R14, the negative output voltage is con trolled Simultareously , via 22 , Pin and the voltage divider R17 , R18 and R15, the positive output voltage will respond proportionally to the operation of R14 Thus, both positive and negative voltages wi track . R18 Serves as differential control valtage while decreasing the other Adjusting Ria wil| increase one Booster transistors 04 and 05 are operated from the output of 22 (pin 7) and in [Urn drive the negativc Series regulator 02 On the main frame via pin of the edge connector. Transistor 06 is operaled by the voltage developed across the current sensing resistor Rh (on the main frame) As the current rises to predetermined value, 06 will conduct and reduce the drive current from 22, pin 02 wili sense the loss of either output voltage. Normally 02 is saturaled, resulting in 03 being switched off_ In the event of failurc of either supply voltage, 02 wil become nonconductive and 03 will saturate, thereby remov ing the reference currents from Z1 and 22, causing both regulators to shut down 1-117-1-1

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M485p +/ POWERSUPPLX The M485B +/ - delivering currents up vol dc power supply which amperes capable The primary winding the power transformer operation from nominal 110/220 vol - ac, 50/60 Hz Iine designed for The secondary Teeds bridge rectifier CRI-CRL and filter cap- acitors C2 , developing unregulated ac voltages /-40 volts These dc voltages feed series regulator transistors and 02 The reference amplifiers and regulator driver circuitry located (n the 1-117 regulator card derives its power from the +/-40 volts as well.

The regulaled +/-25 volts appears respective TB2 terminals 1,2 and 7 , 8 Clamping diodes CRS-CR8 prevent any supply voltage reversals from damaging the regulator circuitry

M485B +/- 25 POWER SUPPLY DC Output: 1/ - 25 volts at load currents frorri amperes. to Line Regulation: 0 .1% for Iine variations from 105 Ta 125 Or from 210 to 250 volts ac respectively Load Regulation: 0 .1% for load varations From zero [0 full load Ripple and Noise: Less than 500 microvolts RMS for all Iine and load conditions specified above. Internal Impedance: Less than 0 . ohm fromi dc Ta 20 kHz Stability: 0.1 volts measured over an after 30 minutes warmiup hour period, Protection: Overcurrent and short circuit foldback. Overvoltage crowbar AC Input: 110/220 volts aC, nominal 50/60 Hz . Maximum input Power: 525 VA. Ambient Temperature: t0 40 degrees Celsius at rated output. Dimensions: 13.5" wide 6.2" high 4.0" deep (340 mm 156 MM 100 mm ) Weight 12 Lbs (5.5 kg) Accessories: Power cord, AC Fuse and switch.

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