Radio Shack TRS-80 Service Manual page 140

5.4.2 Technical Specifications
Environment:
Temperature; Operating Storage
Humidity; Operating Storage
o
to 50 C (32 to 122 F)
-40 to 85 C (-40to 185 F)
85% r.h. Co 35 C (95 F) max.
95% r.h. Co 55 C (131 F) max.
Input Voltage:
90 to 135 VAC rms, 47 to 63 Hz
Input Surge Current:
48 amps max.
Efficiency:
70% min. at full load with 115 VAC rms input
Output Voltages:
V1, + 5.05 VDC
V2, +12 VDC CRT
V3,
+
12 VDC DISK
V4, -12 VDC
Outpuf Power:
continuous 65 watts max.
Output Currenf:
Output Voltage Regulation:
After initially setting V1 , output voltage tolerances under all
conditions of rated line, load, and temperature should re-
main within the following limits:
V1 (+5.05 VDC) +/- 3%
V2 (+ 12 VDC) see 'NOTE
V3
(+ 12 VDC) +/- 5%
V4 (-12VDC) +25%, -8.3%
'NOTE: a) The initial value of V2 must not change by
more than + / - 100mV under the following
load conditions of V3:
- A
step increase in output current from
0.4
A (initial condition) to 2.4 A, decaying
within 60 msec to 2.1 A.
- A step decrease in output current from 2.1
A (initial condition) to 0.4 A.
b) V2 output voltage may vary + /- 5% under all
other conditions of rated line, load, and tem-
perature as defined in the specification.
Condition 1
(Model III use)
Condition 2
(Hard Disk use)
Output
V1
V2
V3
V4
V1
V3
V4
Load
Min.
1.35 A
0.60 A
0.40 A
0.005 A
2.5A
0.75A
0.005 A
Max.
4.0A
1.5A
2.1 A
0.10 A
5.0A
2.0 A'
010 A
Over-Current Protection:
Power supply will shut down before total power exceeds
the point where damage would result. No damage will re-
sult when any output is short circuited continuously with
100 milliohms or less.
Over-Voltage Protection:
The + 5.05 VDC circuit is protected with a "crowbar" circuit
with a trip range of 5.8 to 6.8 VDC.
'NOTE: V2 and V3 connect in parallel to provide the V3
output. The V3 output will support a 5.0 A peak
load which decays fa 1.0 A in approx. 8 seconds.
V1 and V3 must be within specified regulation
when this surge decays to 4.0 A.
Hold-Up Time at Continuous Max Load:
Nominal Line 16 mSec minimum
Low Line 10 mSec minimum
Output Ripple Voltage:
V1 (5.05 VDC)
V2 (+ 12 VDC)
V3 (+ 12 VDC)
V4 (-12VDC)
50mV pop
150mV pop
150mV pop
150mV pop
NOTE: Ripple is fhe composite 100/120 Hz ripple due to
the line, plus the high frequency ripple due to the
power oscillator. Common mode noise which may
be observed due to oscilloscope connections
should be ignored.
147