REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Friday 8 March 2019

SONY XM-2002GTW CAR AMPLIFIER BIAS ADJUSTMENT AND POWER SUPPLY CIRCUIT

SONY XM-2002GTW CAR AMPLIFIER BIAS ADJUSTMENT AND POWER SUPPLY CIRCUIT

SONY XM-2002GTW 

CAR AMPLIFIER 

BIAS ADJUSTMENT AND POWER SUPPLY CIRCUIT 

Bias Adjustment
Note : In Bias Adjustment, adjust RV103 if any of Q108 through Q113 are replaced. Adjust RV203 if any of Q208 through Q213 are replaced.
Condition : This adjustment should be performed about one minute after the remote mode is turned on at a room temperature of about 25°C.
Procedure :
1. Turn the variable resistors RV103 (L-CH) and RV203 (R-CH) full clockwise as seen from the component side to minimize the bias current.
2. The input signal is to be no signal.
3. Apply the voltage to the B+ and REM terminals from the stabilized power supply and gradually increase it up to 12.0 V while checking for any unusual current.
4. Adjust each of RV103 (L-CH) and RV203 (R-CH) so that the power current of the stabilized power supply is increased in steps of 700 mA (total of 1.4 A).
5. After adjustment, check that the power current is at 1.65 to 2.05 A.

Power Connection Wires
If you have the factory original or some other car audio unit without a remote output on the amplifier, connect the remote input terminal (REMOTE) to the accessory power supply. In High Level Input Connection, car audio unit can also be activated without need for REMOTE connection. However, this function is not guaranteed for all car units

As the Monaural Amplifier for a Subwoofer
For details on the settings of switches and controls, refer to “Location and Function of Controls.”
Note
If you wish to use a subwoofer as a monaural speaker, connect the speaker as illustrated above. The output signals to the subwoofer will be the combination of the both right and left output signals.

Caution
# Before making any connections, disconnect the ground terminal of the car battery to avoid short circuits.
# Be sure to use speakers with an adequate power rating. If you use small capacity speakers, they may be damaged.
# Do not connect the # terminal of the speaker system to the car chassis, and do not connect the # terminal of the right speaker with that of the left speaker.
# This is a phase-inverted Amplifier.
# Install the input and output cords away from the power supply wire as running them close together can generate some interference noise.
# This unit is a high powered amplifier. Therefore, it may not perform to its full potential if used with the speaker cords supplied with the car.
# If your car is equipped with a computer system for navigation or some other purpose, do not remove the ground wire from the car battery. If you disconnect the wire, the computer memory may be erased. To avoid short circuits when making connections,  disconnect the +12 V power supply wire until all the other wires have been connected.
CIRCUIT DIAGRAM 
CLICK ON THE IMAGE TO ZOOM IN