Sony cx bk 2 service manual

Page 2

CX-BK2

Notes on chip component replacement

I Never reuse a disconnected chip component.

I Notice that the minus side ofa tantalum capacitor may be dame
aged by heat.

Flexible Circuit Board Repairing

I Keep the temperature of the soldering iron around 270 C dur-
ing repairing.

I Do not touch the soldering iron on the same conductor of the
circuit board (within 3 times).

I Be careful not to apply force on the conductor when soldering
or unsoldering.

CAUTION

Use of controls or adjustments or performance of procedures
other than those specified herein may result in hazardous ra-
diation exposure.

The following caution label is located inside the unit.

This appliance is classified
cmssrmssn PRODucT as 3 CLASS I LASER

room I LASER one product.

KLASS 1 LASER APPARAT

This label is located on the
rear exterior.

UNLEADED SOLDER

Boards requiring use of unleaded solder are printed with the lead-

free mark (LF) indicating the solder contains no lead.

(Caution: Some printed circuit boards may not come printed with
the lead free mark due to their particular size)

s : LEAD FREE MARK

Unleaded solder has the following characteristics.

I Unleaded solder melts at a temperature about 40 C higher than
ordinary solder.
Ordinary soldering irons can be used but the iron tip has to be
applied to the solderjoint for a slightly longer time.
Soldering irons using a temperature regulator should be set to
about 350 C.
Caution: The printed pattern (copper foil) may peel away if the

heated tip is applied for too long, so be careful!

I Strong viscosity
Unleaded solder is more viscou-s (sticky, less prone to flow)
than ordinary solder so use caution not to let solder bridges oc-
cur such as on IC pins, etc.

I Usable with ordinary solder
It is best to use only unleaded solder but unleaded solder may
also be added to ordinary solder.

SAFETY CHECK-OUT

After correcting the original service problem, perfomr the follow-
ing safety check before releasing the set to the customer:

Check the antenna terminals, metal trim, metallized knobs,
screws, and all other exposed metal parts for AC leakage.

Check leakage as described below.

LEAKAGE TEST

The AC leakage from any exposed metal part to earth ground and

from all exposed metal parts to any exposed metal part having a

return to chassis, must not exceed 0.5 mA (500 microamperes.).

Leakage current can be measured by any one of three methods.

1. A commercial leakage tester, such as the Simpson 229 or RCA
WT-540A. Follow the manufacturers instructions to use these
instruments.

2. A batteryoperated AC milliammeter. The Data Precision 245
digital multimeter is suitable for this job.

3. Measuring the voltage drop across a resistor by means of a
VOM or battery-operated AC voltmeter. The limit indicaA
tion is 0.75 V, so analog meters must have an accurate low-
voltage scale. The Simpson 250 and Sanwa SH-63Trd are ex-
amples of a p' sive VOM that is suitable. Nearly all battery
operated digital multimeters that have a 2 V AC range are suit
able. (See Fig. A)

To Exposed Metal
Parts on Set

AC
0.15 F :' g 1.5 ko / voltmeter
(0.75 V)

_T- Earth Ground
Fig. A. Using an AC voltmeter to check AC leakage.

SAFETY-RELATED COMPONENT WARNING I!

COMPONENTS IDENTIFIED BY MARK A OR DOTTED
LINE WITH MARK A ON THE SCHEMATIC DIAGRAMS
AND IN THE PARTS LIST ARE CRITICAL TO SAFE
OPERATION. REPLACE THESE COMPONENTS WITH
SONY PARTS WHOSE PART NUMBERS APPEAR AS
SHOWN IN THIS MANUAL OR IN SUPPLEMENTS PUB-
LISHED BY SONY.