Monitor/Power Supply Board; Power Transformer - Wyse WY-100 Maintenance Manual

2.0
SRI
The CRT is a 12-inch 90-degree infLection tube with a 20mm neck
diameter. It is mounted directLy to the bezeL of the terminaL via
four screws.
3.0 POWER TRANSFORMER
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The power transformer, mounted to the right-rear of the terminaL
chassis, accepts 115 VAC (or 230 VAC) from the power Line and
transforms these voLtages to Lower LeveLs required by the power
suppLy section of the monitor/power suppLy pcb.
The transformer has two Low voLtage windings. One of them sup-
pLies the +5 voLt power suppLy consisting of U2, Q2 and other
components. The second Low voLtage winding suppLies the +13.5
voLt power suppLy consisting of U1, Q1 and other components as
weLL as the +12 V suppLy (U3) and the -12 V suppLy (U4).
The monitor/power suppLy pcb is mounted verticaLLy on the right
side of the dispLay unit chassis. This pcb contains the power
suppLy, horizontaL and verticaL defLection circuits and the video
circuits of the terminaL.
4.1 +5 VOLT SUPPLY
This circuit consists of U2 (see Appendix G), Q2 and other mis-
ceLLaneous components. U2 is an integrated circuit voLtage
reguLator. VR1 is used to adjust the output of this circuit to
+5 VDC at pin 6, J4. Q2 is the output transistor of the power
suppLy. R23, R24 and R31 Limit the output and protect the voL-
tage reguLator under short-circuit conditions.
4.2 +13.5 VOLT SUPPLY
This circuit consists of U1
(see
Appendix G), Q1, and other
components. U1, is aLso an integrated circuit voLtage reguLa-
tor. VR2 is used to adjust the ouput of the suppLy to 13.5
voLts. R3, R27, R32, and R33 form a current Limiting circuit
that protects the power suppLy under short-circuit conditions.
4.3 +12 VOLT SUPPLY
This circuit consists of U3 (see Appendix G), a three-terminaL
voLtage reguLator ICO. It suppLies +12 voLt DC (at pin 3, J4) to
the Logic board assembLy.
monitor/power suppLy board 3-2