User manual TEKTRONIX 453A

[. . . ] ' ' 1 ST RU CT I 0 UAL Se r ial Num ber Te k tro n ix, Inc . Box 500 0 Beaverto n , Oregon 97005 " Phone : 644-0161 " Cables : Te k tronix 171 . WARRANTYdefective materials and workmanship for one yea r. Tektronix Jnstru me nts are : warranted against . respect, to the - warranty, Any ' . questions w ith mentione d abo ve, shou ld- pe 'taken up with yo u r Tektronix Field' Engineer or re presentative. replacement parts should be directed to the Tektronix Fie l d Office or rep resentativ e in Your area_ This procedure will assu re you' the fastest possible 'service. [. . . ] 3-17 sh ows detailed block d iagram of t h e Power Su pp ly circuit . sc h ematic of t h is circuit is s h own on d iagram 17 at t h e rear of t h is manual . Power In put Power is a pp lie d to t h e primary of transformer 1101 th roug h th e 115-volt line fuse F 1101, PO WER switc h S1101, th ermal cutout S1104, Voltage Selector switc h S1102, an d Range Selector switc h S1103 . T h e Voltage Circ uit Descri ption-453/R 453A R ange Selector ' 51103 51102 Voltage Selector P OWER S1101 , + F1204 +150 V (unreg) +150 V R ectifier CR 1202, CR 1212 +75 V R ectifier C R1172 - +75 V +75 V Cu rren t L imitin g 011 89 R 1187 ~ +12 volts to H igh- Voltage Oscillator, CRT Circuit Unreg u late d Amplifier 01184, \ 1193 ~ -12 V ` Feedbac k +75 V Input (90-136 V, 180-272 V, AC, RMS) Line R ectifier CR 1142 +12 V +12 V +12 V -~ Current Power Input R 1159 01159 Limiting Amplifier 01154, \01163 +12 V F eed b ac k -12 V -12 V Rectifier C R1112 r l_~ -12 V C urrent 01129 A R egulator 01137 -, 2 V Series Limiting Amplifier 01114, 01124, 01133 --'j Feedback -, 2-V R eference V R 1114 R 1129 6. 3 Volt RMS Sou rce R 1107 DS1107 (~) 1 N R 1108 R 1104 1 DS1108 1DS1109~ Line trigger sign al to Trigger Generators ~ -12 POW WER LLUM ~ SCALE R 1105 F ig . 3-17 . Power Supply d etaile d bloc k d iagram . 3- 29 Circuit Descri ption-453 /R453A Selector switch S1102 connects the s plit primaries of T1101 in parallel for 115-volt nominal o peration, or in series for 230-volt nominal o peration . second line fuse, F1102, is connected into this circuit when the Voltage Selector switch is set to the 230 V position to provi de the correct protection for 230-volt o peration (F 1102 current rating is one-half of F 1101) . Range Selector switch S1103 allows the instrument to regulate correctly on h igher or lower than normal line voltages . E ach half of the primary has ta ps above an d below the nominal voltage point (115 or 230 volts) . As Range Selector switch S1103 is switched from LO to to HI, more turns are effectively added to the primary win d ing and the turns ratio is decreased . This configuration compensates for h igher or lower than normal line voltage to extend the regulating range of the Low-Voltage P ower Sup p ly . Thermal cutout S1104 provi d es thermal protection for this instrument . If the internal tem perature of the instrument exceed s safe o perating level, S1104 o pens to interru pt the a pp lie d power . When the temperature returns to safe level, S1 104 automatically closes to re-a pp ly the power . the base of Q1124 than established by the -12 V Reference stage at the base of Q1114 . Since the transistor with the more positive base controls the con duction of the d ifferential am p lifier, the out put current at the collector of Q1114 d ecreases . This dec rease in out put from Q1114 allows more current to flow through Q1133 to result in increase d con duction of -12 V Series Regulator Q1137, The loa d current increases and the out put voltage of this su pp ly also increases (more negative) . As result, the feedback voltage to the base of Q1124 returns to the same level as the base of Q1 1 14 . Similarly, if the out put level of this su pp ly increases (more negative), the out put current of Q1114 increases . The fee dback through Q1133 reduces the conduction of the -12 V Series Regulator to decrease the out put voltage of this su pp ly, divider 131121-131122-R1123 . R1122 in this divi der is adjustable to set the out put level of this su pp ly . Regulation occurs as follows : If the out put level of this su pp ly decreases (less negative) due to an increase in loa d , or decrease in in put voltage (as result of line voltage changes or ri pp le), the voltage across divider R 1121-R 1 122-R 1 123 Be creases also . This results in more positive feedback level at -12-Volt Supply The following discussion inclu des the d escri ption of the -12 V Rectifier, -12 V Series Regulator, -12 V Feedback Am p lifier, -12 V Reference, and -12 V Current L imiting stages . Since these stages are closely relate d in the production of the -12-volt regulate d out put voltage, their o p eration is most easily un derstoo d when discussed as unit . put at the secon dary of T1 101 to provide the unregulated voltage source for this su pp ly . CR1112 is connected as bridge rectifier an d its out p ut voltage is filtered by C1112 before it is a pp lied to the -12 V Series Regulator Q1137 . [. . . ] 5-30 -31 -32 -33 -34 -35 -36 -37 -38 -39 Te k tro n ix Part No . 426-0363-01 -----212-0040-00 213-0129-00 361-0120-00 214-0881-00 -----211-0503-00 351-0104-00 355-0114-00 -----210-0411-00 210-0011-00 Ser ial/ M od el No . E ff Disc Q t 1 4 2 1 1 2 1 4 1 1 zss Desc r i p tio n FR A ME, suppo rt, left mo u nting ha r dware : (not in cl u de d /frame) . 375 SC REW, 8-32x0 i n c h , 100° cs k, FH S SC REW, 0 inc h , HSS . 75 . 25-20x0 S PAC ER , ste p ped mo u nti ng h ard ware : (not in cl u de d / h inge) SC REW, 6-32x0 i n c h , PH S . 188 G U ID E (pair), / ha rd wa re ST U D mo u nting h a rdwa re for eac h : ( n ot in clu ded /st ud) . 438 . 25-20x0 NU T, h ex . , 0 i n ch WAS HER, loc k , i n ter n al, 0 . 25 lD 0 . 469 i n c h OD HI N G E s 5 453 R 453 OSCILLOSCOPE Fi g. 010-6061-01 012-0076-00 012-0092-00 159-0021-00 159-0022-00 159-0025-00 159-0028-00 070-1105-00 070-1089-00 Serial/M od el No . [. . . ]