Teac EU-34TB, Service Manual

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3.  TUNER

Either a PLL or a VST tuner is used as a tuner.

UV1336 (VHF/UHF) is used as a PLL tuner. For only PAL B/G applications UV 1316 is used as the PLL tuner.

Channel coverage of UV1316:

               OFF-AIR CHANNELS                                                           CABLE CHANNELS

BAND

CHANNELS

FREQUENCY

CHANNELS

FREQUENCY

RANGE (MHz)

RANGE (MHz)

Low Band

E2 to C

48.25 to 82.25 

(1)

S01 to S08

69.25 to 154.25

Mid Band

E5 to E12

175.25 to 224.25

S09 to S38

161.25 to 439.25

High Band

E21 to E69

471.25 to 855.25 

(2)

S39 to S41

447.25 to 463.25

(1). 

Enough margin is available to tune down to 45.25 MHz.

(2).

 Enough margin is available to tune up to 863.25 MHz.

Noise

Typical

Max.

Gain

   Min.

Typical

Max.

Low band :  5dB

9dB

All channels

:  38dB

44dB

52dB

Mid band :  5dB

9dB

Gain Taper (of-air channels) :     -

   -

8dB

High band :  6dB

9dB

Channel Coverage UV1336:

      BAND

CHANNELS

FREQUENCY

RANGE (MHz)

Low Band

2 to D

55.25 to 139.25

Mid Band

E to PP

145.25 to 391.25

High Band

QQ to 69

397.25 to 801.25

Noise

 is typically 6dB for all channels. 

Gain 

is minimum 38dB and maximum 50dB for all channels.

4. SOUND OUTPUT STAGE TDA2614

TDA2614 is used as the AF output amplifier for mono applications. It is supplied by ±12VDC coming from a separate winding in the

SMPS transformer. An output power of 2.5W (THD=0.5%) can be delivered into an 16 ohm load.

5. VERTICAL OUTPUT STAGE WITH TDA 8356

The TDA 8356 vertical deflection circuit is used in 90° deflection systems with field frequencies from

50 up to 120Hz. With its bridge configuration the deflection output can be DC coupled with few external components.

Only a single supply voltage for the scan and a second supply for the flyback are needed.

The drive voltage is amplified by an amplifier and fed to two amplifiers, one is inverting and the other is a non inverting amplifier.

The outputs (pins 7 and 4) are connected to the series connection of the vertical deflection coil and feedback resistor Rsense

(R702//R703). The voltage across Rsense is fed via pin 9 to correction amplifier, to obtain a deflection current which is proportional

to the drive voltage. The supply voltage for the TDA 8356 is 15VDC at pin 3. The supply voltage generator has a separate

supply voltage of 45VDC at pin 6.

6. VIDEO OUTPUT AMPLIFIER TDA6107Q

The TDA6107Q consists of three monolithic video output amplifiers. The amplifier can be seen as an operational amplifier

with negative feedback.

The advantage of negative feedback is that the amplifier characteristics do not play an important role up to certain frequencies.

The internal flash diodes protect the amplifiers against flash over in the picture tube.

The only protections required at the cathode outputs are a flash resistor and a sparkgap.

The TDA6107Q has an internal thermal protection circuit which gives a decrease of the slew rate at high temperatures.

Furthermore, the device needs only one power supply voltage (Vdd).

In contrast to previous types of DMOS video amplifiers, all the external resistors (Rf, Ri and Ra) are integrated, so the gain is fixed

and saves 9 resistors.

Furthermore, the reference voltage is integrated, it saves a resistor divider and a decoupling capacitor. So, the replacement

value of the TDA6107Q is very high.

The TDA6107Q is provided with a black current data pin. Since TDA884X is used as drive device, no adjustments are required

for gain and black setting, as the TDA884X has I²C white point adjustment and black current set-up.

7. POWER SUPPLY (SMPS)

The DC voltages required at various parts of the chassis are provided by an SMPS transformer controlled by the IC MC44604

which is designed for driving, controlling and protecting switching transistor of SMPS. The transformer produces 150/115V for

FBT input, ±14V for audio output IC, S+5V for microcontroller, +15V for vertical output (field scan) and +33V for tuner and some

other ICs and transistors.