Philips N4520, N4522 Quick Reference Guide

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 1/11

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PRO AUDIO AFFAIRS

Quick Reference Guide of Philips N4520 & N4522:

Page:

2 Layout of front panel N452X

Position of boards

3 Start of N4520 section

4 Layout of Panel 1 (audio undertray) with

short calibration instructions

5 Layout of Panel 1 (audio undertray) with location of

transistors

6 Overview of electrolitic capacitors, transistors

and pots lists for replacement

7 Start of N4522 section

8 Layout of Panel 1 (audio undertray) with

short calibration instructions

9 Layout of Panel 1 (audio undertray) with location of

transistors

10 Overview of electrolitic capacitors, transistors

and pots lists for replacement

This document is still under construction!!

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 2/11

line mic

balance

level

Master recording volume

winding speed

bias

level

phones

balance

line mic
line din
line din

source
auto
tape/cue

nab
iec3819

9,5

on
off

1-4
stereo

input

3-2

monitor

EQ

speed

sound-on-sound

track

VU Peak

N452X front panel

Layout of front panel N452X:

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 3/11

Position of boards N452X:

# description

1 audio main board
2A opto-print
2B rec/pb amp L/R
2C oscillator
3A headphone amp
3B pre amp
4A winding speed pot
4B cue buttons
4C control
4D motor control
5A counter
5B power supply
5C capstan motor
5D indicator
6 tension control L/R
7 power supply

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 4/11

From here on:

Philips N4520

(not N4522)

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 5/11

Calibrating N4520, short summary (always have the Service Manual at hand for the full instructions)
===================================================================================================

1 - section 3.2 impossible to perform (zero-setting peaklevel and VU meters).
2 - azimuth playback head. screw C.
3 - azimuth record head, insert conn. J into L, and conn. I into K. Adjust screw C rec head. reseat conn. (section 7)
4 - play ref tape 250 nWb/m – 0 dB section, line out: 780 mV. adjust R(1)27.
5 - play freq char. section, line output: make 1 kHz equivalent to 16 kHz ±1,5 dB. 1 kHz=ref.point. adjust R(1)57.
6 - record 9,5 cm/s BU5 (3,5) 330 Hz 1 V in. line out: 1 V ±0,25 dB. note LINE LEVEL position – LEAVE IT!
7 - record BU5 (3,5) 1 kHz 80 mV, 16 kHz 80 mV in. line out: 1 kHz=16 kHz ±2 dB. adjust R(1)36 bias.
8 - record freq sweep 31 Hz-16 kHz. line out: ±2 dB. 1 kHz=ref.point 0 dB
9 - record 330 Hz, adjust input signal so line out=1.41 V (meters +3 dB). distortion <3%. adjust R(1)36. repeat sweep.
10 - record BU5 (3,5) 330 Hz 1,41 V. line out: 1,41 V ±0,25 dB. adjust R(1)25 rec current.
11 - record 19 cm/s(!) BU5 (3,5) 1 kHz 80 mV, 20 kHz 80 mV in. line out: 1 kHz=20 kHz ±2 dB. R41 bias 19cm.
12 - record freq sweep 31 Hz-20 kHz(!). line out: ±2 dB. 1 kHz=ref.point 0 dB
13 - record 330 Hz, adjust input signal so line out=1.41V (meters +3dB). distortion <3%. adjust R41. repeat sweep.
14 - record 38 cm/s(!) BU5 (3,5) 1 kHz 80 mV, 26 kHz(!) 80 mV in. line out: 1 kHz=26 kHz ±2 dB. R40 bias 38 cm.
15 - record freq sweep 31 Hz-26 kHz(!). line out: ± 2dB. 1 kHz=ref.point 0 dB
16 - record 330 Hz, adjust input signal so line out=1.41 V (meters +3 dB). distortion <3%. adjust R40. repeat sweep.

BU104

(R)

BU4

(L)

BU106

(R)

BU6

(L)

2

4

1

6

7

5

3

R45

(L)

R145

(R)

R125

(R)

R25

(L)

Rec current

Line out

Line outLine in

Headphone Amp. (3A)

Headphone Amp. (3A)

Rec./PB. Amp. (2B)

Rec./PB. Amp. (2B)

Rec./PB. Amp. (2B)

Rec./PB. Amp. (2B)

Pre-amp (3B)

Pre-amp (3B)

R L

R36 (L)

R136 (R)

Bias 9,5 cm/s

Bias

R41

bias 19

cm/s

R40

bias 38

cm/s

Playback level

R27 (L)

R127

(R)

16 kHz 9,5 cm

Freq. characteristic

R157

(R)

R57 (L)

BU 5

Layout panel 1 Philips N4520

Oscillator (2C)

Oscillator (2C)

Philip van der Matten
www.reeltoreel.nl

J

I

L

K

r

e

c

/

p

b

h

e

a

d

A

B

C

Head assembly

screws

conn.

Head layout

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Layout of transistors & potentiometers on Panel 1 N4520:

This page not complete yet

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 7/11

audio panel 1 |record/playback PCBs 2B| headphone 3A panel 3B

left right

total:

caps

capacity in µF: V

0,47 63 9 2 7

1 63 4 2 1 1
1,5 63 2 2
3,3 63 2 2
4,7 63 21 6 5 5 5
6,8 40 2 2

15 40 8 2 2 2 2
22 25 13 2 2 2 7

47 10 4 2 1 1
100 25 1 1
150 16 2 2
220 25 2 1 1

total caps: 70 17 12 12 10 19

transistors

BC327/25 2 2
BC337/25 2 2
BC546A 2 2
BC547 1 1
BC547C 2 2
BC548 8 4 4
BC548C 10 3 3 4
BC549 2 2
BC549B 6 6
BC550B 2 1 1
BC556A 2 2
BC557 1 1
BC558 4 2 2
BC558B 4 4
BD135 ?
BF245A 7 7

total transistors 55 19 6 6 14 10

var. resistors/pots:

R(1)36 100kΩ R(1)25 22k
R(1)57 470kΩ R(1)45 10k
R(1)27 22kΩ checken
R40 47kΩ
R41 100kΩ

Philips N4520 components list

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 8/11

From here on:

Philips N4522

(not N4520)

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 9/11

Calibrating N4520, short summary (always have the Service Manual at hand for the full instructions)
===================================================================================================

1 - section 3.2 impossible to perform (zero-setting peaklevel and VU meters).
2 - azimuth playback head. screw C.
3 - azimuth record head, insert conn. J into L, and conn. I into K. Adjust screw C rec head. reseat conn. (section 7)
4 - play ref tape 250 nWb/m – 0 dB section, line out: 780 mV. adjust R(1)27.
5 - play freq char. section, line output: make 1 kHz equivalent to 16 kHz ±1,5 dB. 1 kHz=ref.point. adjust R(1)57.
6 - record 9,5 cm/s BU5 (3,5) 330 Hz 1 V in. line out: 1 V ±0,25 dB. note LINE LEVEL position – LEAVE IT!
7 - record BU5 (3,5) 1 kHz 80 mV, 16 kHz 80 mV in. line out: 1 kHz=16 kHz ±2 dB. adjust R(1)36 bias.
8 - record freq sweep 31 Hz-16 kHz. line out: ±2 dB. 1 kHz=ref.point 0 dB
9 - record 330 Hz, adjust input signal so line out=1.41 V (meters +3 dB). distortion <3%. adjust R(1)36. repeat sweep.
10 - record BU5 (3,5) 330 Hz 1,41 V. line out: 1,41 V ±0,25 dB. adjust R(1)25 rec current.
11 - record 19 cm/s(!) BU5 (3,5) 1 kHz 80 mV, 20 kHz 80 mV in. line out: 1 kHz=20 kHz ±2 dB. R41 bias 19cm.
12 - record freq sweep 31 Hz-20 kHz(!). line out: ±2 dB. 1 kHz=ref.point 0 dB
13 - record 330 Hz, adjust input signal so line out=1.41V (meters +3dB). distortion <3%. adjust R41. repeat sweep.
14 - record 38 cm/s(!) BU5 (3,5) 1 kHz 80 mV, 26 kHz(!) 80 mV in. line out: 1 kHz=26 kHz ±2 dB. R40 bias 38 cm.
15 - record freq sweep 31 Hz-26 kHz(!). line out: ± 2dB. 1 kHz=ref.point 0 dB
16 - record 330 Hz, adjust input signal so line out=1.41 V (meters +3 dB). distortion <3%. adjust R40. repeat sweep.

BU104

(R)

BU4

(L)

BU106

(R)

BU6

(L)

2

4

1

6

7

5

3

R45

(L)

R145

(R)

R125

(R)

R25

(L)

Rec current

Line out

Line outLine in

Headphone Amp. (3A)

Headphone Amp. (3A)

Rec./PB. Amp. (2B)

Rec./PB. Amp. (2B)

Rec./PB. Amp. (2B)

Rec./PB. Amp. (2B)

Pre-amp (3B)

Pre-amp (3B)

R L

R36 (L)

R136 (R)

Bias 9,5 cm/s

Bias

R41

bias 19

cm/s

R40

bias 38

cm/s

Playback level

R27 (L)

R127

(R)

16 kHz 9,5 cm

Freq. characteristic

R157

(R)

R57 (L)

BU 5

Layout panel 1 Philips N4522

Oscillator (2C)

Oscillator (2C)

Philip van der Matten
www.reeltoreel.nl

J

I

L

K

r

e

c

/

p

b

h

e

a

d

A

B

C

Head assembly

screws

conn.

Head layout

N

O

T

C

O

R

R

E

C

T

Y

E

T

!

!

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 10/11

Layout of transistors & potentiometers on Panel 1 N4522:

BF245

R36

R136

R57

R27

R41

R40

R157

R127

R145 R45

R125 R25

BF245BF245

BF245

BC548

BC556A

BC556A

BC546A

(4x)

Pots:
R(1)36 22 kΩ
R(1)27 22 kΩ
R(1)57 47 kΩ
R40 47 kΩ
R41 100 kΩ
R(1)25 22 kΩ

BC546B

BC557

BF245

BC548

BC546B

www.reeltoreel.nl Philip van der Matten ver 4.0 | 24 apr 2024 | page 11/11

audio panel 1 |record/playback PCBs 2B| headphone 3A panel 3B

left right

total:

caps

capacity in µF: V

0,47 63 9 2 7

1 63 4 2 1 1
1,5 63 2 2
3,3 63 2 2
4,7 63 21 6 5 5 5
6,8 40 2 2

15 40 8 2 2 2 2
22 25 13 2 2 2 7

47 10 4 2 1 1
100 25 1 1
150 16 2 2
220 25 2 1 1

total caps: 70 17 12 12 10 19

transistors

BC327/25 2 2
BC337/25 2 2
BC546A 2 2
BC547 1 1
BC547C 2 2
BC548 8 4 4
BC548C 10 3 3 4
BC549 2 2
BC549B 6 6
BC550B 2 1 1
BC556A 2 2
BC557 1 1
BC558 4 2 2
BC558B 4 4
BD135 ?
BF245A 7 7

total transistors 55 19 6 6 14 10

var. resistors/pots:

R(1)36 22 kΩ R(1)25 22 kΩ
R(1)57 470 kΩ R(1)45 10 kΩ
R(1)27 22 kΩ
R40 47 kΩ this table is still to be checked
R41 100 kΩ

Philips N4522 components list