JVC I'Art AV-27MF36 Installation guide

JVC Television
Power Supply Training

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INTRODUCTION
After this course, you will learn:
• The operation of Switching supplies
• Details about the regulator IC
• Operation of the Power Supply Modes
• The operation of the Power Factor Circuit
• Troubleshooting procedures useful in
diagnosing defective components
• Some failures and their symptoms
TELEVISION

AGENDA
• Model Identification
• Service Manual Supplements
• Switching Power Supply
• Power Supply Components
• Basic Switching
• Switching Device
• Switching Operation
• Switching Review
• Power Factor circuit
• Troubleshooting techniques
TELEVISION

TELEVISION MODEL IDENTIFICATION

• Prior to service, it is always wise to verify the Model and Version to
ensure that the correct Service manuals and Schematics are being used.
• In some cases, the Version may indicate PWB or CRT differences
• This information is listed in the Main Difference List of the Service
Manual, or the Service Manual Supplements. For example YA319 is
the service manual, but YA319B would be a revision.
• The Example shows that the AV-32MF36 has (4) versions. The
example shows the “Z” Version of this model.
• The Model Number listed at the top of the model label will always be
the same for all versions.
• The TV Model Version is usually shown to the right of the Serial
Number on the Model Label

SERVICE MANUAL SUPPLEMENTS
TELEVISION
Picture tube of AV-48P776/H was changed.
Therefore, this service manual describes only the items which differ from those of the AV-48P776/H service manual.
For details other than those described in this manual, please refer to the AV-48P776/H service manual
(No.YA318, 2005/11).
No. YA318B
2006/6
Supplements show Corrections, Additions and Differences
that may have occurred during the production of a TV Model.
Service Manual Supplement
Original Service Manual

• Some Service Manual have Supplements
• Supplements show Corrections, Additions and Differences
that may have occurred during the production of a TV
Model.
• It is necessary to ensure you have all Service Documents
for a model prior to servicing.
• The Original Manual will only show the original Service
Information for a model, but Service Manual Supplements
may list information that is important to the service of a
model.
• Ensure that you use the Model and Model Version when
looking for documents on ISee to ensure you are getting
the correct information.

SWITCHING POWER SUPPLY
TELEVISION
LIVE ISOLATED
When troubleshooting it is
necessary to use the
respective ground of the
device you are measuring.
Taken from Schematic 52004 Main PWB

• This is the Power Section from the AV-32F703 taken from the 52004
Schematic of the Main PWB.
• On the schematic, there a BLACK line that separates the LIVE and
ISOLATED sides of the PWB. Components on the left side are live.
Those on the right side are isolated
• When troubleshooting it is NECESSARY to use the respective ground,
Live or Isolated, of the device you are measuring.
• Additional components, located along the dotted line, ensure circuit
isolation while passing all Power or Control signals. These
components are the Relay, Switching Transformer, Photocoupler and
the Capacitors that are used to connect the Live and Isolated grounds.

POWER SUPPLY COMPONENTS
TELEVISION
1. F901 and VA901 Surge Protection
2. T951, D954-57 and C951 Standby Power
3. C901, C902 and C903 Line Filter:
4. D901 and C907 Main rectifier
5. IC911 Switching Regulator
6. D911, R911,R930 and C914 Startup
7. T921 Switching Transformer
8. R912, R913 and R914 Current Feedback
9. R915 and D912 Run DC
10. D917 and D914 Refresh
11. D945 ~ RY951 Main Relay
12. Q951 Main Relay Drive
13. IC921 Error Amp
Schematic 52004 Main PWB

• Reference Schematic 52004 Main PWB for Schematic Details.
• This is a brief explanation of the components that make up the Power Supply and there functions.
• This is the basic circuit configuration and use for all JVC Power Supplies. While some Power
Supplies may omit or add circuits, the general function of all JVC Power Supplies are the
same.
1. F901 and VA901 Surge Protection: Stops circuit function if High Current (short) is detected.
2. T951, D954-57 and C951 Standby Power: Supplies Standby DC voltage to Micon
3. C901, C902 and C903 Line Filter: Filtering of AC line noise
4. D901 and C907 Main rectifier: Provides rectified DC to Switching Regulator and Switching
Transformer.
5. IC911 Switching Regulator: Regulates Switching Voltages out of Transformer
6. D911, R911,R930 and C914 Startup: Provides Startup DC for Switching Regulator until Transformer
conduction begins
7. T921 Switching Transformer: Provides voltages to all circuits
8. R912, R913 and R914 Current Feedback: Provides current feedback to Switching IC to stop
conduction.
9. R915 and D912 Run DC: Provides additional DC to Switching IC
10. D917 and D914 Refresh: Provide Refresh voltage to Restart IC Regulation
11. D945 ~ RY951 Main Relay: Allows Power flow to Switching IC and SW Reg. Also functions
as relay for Degauss
12. Q951 Main Relay Drive: Controls function of Main Relay
13. IC921 Error Amp: Monitors B1 Line Voltage

BASIC SWITCHING
INDUCTOR CHARGING
1. Switch SW1 off
2. Apply a DC to the inductor as
shown
3. Turn SW1 on and the Current
rises slowly
4. The Inductor charges to its
maximum
5. After charging is complete,
the current stays constant
TELEVISION

• One of the important part in SMPS is the Transformer. Transformer
functions like a basic inductor.
• With a DC applied to an inductor and connected to ground through a
resistor, if the switch is turned on, the current will rise slowly through
the inductor and the resistor.
• The current ramps up and Reaches maximum and stays constant.
• When the current does not change any more, the inductor is fully
charged.
• Capacitors and inductors behave similarly but opposite. Capacitors can
hold the charge, but inductors can not. It has to be discharged. If there
is no path to discharge, it will make eddy current through the coil and
produce heat.
• The basic of Switching power supply is the effective and controlled
use of using the discharged energy.

TELEVISION
HEAT
HEAT
Once the Inductor is finished charging,
turn SW1 off.
1. What happens to the charge in the
inductor? It will be lost as heat.
2. Can we use this energy? If so, how?
3. Can we control this charging? If so,
how?
This can be applied in the Switching
Power supply.
BASIC SWITCHING
INDUCTOR DISCHARGING

• When the current flow to the Fully Charged Inductor is
interrupted by closing SW1, the stored energy is released as
Heat.
• This stored energy is utilized in the Switching Power Supply.

TELEVISION
ENERGY If there is a secondary winding during
the off time, energy will be transferred
into the secondary.
In other words:
Transformer charges during ON-time.
Discharges during OFF-time
BASIC SWITCHING
TRANSFORMER OPERATION

If the coil has a secondary winding and a load is attached, it is called a transformer
because it transforms the energy into electrical energy and delivers it to a load.
In other words, the transformer discharges its stored energy into the secondary.
Repeating these actions again.
1. When the Switch is turned on the primary charges.
2. When the Switch is turned off, the charged core of the inductor discharges into the
secondary.
3. Since we are interested in DC output, the addition of the Diode and Capacitor at
the secondary will allow for the energy to be stored in the Capacitor. This stored
energy is our Secondary DC voltage.
4. If the switch is turned off prior to fully charging the inductor, the transferred
energy will be less. This shows that by controlling the Switch’s on/off time we can
obtain necessary secondary voltage.
The Transformer, Switch or any Switching Device and a Control Circuit (to
control on/off switching) make up a Switching Supply.

1. Apply an unregulated DC Voltage to the Transformer’s Primary.
2. Switching the Primary ON and OFF will result in Secondary Voltage.
3. Controlling the ON/OFF timing of the Switching Device will result in a
Regulated Secondary Voltage
Switching power supply regulation is achieved by controlling
the switching device’s ON/OFF timing .
TELEVISION BASIC SWITCHING
SUMMARY

SWITCHING DEVICE
• STR-Fxxxx IC
• Very reliable construction
• All in one package
• Protection circuits
• Minimum pins (5 pins)
GND
5
4
VCC
S
D
Ocp/
FB
OVP
TSD
OSC
DRV
STR-
F6xxxx
2
3
1
TELEVISION