HCD-GTR88, MHC-GTR88 - Sony Audio Service Manual (repair manual)

2012E08-1

© 

2012.05

•  HCD-GTR88 is the amplifi er, USB, CD player, 

tuner and tape deck (only E4 Model) section in 
MHC-GTR88.

Photo: HCD-GTR88 (E4 Model)

CD Section

Model Name Using Similar Mechanism

HCD-GTZ4/GTZ4i/GTZ5

CD Mechanism Type

CDM88BL-DVBU101

Optical Pick-up Name

KHM-313CAB/C2NP

Tape Deck Section
(only for E4 Model)

Model Name Using Similar Mechanism

HCD-GT111/GT222/GT444/GT555

Tape Mechanism Type

CS-21SC-900TP

The following are measured at
Mexican model:
 

AC 127 V, 60 Hz 

Other models:
 

AC 120 V, 220 V, 240 V, 50/60 Hz

Front/Satellite Speaker
 

Power Output (rated):

 

200 W + 200 W (at 6 Ω, 1 kHz, 

 1% 

THD)

Front Speaker
 

RMS output power (reference):

 

345 W + 345 W (per channel at 8 Ω, 

 1 

kHz)

Satellite Speaker
 

RMS output power (reference):

 

140 W + 140 W (per channel at 24 Ω, 

 1 

kHz)

Subwoofer
 

RMS output power (reference):

 

200 W + 200 W (per channel at 6 Ω, 

 100 

Hz)

PC (AUDIO IN) L/R
 

Voltage 700 mV, impedance 47 kilohms

MIC
 

Sensitivity 1 mV, impedance 10 kilohms

 (USB) port: Type A

Outputs
PHONES
 

Accepts headphones of 8 Ω or more

USB section
Supported bit rate
 

MP3 (MPEG 1 Audio Layer-3):

 

32 kbps – 320 kbps, VBR

 

WMA: 48 kbps – 192 kbps

 

AAC: 48 kbps – 320 kbps

Sampling frequencies
 

MP3 (MPEG 1 Audio Layer-3):

 

32 kHz/44.1 kHz/48 kHz

 

WMA: 44.1 kHz

 

AAC: 44.1 kHz

Transfer speed
 Full-Speed
Supported USB device
 

Mass Storage Class

Maximum current
 500 

mA

System
 

Compact disc and digital audio system

Laser Diode Properties
 

Emission Duration: Continuous

 

Laser Output*: Less than 44.6 μW

 

* This output is the value measurement 

at a distance of 200 mm from the 
objective lens surface on the Optical 
Pick-up Block with 7 mm aperture.

Frequency response
 

20 Hz – 20 kHz

Signal-to-noise ratio
 

More than 90 dB

Dynamic range
 

More than 88 dB

Recording system
 

4-track 2 channel, stereo

Tuner section
FM stereo, FM/AM superheterodyne tuner
FM tuner section
Tuning range
 

North American and Brazilian models:

 

87.5 MHz – 108.0 MHz (100 kHz step)

 Other 

models:

 

87.5 MHz – 108.0 MHz (50 kHz step)

Antenna
 

FM lead antenna

Antenna terminals
 

75 ohms unbalanced

Intermediate frequency
 10.7 

MHz

Tuning range
 

Pan American and Oceanian models:

 

530 kHz – 1,710 kHz (with 10 kHz tun-
ing interval)

 

531 kHz – 1,710 kHz (with 9 kHz tuning 
interval)

 Other 

models:

 

530 kHz – 1,610 kHz (with 10 kHz tun-
ing interval)

 

531 kHz – 1,602 kHz (with 9 kHz tuning 
interval)

Antenna
 

AM loop antenna, external antenna 
terminal

Intermediate frequency
 450 

kHz

Power requirements
 

Oceanian model: AC 230 V – 240 V, 
50/60 Hz
Mexican model: AC 127 V, 60 Hz
Argentina model: AC 220 V, 50/60 Hz
Other models: AC 120 V, 220 V or 
230 V – 240 V, 50/60 Hz, Adjustable 
with voltage selector

Power consumption: 460 W
Dimensions (w/h/d) (excl. speakers)
(Approx.)
 

231 mm × 361 mm × 518 mm

Mass (excl. speakers) (Approx.)
 

African and Pan Asian models: 16.2 kg

 

Other models: 15.7 kg

Design and specifi cations are subject to 
change without notice.

• Abbreviation

E4 : African model

NOTES  ON  CHIP  COMPONENT  REPLACEMENT
•  Never reuse a disconnected chip component.
•  Notice that the minus side of a tantalum capacitor may be dam-

aged by heat.

FLEXIBLE  CIRCUIT  BOARD  REPAIRING
•  Keep the temperature of soldering iron around 270 °C during repairing.
•  Do not touch the soldering iron on the same conductor of the circuit 

board (within 3 times).

•  Be careful not to apply force on the conductor when soldering or unsol-

dering.

COMPONENTS  IDENTIFIED  BY  MARK  0  OR  DOTTED  LINE  
WITH  MARK  0  ON  THE  SCHEMATIC  DIAGRAMS  AND  IN  
THE  PARTS  LIST  ARE  CRITICAL  TO  SAFE  OPERATION.
REPLACE  THESE  COMPONENTS  WITH  SONY  PARTS 

CAUTION
Use of controls or adjustments or performance of procedures 
other than those specifi ed herein may result in hazardous radia-
tion exposure.

SAFETY  CHECK-OUT
After correcting the original service problem, perform the following safe-
ty 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 instru-
ments.

2.  A battery-operated 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” indication is 0.75 V, so 
analog meters must have an accurate low-voltage scale. The Simpson 
250 and Sanwa SH-63Trd are examples of a passive VOM that is 
suitable. Nearly all battery operated digital multimeters that have a 2 
V AC range are suitable. (See Fig. A)

This appliance is classified as a CLASS 1 
LASER product. This marking is located on 
the rear exterior.

 ..............................................   3

2-1. Disassembly 

Flow 

...........................................................   5

2-2. Case 

(Side-L/R) 

..............................................................   6

2-3. Top 

Case..........................................................................   6

2-4.  Tape Mechanism Deck (For African Model only) ..........   7
2-5.  Front Panel Block, HUB Board, DMB19 Board ............   7
2-6.  DC Fan (M101) ...............................................................   8
2-7.  Back Panel, SUBTRANS Board .....................................   8
2-8.  MAIN  Board ..................................................................   9
2-9.  DC Fan (M101), PT SHIELD Board, 

POWER AMP Board Section .........................................   9

2-10.  POWER AMP Board, SUBWOOFER Board .................   10
2-11. Chassis Section ...............................................................  10
2-12.  CD Mechanism Block (CDM88BL-DVBU101) ............   11
2-13.  Optical Pick-up Block (KHM-313CAB) ........................   11
2-14. Belt (DLM3A) ................................................................   12

 .............................................................   13

 .......................   15

 .........................   16

6-1.  Block Diagram - RF SERVO, USB Section - .................   17
6-2.  Block Diagram - MAIN Section - ...................................   18
6-3.  Block Diagram - AMP Section - .....................................   19
6-4.  Block Diagram - DISPLAY, 

POWER SUPPLY Section - ............................................   20

6-5.  Printed Wiring Board - DISPLAY Board - .....................   22
6-6.  Schematic Diagram - DISPLAY Board - ........................   23
6-7.  Printed Wiring Board - DMB19 Board - ........................   24
6-8.  Schematic Diagram - DMB19 Board (1/3) - ..................   25
6-9.  Schematic Diagram - DMB19 Board (2/3) - ..................   26
6-10.  Schematic Diagram - DMB19 Board (3/3) - ..................   27
6-11.  Printed Wiring Board - POWER AMP Board - ..............   28
6-12.  Schematic Diagram - POWER AMP Board - .................   29
6-13.  Printed Wiring Board - MAIN Board - ...........................   30
6-14.  Schematic Diagram - MAIN Board (1/3) - .....................   31
6-15.  Schematic Diagram - MAIN Board (2/3) - .....................   32
6-16.  Schematic Diagram - MAIN Board (3/3) - .....................   33
6-17.  Printed Wiring Board - MIC, VOL and USB Board - ....   34
6-18.  Schematic Diagram - MIC, VOL and USB Boards - ......   35
6-19.  Printed Wiring Board - TC Board - .................................   36
6-20.  Schematic Diagram - TC Board - ...................................   36
6-21. Printed Wiring Board 

- TRANS and SUBTRANS Board - ...............................   37

6-22. Schematic Diagram 

- TRANS and SUBTRANS Boards - ..............................   38

6-23.  Printed Wiring Board - SUBWOOFER Board - .............   39
6-24.  Schematic Diagram - SUBWOOFER Board - ................   40
6-25.  Printed Wiring Board - HUB Board - .............................   41
6-26.  Schematic Diagram - HUB Board - ................................   42

7-1. Case 

Section 

....................................................................  53

7-2.  Top Panel Section ...........................................................   54
7-3.  Loading Panel Section, HUB Board Section, 

DMB19 Board Section ....................................................   55

7-4.  DISPLAY  Board Section ...............................................   56
7-5.  Front Panel Section .........................................................   57
7-6.  Back Panel Section .........................................................   58
7-7.  MAIN  Board Section .....................................................   59
7-8. Chassis 

Section 

...............................................................  60

7-9.  CD  Mechanism Section (CDM88BL-DVBU101) .........   61

 ...............................   62

The laser diode in the optical pick-up block may suffer electro-
static break-down because of the potential difference generated by 
the charged electrostatic load, etc. on clothing and the human body.
During repair, pay attention to electrostatic break-down and also 
use the procedure in the printed matter which is included in the 
repair parts.
The fl exible board is easily damaged and should be handled with 
care.

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)

Unleaded solder has the following characteristics.
•  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 solder joint 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!

• Strong 

viscosity

 

Unleaded solder is more viscous (sticky, less prone to fl ow) 
than ordinary solder so use caution not to let solder bridges 
occur such as on IC pins, etc.

•  Usable with ordinary solder
 

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

NOTE  OF  REPLACING  THE  IC102  ON  THE  DMB19  
BOARD
IC102 on the DMB19 board cannot exchange with single. When 
this part is damaged, exchange the entire mounted board.

RELEASING  THE  DISC  TRAY  LOCK
The disc tray lock function for the antitheft of an demonstration 
disc in the store is equipped.

Releasing Procedure:
1. Press 

[I/

1

 STANDBY] button to turn the power on.

2.  Press the [CD] button to select CD function.
3.  While pressing the [

x

] button, press the [

Z

 OPEN/CLOSE] 

button for more 5 seconds).

4.  The message “UNLOCKED” is displayed and the disc tray is 

unlocked.

Note: When 

“

LOCKED

”

 is displayed, the slot lock is not released by 

turning power on/off with the

 [I/

1

 STANDBY]

 button.

• Abbreviation
 AR  : 

Argentina 

model

 AUS : 

Australian 

model

  E2 

: 120V AC area in E model

 E4  : 

African 

model

 E51  : 

Chilean and Peruvian models 

MX 

: Mexican model

HCD-GTR88: E2, E51

4-164-385-0[]

HCD-GTR88: AR

4-164-385-1[]

HCD-GTR88: MX

4-164-385-2[]

HCD-GTR88: E4

4-164-385-4[]

HCD-GTR88: AUS

4-164-385-5[]

NOTES  ON  LASER DIODE  EMISSION  CHECK
The laser beam on this model is concentrated so as to be focused 
on the disc refl ective surface by the objective lens in the optical 
pickup block. Therefore, when checking the laser diode emission, 
observe from more than 30 cm away from the objective lens.

Two kinds of tape mechanism decks installed by this set exist.

Please do the repair exchange after confi rming which tape mechanism deck 
set of the repair according to how to distinguish the fi gure below.

CS-21SC-900TP

1-797-575-11

2-688-621-01 BELT 
(R/F)
2-688-622-01 BELT 
(MAIN)

Step: 1) Work after removing the case (side-R and side-L) referring to “2.2. CASE (SIDE-L/R)” on disassembly (page 6).
 

  2)  Work after removing the top case referring to “2-3. TOP CASE” on disassembly (page 6).

d

a

c

c

b

e

When installing a new OP unit, be sure to connect the fl exible printed circuit board fi rst of all before removing the static electricity
prevention solder bridge by unsoldering.
Remove the static electricity prevention solder bridge by unsoldering after the fl exible printed circuit board has already been connected.
(Do not remove nor unsolder the solder bridge as long as the OP unit is kept standalone.)