Roland ME-50 Operating and maintenance manual

SERVICE NOTES
Issued by RJA
Copyright © 2003 ROLAND CORPORATION
All rights reserved. No part of this publication may be reproduced in any form without the written permission
of ROLAND CORPORATION.
Printed in Japan (0800) (AS)17058813E0
Feb.2003 ME-50
SPECIFICATIONS.............................................................2
LOCATION OF CONTROLS ..........................................4
LOCATION OF CONTROLS PARTS LIST ...................4
EXPLODED VIEW ............................................................6
EXPLODED VIEW PARTS LIST ..................................... 8
PARTS LIST......................................................................10
CHECKING THE VERSION NUMBER.......................13
RESTORING THE FACTORY SETTINGS...................13
TEST MODE.....................................................................13
BLOCK DIAGRAM.........................................................20
CIRCUIT BOARD............................................................22
CIRCUIT BOARD............................................................24
CIRCUIT DIAGRAM......................................................26
TABLE OF CONTENTS

2
Feb.2003
SPECIFICATIONS
ME-50: Guitar Multiple Effects
AD Conversion
24 bit + AF method (*)
DA Conversion
24 bit
Sampling Frequency
44.1 kHz
Patches
30 (user)
Effects
Tone Modify
Compressor
Overdrive/Distortion
Chorus
Phaser
Flanger
Harmonist
Tremolo
Pan
Vibrato
UNI-V
Rotary
Delay
Reverb
Noise Suppressor
(Effects for Expression Pedal)
Foot Volume
Wah
Resonance
Voice
Ring Modulator
Bend (+1 OCTAVE, -1 OCTAVE)
Nominal Input Level
INPUT: -10 dBu
AUX IN: -10 dBu
Input Impedance
INPUT: 1 M ohms
AUX IN: 100 k ohms
Nominal Output Level
-10 dBu
Output Impedance
2 k ohms
Display
7 segments, 1character LED
Jacks
INPUT jack
GUITAR AMP jacks L(MONO)/R
AUX IN jack (Stereo Mini type)
PHONES/LINE OUT jack
AC Adaptor jack
Power Supply
DC 9 V: Dry batteries (R6/LR6 (AA) type) x 6, AC Adaptor (PSA series:
Optional)
Current Draw
120 mA
* Expected battery life under continuous use:
Carbon: 3.5 hours
Alkaline: 12 hours
These figures will vary depending on the actual conditions of use.
Dimensions
384 (W) x 225 (D) x 102 (H) mm
15-1/8 (W) x 8-7/8 (D) x 4-1/16 (H) inches
Weight
3.15 kg / 7 lbs (including batteries)
Accessories
Owner’s Manual ENGLISH :(#G6017362)
JAPANESE :(#G6017361)
Dry Batteries (Alkaline: LR6 (AA) type) x 6:(#********)
Options
AC Adaptor: BOSS PSA series
Foot Switch: BOSS FS-5U
* 0 dBu = 0.775 Vrms
* In the interest of product improvement, the specifications and/or appearance of
this unit are subject to change without prior notice.
* AF method (Adaptive Focus method)
This is a proprietary method from Roland that vastly improves the signal-to-
noise (S/N) ratio of the A/D and D/A converters.

3
ME-50

5
Feb.2003 ME-50
LOCATION OF CONTROLS
fig.panel
1
2,4
3,4
1
5,6,18
2,4
3,4
1
7
8
910 11,4
13
12
14
15,16
17,18
19
20
2122
23
24
25
26 27 28
29
LOCATION OF CONTROLS PARTS LIST
NO PART CODE PART NAME DESCRIPTION
1 1502928100 LED (RED) L-34HDSL
2 F3279803 POTENTIOMETER 11 CLICKS 50KB RD901-40-125F-B54-11D
3 F3279802 POTENTIOMETERNO CLICK 50KB RD901-40-125F-B54-00D
4 G2477122 R-KNOB
5 F5029117 LED L-312LRD
6 G247751001 VGA KEYTOP S BLACK WITH LENS
7 G2027904 TOP COVER
8 G2187193 BOTTOM COVER
9 G2187602 SWITCH PEDAL
10 G2227301 PEDAL ESCUTCHEON
11 F3279804 POTENTIOMETER 6 CLICKS RD901-40-125F-B54-06D 50KB
12 G2187547 VR PEDAL
13 G2357125 PEDAL PLATE
14 15029106 LED LD002VB
15 G2047001 7SEG COVER
16 F5029408 LED A-601H
17 G247751301 VGA KEYTOP S WITHOUT LENS
18 F3129306 SWITCH SKQKAB
19 G1147002 REAR PANEL
20 13449155MF PHONE JACK (MONO) HTJ-064-12I
21 13449440 JACK HSJ0857-01-210
22 13449150MF PHONE JACK (STEREO) HTJ-064-12D
23 F3159111 SLIDE SW SK22F02
24 F3449717 JACK HEC2392-01-150
25 F2367103 CORD HOOK
26 G2217733 PEDAL LABEL (OD/DS)
27 G2217734 PEDAL LABEL (MOD)
28 G2217735 PEDAL LABEL (DELAY)
29 F3279782 POTENTIOMETER RK11K1140(10K SPECIAL B-CURVE)
NO PART CODE PART NAME DESCRIPTION

6
Feb.2003
EXPLODED VIEW
fig.explo1

7
ME-50
fig.explo2

8
Feb.2003
EXPLODED VIEW PARTS LIST
[PARTS]
[SCREWS]
NO PART CODE PART NAME DESCRIPTION
1 G2027904 TOP COVER
2 G2187193 BOTTOM COVER
3 G1147002 REAR PANEL
4 G2047001 7SEG COVER
5 G2187547 VR PEDAL
6 G2187910 PEDAL HOLDER
7 G2147119 BOLT HOLDER
8 G2357125 PEDAL PLATE
9 G2357122 REAR CUSHION
10 G2357111 CUSHION R
11 G2147806 STAY
12 G2217733 PEDAL LABEL (OD/DS)
13 G2217734 PEDAL LABEL (MOD)
14 G2217735 PEDAL LABEL (DELAY)
15 G2227301 PEDAL ESCUTCHEON
16 G2187602 SWITCH PEDAL
17 G2177103 SUPPORT SPRING
18 G2357126 PEDAL FOOT H=7.6
19 G247751001 VGA KEYTOP S BLACK WITH LENS
20 G247751301 VGA KEYTOP S WITHOUT LENS
21 G2477122 R-KNOB
22 F2367103 CORD HOOK
23 G2357120 FOOT H=5
24 G2017617 BATTERY CASE
25 G2027602 BATTERY COVER
26 G2177304 BATTERY TERMINAL (+ -)
27 G2177305 BATTERY TERMINAL (+)
28 G2177306 BATTERY TERMINAL (-)
29 75E013P000 MAIN SHEET ASSY
30 F3467025 WIRING 2P
MAIN SHEET ASSY includes the following parts.
31 ******** EXP BOARD ASSY
NO PART CODE PART NAME DESCRIPTION
a H5039521 VR ACCESSORY NUT M7
b H5039520 M9 NUT
c H5039126 M9 WASHER
d H5039514 NUT M6 HSJ-0999-01-190
e H5039121 WASHER 9.5X6.5 HSJ-0999-01-210
f H5039510 NUT M9X12X2 FENI
g H5039112 WASHER M9
h H5029331 SCREW 3X8 BINDING S-TIGHT FEBC
k H5029332 SCREW 3X6 BINDING S-TIGHT FEBZC
m H5029308 SCREW 3X10 BINDING S-TIGHT FEBC
n H5029330 SCREW M3X8 BINDING TAPTITE P BZC
o H5019124 SCREW M3X6 PAN MACHINE W/SW+SMALL PW ZC
p H5019130 SCREW M3X6 PAN MACHINE W/SW+PW ZC
q H5029867 HEX BOLT M6X70 HALF THEREAD BZ
r H5039122 PLAIN WASHER 6X13X1 BZC
s H5039515 NUT M6 U BZC
t H5019154 SPRING WASHER 6X12X1
u H5039111 PLAIN WASHER 3X8 ZC

9
ME-50

10
Feb.2003
PARTS LIST
fig.part1e
CASING
# G2047001 7SEG COVER 1
G2017617 BATTERY CASE 1
G2027602 BATTERY COVER 1
# G2187193 BOTTOM COVER 1
G2227301 PEDAL ESCUTCHEON 3
# G1147002 REAR PANEL 1
G2187602 SWITCH PEDAL 3
# G2027904 TOP COVER 1
# G2187547 VR PEDAL 1
CHASSIS
# G2187910 PEDAL HOLDER
# G2147806 STAY 1
KNOB,BUTTON
G2357120 FOOT H=5 4
# F2367103 CORD HOOK 1
G2477122 R-KNOB 20
G247751001 VGA KEYTOP S BLACK WITH LENS 1
G247751301 VGA KEYTOP S WITHOUT LENS 4
SWITCH
13129778 SKQKAH TACT SWITCH SW7,8,9 3
# F3129306 SKQKAB SWITCH SW1,2,3,4,6 5
# F3159111 SK22F02 SLIDE SW SW5 1
JACK,EXT TERMINAL
13449150MF HTJ-064-12D PHONE JACK (STEREO) JK6,4 2
13449155MF HTJ-064-12I PHONE JACK (MONO) JK1,2,3 3
# F3449717 HEC2392-01-150 JACK JK7 1
13449440 HSJ0857-01-210 JACK JK5 1
PWB ASSY
# 75E013P000 MAIN SHEET ASSY 1
IC
01672634 TC74HC4052AFT(EL) IC TTL IC4,7,10 3
15209102 M51957BFP IC (SYSTEM RESET) IC3 1
# F5199110 S-81233SGY IC (REGURATOR) IC19 1
# F5289101 NJM2100M 8P SOP IC (OP.AMP) IC2 1
# 03123889 HD6433687 IC (MASK CPU) IC11 1
# F5279309 BU2090F-E2 IC (LED DRIVER) IC16,17 2
# F5179607 CAT24WC32J IC (EEPROM) IC15 1
02231767 RA0A-101 (TC223C080AF-101) IC (DSP) IC8 1
# F5279520 LC32V4265T-25-TLM IC (DRAM) IC12 1
# 03123901 LT1616 IC (DC-DC) IC14 1
15189261 M5218AFP-600E IC (BIPOLAR OP AMP) IC1,5,18 3
01125012 NJM4556AM IC (BIPOLAR OP AMP) IC6 1
02451434 AK4552VT IC (AD/DA) IC3 1
TRANSISTOR
15309104 2SA1586-GR(TE85R) TRANSISTOR Q6 1
15319107 2SC4116-GR(TE85R) TRANSISTOR Q9 1
15319115 2SC4213-A(TE85L) TRANSISTOR Q2,3,4,5 4
15329103 2SK880GR-TE85R FET TRANSISTOR Q1 1
SAFETY PRECAUTIONS:
The parts marked have
safety-related characteristics. Use
only listed parts for replacement.
CONSIDERATION ON PARTS ORDRING
When ordering any parts listed in the parts list, please specify the following items in the order sheet.
QTY PART NUMBER DESCRIPTION MODEL NUMBER
Ex. 10 22575241 Sharp Key C-20/50
15 2247017300 Knob (orange) DAC-15D
Failure to completely fill the above items with correct number and description will result in delayed or even
undelivered replacement.
NOTE: The parts marked # are new. (initial parts)

11
ME-50
DIODE
1502928100 L-34HDSL LED (RED) LED2,3,6,79,10,11,12,13,14,15,16,17,19,20,21 16
15029106 LD002VB LED LED4,8 2
# F5029408 A-601H LED LED5 1
F5029117 L-312LRD LED LED18 1
15339119 1SS-352 DIODE D1,3,5,6 4
F5339137 SS14 VF=0.45V DIODE D4,7 2
RESISTOR
F5419707 CRN34101J RESISTOR ARRAY RA1,2,3,4,6 5
F5419705 CRN34103J RESISTOR ARRAY RA7,9 2
F5419726 CRN34473J RESISTOR ARRAY RA8,10,11 3
F5429366 15K OHM F RANK (1%) RESISTOR (CHIP) R79 1
# F5399914 6.8KF RESISTOR R82 1
F5399951 68(1/2W) CHIP RESISTOR R39,52 2
F2569127 MINISMDC075 POLY SWITCH R80 1
00566867 RPC05T 100 J MTL.FILM RESISTOR R33,70 2
00567023 RPC05T 101 J MTL.FILM RESISTOR R20,61,100 3
00567156 RPC05T 102 J MTL.FILM RESISTOR R9,10,26,27 4
00567289 RPC05T 103 J MTL.FILM RESISTOR R1,2,5,6,7,13,16,21,22,28,29,35,36,38,42,46, 30
00567412 RPC05T 104 J MTL.FILM RESISTOR R12,63 18
00567556 RPC05T 105 J MTL.FILM RESISTOR R12,R63 2
00567167 RPC05T 122 J MTL.FILM RESISTOR R101 1
00567290 RPC05T 123 J MTL.FILM RESISTOR R86,89 2
00567301 RPC05T 153 J MTL.FILM RESISTOR R4 1
00567190 RPC05T 222 J MTL.FILM RESISTOR R85 1
00567078 RPC05T 271 J MTL.FILM RESISTOR R102,103,104,105,106,107,108,109 8
00567334 RPC05T 273 J MTL.FILM RESISTOR R95,99 2
00567089 RPC05T 331 J MTL.FILM RESISTOR R122 1
00567345 RPC05T 333 J MTL.FILM RESISTOR R3,11,23,77,78,81,84,87,88,138,139,141,145,1 2
00566967 RPC05T 470 J MTL.FILM RESISTOR R83,91 2
00567112 RPC05T 471 J MTL.FILM RESISTOR R94,112 2
00567245 RPC05T 472 J MTL.FILM RESISTOR R17,32,44,56,58,59,140,142 8
00567378 RPC05T 473 J MTL.FILM RESISTOR R15,31,37,40,41,45,47,48,51,54,55,60,129,133 14
00567256 RPC05T 562 J MTL.FILM RESISTOR R127,131 2
00567134 RPC05T 681 J MTL.FILM RESISTOR R92,93,110,111,113,114,115,116,117,118,119,
1
16
F5429365 10K OHM F RANK (1%) CHIP RESISTOR R24 1
F5429386 150K F (1608TYPE) CHIP RESISTOR R18 1
POTENTIOMETER
F3279802 RD901-40-125F-B54-00D POTENTIOMETERNO CLICK 50KB VR3,4,6,7,8,10,11,12,13,14,15,18,19,20,21 15
F3279804 RD901-40-125F-B54-06D 50KB POTENTIOMETER 6 CLICKS VR2 1
F3279803 RD901-40-125F-B54-11D POTENTIOMETER 11 CLICKS 50KB VR5,9,16,17 4
# F3279782 RK11K1140(10K SPECIAL B-CURVE POTENTIOMETER VR1 1
CAPACITOR
F5349704 ECPU1C474MA5 0.47 MYLAR CAPACITOR (SUBMICRON) C4 1
F3629110 100U/16V (H=7MM) CHEMICAL CAPACITOR C5,28,39,54,76,85,107,108,111,113,117,119,12 19
F3629700 10U/16V (H=7MM) CHEMICAL CAPACITOR C2,9,10,11,12,16,19,20,22,23,24,25,31,42,49, 17
01674612 ECJ1VB1H103K CERAMIC CAPACITOR C116 1
# 01674501 ECJ1VB1H182K CERAMIC CAPACITOR C37,53 2
01674512 ECJ1VB1H222K CERAMIC CAPACITOR C1,7,14 3
01674712 ECJ1VF1A105Z CERAMIC CAPACITOR C130 1
01674701 ECJ1VF1E104Z 0.1UF/16VK CERAMIC CAPACITOR C18,26,29,30,32,34,38,45,46,47,48,59,60,61,6 58
01674167 ECUV1H100DCV CERAMIC CAPACITOR C3,8,21,35,36,51,52,128,129 9
01674467 ECUV1H102JCV CERAMIC CAPACITOR C95 1
01674189 ECUV1H120JCV CERAMIC CAPACITOR C100,101 2
01674356 ECUV1H151JCV CERAMIC CAPACITOR C44,58 2
# F3629708 0.22U/50 CAPACITOR C56,41 2
# F3629701 1/50 CAPACITOR C33 1
# F3629703 47/16 CAPACITOR C66 1
INDUCTOR,COIL,FILTER
F5409131 QT04-60 EMI L1 1
# F2449226 SLF7032T-100M 10UH COIL L3 1
CRYSTAL,RESONATOR
F5299306 HC-49SM 10.000MHZ CRYSTAL X1 1
02672401 SG-8002JC 67.7376MHZ PC CRYSTAL X2 1
CONNECTOR
F3439123 A2001WR2-3P CONNECTOR 3P CN2 1
F3439160 53015-0210 2P P=2MM CONNECTOR CN3 1

12
Feb.2003
WIRING,CABLE
# F3467025 WIRING 2P 1
# F3467024 WIRING 3P 1
SCREWS
H5039111 WASHER D8D3T0.5 ZC 2
# H5039515 NUT M6 U BZC 1
H5019124 SCREW M3X6 PAN MACHINE W/SW+SMALL PW ZC 8
H5019130 SCREW M3X6 PAN MACHINE W/SW+PW ZC 8
# H5039121 WASHER 9.5X6.5 HSJ-0999-01-210
# H5039514 NUT M6 HSJ-0999-01-190
# H5029867 HEX BOLT M6X70 HALF THEREAD BZ 1
H5039510 NUT M9X12X2 FENI for Phones Jack 5
# H5029330 SCREW M3X8 BINDING TAPTITE P BZC 6
H5029332 SCREW 3X6 BINDING S-TIGHT FEBZC 6
H5029308 SCREW 3X10 BINDING S-TIGHT FEBC 1
H5029331 SCREW 3X8 BINDING S-TIGHT FEBC 10
# H5039122 PLAIN WASHER 6X13X1 BZC 1
# H5019154 SPRING WASHER 6X12X1 1
G2147119 BOLT HOLDER 2
H5039520 M9 NUT with VR RK11K1140 1
H5039126 M9 WASHER 1
H5039521 VR ACCESSORY NUT M7 with VR RD901-40 20
H5039112 WASHER M9 for Phones Jack 5
PACKING
# G2627753 PACKING CASE 1
# G2267501 PAD L 1
# G2267502 PAD R 1
MISCELLANEOUS
# G2199505 LED SPACER LED-7A 15
# G2199506 LED SPACER LED-15A 3
# G2357126 PEDAL FOOT H=7.6 3
# G2217733 PEDAL LABEL (OD/DS) 1
# G2217734 PEDAL LABEL (MOD) 1
# G2217735 PEDAL LABEL (DELAY) 1
G2177304 BATTERY TERMINAL (+ -) 2
G2177305 BATTERY TERMINAL (+) 1
G2177306 BATTERY TERMINAL (-) 1
G2357111 CUSHION R 1
G2147127 DC JACK HOLDER 1
# G2357125 PEDAL PLATE 1
G2357122 REAR CUSHION 2
G2177103 SUPPORT SPRING 3
ACCESSORIES (Standard)
# G6017361 OWNER’S MANUAL JAPANESE
# G6017362 OWNER’S MANUAL ENGLISH 1
40232389 WARRANTY CARD FOR BOSS JAPAN ONLY

13
ME-50
CHECKING THE VERSION
NUMBER
•Device Settings
Turn the VR knobs (pots) completely to the left (minimum).
•Hold down the [EDIT/EXIT] switch and [WRITE] switch and turn the
POWER switch on.
Press the [FOOT 1] switch.
If the version number is Ver.1.01, the “b”(flat symbol) LED lights up, and “1”
appears in the seven-segment LED.
fig.test-4_70
RESTORING THE FACTORY
SETTINGS
•Hold down the [WRITE] switch and [ ] switch and turn the POWER
switch on.
“F”appears in the seven-segment LED.
•Press the [WRITE] switch. The BANK LED flashes.
•Press the [WRITE] switch. The seven-segment LED and BANK LED flash,
and the factory data is loaded.
The dot in the seven-segment portion lights, and Factory Reset is completed
when the unit switches to Play mode.
Never turn off the power while factory data is being loaded.
TEST MODE
Items to Have On Hand
Oscilloscope (1)
Oscillator (1)
Monitor amps (2)
Noise meters (2)
FS-5U (2)
Open plug
Measuring Equipment Settings
Oscillator
Waveform: Rectangular wave
Frequency: 400 Hz
Output Level: 50 mVp-p
Oscilloscope
TIME/DIV : 0.5 msec
VOLTS/DIV : 0.2 V
Noise Meter
Filter: IHF-A (JIS-A)
Foot Switch (FS-5U)
POLARITY SW: Jack
Switching into Test Mode
•Device Settings
Turn all VR knobs (pots) completely to the left (minimum).
fig.test-2_50
•Hold down the [EDIT/EXIT] switch and [WRITE] switch and turn the
POWER switch on.
Test Categories
1. LED Full Lighting, EEPROM Check
2. LED Lighting Check
3. Key SW, Pedal SW Check
4. External SW Check
5. VR Check
6. EXP Pedal Check
7. DSP Check
8. D/A Circuitry Check
9. DRAM Check
10. INPUT A/D Check, AUX IN Check, Noise Check
11. EXP Pedal Adjustment
Test Details
Switch to Test mode.
•Device Settings
Turn all VR knobs (pots) completely to the left (minimum).
•Hold down the [EDIT/EXIT] switch and [WRITE] switch and turn the
POWER switch on.
1. LED Full Lighting, EEPROM Check
•After the test is implemented, with data read from and written to the
EEPROM, all of the LEDs light up.
•Confirm the following.
1. All LEDS are lit.
2. No LED goes off when the unit is subjected to shock.

14
Feb.2003
fig.test-3_50
•With all LEDs lit, press the following switches to enable selection of the
type of check to start.
Press the [FOOT 1] switch to proceed to the “Version Check.”
Press the [FOOT 2] switch to proceed to “5. VR Check.”
Press the [FOOT 3] switch to proceed to “6. EXP Pedal Check.”
Press the [ ] switch to proceed to “7. DSP Check.”
Press the [ ] switch to proceed to “11. EXP Pedal Adjustment.”
•Version Check
Press the [FOOT 1] switch.
If the version number is Ver.1.01, the “b”(flat symbol) LED lights up, and “1”
appears in the seven-segment LED.
After confirming the version, press the [ ] switch to proceed to the LED
lighting check.
2. LED Lighting Check
•Confirm that the LEDs light up in sequence each the [WRITE] switch is
pressed.
fig.test-5_50
Sequence in Which LEDs Light Up
[TONE MODIFY]→[COMPRESSOR]→[NS]→[REVERB]→([b]−>[#])
→[TUNER]→[MEMORY]
→[EACH SEGMENT OF 7-SEGMENT LED]→[PEDAL MODE
SW]→[DELAY]→[MODULATION]
→[OVERDRIVE/DISTORTION VARIATION]→[FOOT 1]→[FOOT 2]→[FOOT
3]
→RETURN TO [TONE MODIFY]
•Press the [ ] switch to proceed to the next step.
Note: This will not advance the procedure to the next step unless the cycle has
returned to [TONE MODIFY].
3. Key SW, Pedal SW Check
•Press the following switches in the indicated sequence.
[WRITE]→[ ]→[EDIT/EXIT]→[ ]→[TYPE VARIATION]→[FOOT
1]→[FOOT 2]→[FOOT 3]
Note: If the incorrect key is pressed inadvertently, the procedure does not
advance to the next key unless the correct key is pressed twice.
fig.test-6_50
If no problem exists, the procedure automatically proceeds to the next step.
4. External SW Check
•Connect two FS-5U foot switches, one each to the [TONE MODIFY] and
[COMP ON/OFF] jacks.
Set the FS-5U POLARITY switches at the jacks.
fig.test-7_70
•Press the [TONE MODIFY] switch (FOOT SW = TIP).
If no problem exists, then “2”appears in the seven-segment display.
fig.test-8_70
•Press the [COMP ON/OFF] switch (FOOT SW = RING).
If no problem exists, the procedure automatically proceeds to the next step.
5. VR Check
The dot in the seven-segment LED appears when the VR is not at the minimum
position.
fig.test-9_70
(1) Notched VR Check
•Rotate the following VRs (pots) in the indicated sequence.
[TONE MODIFY]→[OVERDRIVE/
DISTORTION]→[MODULATION]→[DELAY]→[PEDAL MODE SW]
Note: The notched VRs turn in both directions (clockwise and
counterclockwise).
Note: Confirm that what is displayed in the seven-segment LED changes with
each notch position.
[TONE MODIFY], [OVERDRIVE/DISTORTION], [MODULATION], and
[DELAY] = “0”--”A”
123456789
10
11
12
13
14
15
16
17
18
19
20
234
12
56789
10
11
13
20
14
19
15
16
18
17
1
8
7
5
6
12
3
4

15
ME-50
[PEDAL MODE SW] = “0”--”5”
fig.test-10_50
(2) Non-Notched VR Check
•Rotate the following VRs (pots) in the indicated sequence.
[COMPRESSOR:SUSTAIN]→[COMPRESSOR:LEVEL]→[NS:THRESHOLD]→
[REVERB]→[MASTER LEVEL]→[OVERDRIVE/DISTORTION:DRIVE]→
[OVERDRIVE/DISTORTION:BOTTOM]→
[OVERDRIVE/DISTORTION:TONE]→
[OVERDRIVE/DISTORTION:LEVEL]→[MODULATION:RATE/KEY]→
[MODULATION:DEPTH/HARMONY]→
[MODULATION:E.LEVEL/RESONANCE]→
[DELAY:TIME]→[DELAY:FEEDBACK]→[DELAY:E.LEVEL]
Note: Confirm that what is displayed in the seven-segment LED changes with
each notch position.
fig.test-11_70
fig.test-12_70
fig.test-13_70
fig.test-14_50
If no problem exists, the procedure automatically proceeds to the next step.
6. EXP Pedal Check
•Start with the expression pedal in the depressed position.
•Carry out the following operations in the indicated sequence.
fig.test-15_70
1. Raise the tip of the expression pedal until it is at its highest point.
fig.test-16_70
2. Lower the tip of the expression pedal until it is approximately at the
midpoint.
fig.test-17_70
3. Once again, press down tip down completely so that the pedal is in the fully
depressed position.
fig.test-18_70
If no problem exists, the procedure automatically proceeds to the next step.
7. DSP Check
•The DSP check is performed automatically.
If no problem exists, the procedure automatically proceeds to the next step.
8. D/A Circuitry Check
fig.test-19_70
•Oscilloscope Settings: Ch1: 0.2 V/div; Ch2: 0.2 V/div; TIME: 0.5 ms/div
•Connect the cable only to the OUTPUT L(MONO) jack, then confirm that
the waveform output by OUTPUT L(MONO) changes accordingly, as
shown in the figures below.
1
2
345
12345
678910 11 12 13 14 15

16
Feb.2003
[Mute Off]
fig.test-20_50
[Mute On]
fig.test-21_50
•Next, connect the cable to OUTPUT R, then confirm that the waveform
output by OUTPUT R changes accordingly, as shown in the figures
below.
[Mute Off]
fig.test-22_50
[Mute On]
fig.test-21_50
•Disconnect the cable from OUTPUT R, then confirm that the waveform
output by OUTPUT L(MONO) changes accordingly, as shown in the
figures below.
[Mute Off]
fig.test-20_50
[Mute On]
fig.test-21_50
Reconnect the cable to OUTPUT R, then confirm that the waveform output by
OUTPUT changes accordingly, as shown in the figures below.
[Mute Off]
•Confirm that the value for the waveform amplitude is between 380 and
540 (mVp-p).

17
ME-50
fig.test-22_50
[Mute On]
fig.test-21_50
•Confirm that the LINE/PHONES waveform changes accordingly, as
shown in the figures below.
•Confirm that the value for the waveform amplitude is between 600 and
850 (mVp-p).
[Mute Off]
fig.test-23_50
[Mute On]
fig.test-24_50
Press the [ ] switch to proceed to the next step.
9. DRAM Check
fig.test-25_70
•Oscilloscope Settings: Ch1: 0.2 V/div; Ch2: 0.2 V/div; TIME: 0.5 ms/div
•Connect the cable only to the OUTPUT L(MONO) jack, then confirm that
the waveform from OUTPUT is smooth, as shown in the figure below.
•Confirm that the value for the waveform amplitude is between 330 and
470 (mVp-p).
fig.test-26_50
•Example of bad waveform: waveform is stepped

18
Feb.2003
fig.test-27_50
•Press the [ ] switch to proceed to the next step.
10. INPUT A/D Check, AUX IN Check,
Noise Check
fig.test-28_70
(1) INPUT A/D Check
Input a rectangular wave to the INPUT jack only, then check the waveform
from OUTPUT.
•INPUT Signal: 400-Hz, 50-mVp-p square wave
•Oscilloscope Settings: Ch1: 0.2 V/div; Ch2: 0.2 V/div; TIME: 0.5 ms/div
•Confirm that the value for the waveform amplitude is between 320 and
460 (mVp-p).
fig.test-29_50
(2) AUX IN Check
Input a rectangular wave to the AUX IN jack only, then check the waveform
from OUTPUT.
•INPUT Signal: 400-Hz, 200-mVp-p square wave
•Oscilloscope Settings: Ch1: 0.2 V/div; Ch2: 0.2 V/div; TIME: 0.5 ms/div
•Confirm that the value for the waveform amplitude is between 400 and
560 (mVp-p) GUITAR/AMP Jack.
fig.test-30_50
•Confirm that the LINE/PHONES waveform amplitude is between 290
and 410 (mVp-p).
(3) INPUT-to-OUTPUT Noise Check
•Disconnect cable connected to INPUT and AUX IN.
•Listen to the noise and confirm the following.
1. Noise level is -83.0 dBm IHF-A (JIS-A) or lower (both L and R).
2. No abnormal sounds are mixed with the output sound.
3. No abnormal sounds occur when the unit is subjected to shock.
•Press the [ ] switch to proceed to the next step.
11. EXP Pedal Adjustment
fig.test-31_70
fig.test-32_70
•Raise the unit’s expression pedal completely, release the pedal, and press
the [WRITE] switch.

19
ME-50
Note: Release the pedal when the pedal is fully raised, then press the [WRITE]
switch.
If an error occurs, the green LED in the upper portion of the seven-segment
LED display flashes.
fig.test-33_70
•Press the unit’s expression pedal completely forward, release the pedal,
and press the [WRITE] switch.
Note: Release the pedal when the pedal is pressed down completely, then
press the [WRITE] switch.
If an error occurs, the green LED in the upper portion of the seven-segment
LED display flashes.
fig.test-34_70
•Press the [ ] or [ ] switch to select “5,”then press the [WRITE]
switch.
•If no problem exists, the procedure automatically proceeds to Factory
Reset.
Factory Reset
“F”appears in the seven-segment LED.
•Press the [WRITE] switch. The BANK LED flashes.
•Press the [WRITE] switch. The seven-segment LED and BANK LED flash,
and the factory data is loaded.
The dot in the seven-segment portion lights, and Factory Reset is completed
when the unit switches to Play mode.
Never turn off the power while factory data is being loaded.
When the above is completed, the unit quits Test mode.

21
Feb.2003 ME-50
BLOCK DIAGRAM
fig.block
BUFFER
Q1
Pre Emph
Level CTL
IC2 CODEC
(AD/DA)
IC3
DE Emph
Level CTL
IC1
BUFFER
IC18
INPUT OUTPUT R
(MONO)
OUTPUT L
FILTER
IC5
MUTE
Q2,3
BUFFER
(NON INV)
IC6
PHONES/
LINE
DSP
IC8
DRAM
IC12
CPU
IC11
RESET
LED 2-4
LED 6-9
7 SEG
LED
LED DRIVER
IC16
LED 10-21
LED DRIVER
IC17
MUTE CONTROL
Q6
EEPROM IC
VR 18-21
VR 14-17
VR 10-13
VR 6-9
VR 2-5
ANALOG
MULTIPLEXER
IC4
ANALOG
MULTIPLEXER
IC10
ANALOG
MULTIPLEXER
IC7
EXP PEDAL
RIPPLE
FILTER
Q9
DC-DC
CONVERTER
IC14
+3.3V
FOR ANALOG
+9.0V
AUX IN
CRYSTAL
OSCILLATOR
X2
SW
1-4,6-9
CTL1,2
DC IN
VOLTAGE
REGULATOR
IC19
FOR IC2, IC3
BATTERY
CN3
MUTE
Q4,5
SW5
JK 7
JK 1
JK 5
JK 6
JK 2
JK 3
JK 4
CRYSTAL
OSCILLATOR
X1

23
Feb.2003 ME-50
CIRCUIT BOARD
comp.eps
View from components side