Disassembly; Alignment Preparation - Realistic trc-448 Service Manual

FIGURE 1
NOISE BLANKER
Noise pulses are amplified by IC-201 and detected by D236 and D237. The detected pulses are then
amplified by Q226 and Q227. This applies a positive pulse to the base of Q228, thus decreasing its collector
impedance to shunt the Q225 gate impedance during the duration of the noise pulses. The most objec-
tionable noise pulse frequencies are distributed around 40 MHz, thus T213 and T214 are tuned to this
frequency.
MIX
Q225
RF AMP
Q223, Q224
IF
VV V
BLANKER
Q228
nn
N
T213
NOISE
AMP
IC-201
T214
NOISE
DET
D236, D237
AMP
Q226, Q227
DISASSEMBLY
Refer to Figure 1.
Step 1: Remove two bracket screwsAO and the Bracket.
Step 2: Remove 4 cabinet mounting screws ®
(two from each side).
Step 3: Remove Cabinet Top and Bottom.
ALIGNMENT PREPARATION
TEST EQUIPMENT REQUIRED
1. Oscilloscope
2. AC VTVM
3. DC VTVM
4. Frequency Counter with level meter
5. AUDIO Signal Generator
6. Sweep Generator (0 50 MHz)
7. Power meter (50 2)
8. 50 2, 10 W dummy load
9. 2-tone generator (500 Hz — 2.5 kHz)
10. RF Signal Generator (0 30 MHz)
11. Pulse Generator
12. Monitor Receiver (54 MHz)
(or Spectrum Analyier)