Kenwood TM-V7A Service Manual

CIRCUIT DESCRIPTION
Panel Section (LCD ASSY: B38-0772-15)
The panel section controls serial communications with
the main unit control section, the key input circuit, the
display circuit, and the dimmer circuit through the
microprocessor (iC4).
@Serial communications circuit
A buffer is inserted in order to protect the microproces-
sor ports.
@Key input circuit
There is one microprocessor port for each panel section
key. The PSW key is pulled down and the other keys are
pulled up with software within the microprocessor. The
rotary encoder is input directly to the microprocessor.
@Display circuit
The TM-V7AVE display section is a 152x45-dot full-dot
matrix LCD controlled by two LCD. As shown in Figure 16,
the master IC (IC5) side is connected to 32 common dots
and 80 segment dots and the slave IC (IC6) side is
connected to 13 common dots and 72 segment dots. The
LCD drive voltage is obtained by raising the power supply
voltage (5V) within the IC. Also, the contrast level
(LEBEL8) for resetting is adjusted with R19 to be optimum.
LCD
152X45(dot)
Microprocessor
1C4
Fig.16 Display circuit
@Dimmer circuit
The dimmer circuit switches the lamp brightness to one
of four levels or OFF. (See Table 10.) The current flowing
to the LEDs is varied by selecting resistors from R55 to R58.
Dimmer level P60 P61 P62 P63
1 H L L L
2 L H L L
3 L L H L
4 L L L H
OFF L L L L
Table10 Port logic
OV
LED1 LED2
LED3 LED4
IC4 £2 S tg a)
Microprocessor Se Se Sr Fe
P60
Q13° ont
P61 Wy K
Q12 >
{
P62 Wer "
Qi om
P63 aa
' Fig.17 Dimmer circuit
M-V7A/E
17

Kenwood TM-V7A Specifications

General Specifications

VHF frequency range	144~148MHz
UHF frequency range	438~450MHz (U.S.A/Canada)
Antenna impedance	50Ω
Usable temperature range	-20°C to +60°C (-4°F to +140°F)
Power supply	13.8V DC ±15% (11.7~15.8V)
Grounding method	Negative-ground
Frequency stability	±3ppm (-10°C to +50°C)
Dimensions (W x H x D)	140 x 54.5 x 205.5 mm

Transmitter Specifications

High power output	50W (VHF) / 35W (UHF)
Mid power output	Approx. 10W
Low power output	Approx. 5W
Spurious emissions	-60dB or less
Maximum frequency deviation	±5kHz
Audio distortion	3% or less (at 60% modulation)
Microphone impedance	600Ω

Receiver Specifications

Circuitry	Double conversion
Intermediate frequency (1st / 2nd)	38.85MHz / 450kHz and 45.05MHz / 455kHz
Sensitivity (VHF or UHF band)	0.16μV or less (12dB SINAD)
Sensitivity (Sub VHF or UHF band)	0.25μV or less
Selectivity (-6dB)	12kHz or more
Selectivity (-60dB)	28kHz or less
Squelch sensitivity	0.1μV or less
Audio output	2W or higher (8 ohms, 5% distortion)
Audio output impedance	8Ω

Weight and Dimensions

Weight	1.2 kg (2.6 lb)
Dimensions (W x H x D)	5.51" x 2.15" x 8.09"