Crown D-150 User manual

D-150
SM-5
$1P1-21-0
crown |
SERIAL NO.
ISSUED TO
SERVICE MANUAL
D-150
DUAL: CHANNEL
POWER AMPLIFIER
~ Div. of INTERNATIONAL RADIO & ELECTRONICS CORP. BOX 1000 ELKHART, INDIANA 46514 |

Se
ome
TABLE OF CONTENTS
SECTION
i INTRODUCTION
11
1.2
3 INSTALLATION AND OPERATION
4 CIRCUIT DESCRIPTION
41
5 SERVICE PROCEDURES
5.1
5.2
5.3
54
55
5.6
5.7
5.8
Scope of Manual
Equipment Description .
General ....
Unpacking ...
Mounting Instructions
Accessory Panel Kit Installation
Amplifier Protection. Mechanisms
Load Protection Methods
Operating Precautions ...
Connecting Output Lines
Connecting.Input-Lines .
Connecting Power ..
Operating Controls’.
Normal-Hi-Fi Installation
Cleaning. ...
Principles of Operation
introduction .....
Service Policies
Warranty...........
Disassembly for Servicing .
5.4.1. Removal of Bottom Cover, Transformer Cover and Wrap-around,
and Board and Electronics Cover -
5.42 Removal of Control Plate Assembly...
5.4.3 Replacement of Components-of Main PC-Board, 7891
5.4.4 Replacement of Input Level Potentiometers (R101, R201)
5.4.5 Replacement of Thermal Switch; SW-L..
5.4.6 Replacement of Bridge, DM-1 -....
5.4.7 Replacement of Filter Capacitors, C23 and C24
5.4.8 ...Replacement of Output-indactors;-L.102.and k202 ..
5.4.3 Replacement.of Driver and Output. Transistors
5.4.10 Replacervent of Power Transformer, 11 .
Test Equipment 000.0...
5.5.1 Calibration of Test Equipme:
Test Procedures.
Troubleshooting
5.7.1 Turr-on Procedure .
5.7.2 Qutput Offset Voltage Check .
5.7.3 Bias Level Check 0.
5.7.4 Checkout Procedure ~ 1 KHz Input, No Load .
5.7.5. Checkout Procedure — J KM2 Input; With Load
5.7.6 Checkout Procedure — Protection Circuit Tests
5.7.7 . Checkout Procedure — 20.KHz Sine Wave Input.
§.7.8 Checkout Procedure — 10 KHz Square Wave input .....
5.7.9. Checkout Procedure — IM intermodulation) Distortion Test -
5.7.10 Checkout Procedure ~ 20-20 KHz. Hunvand.Noise Test ....
5.7.11 Checkout Procedure — Quiescent AG Power Consumption
Bias Level Check and Adjustment

8 SCHEMATICS, PARTS LISTS AND COMPONENT LOCATION
6.1 General Information ...
6.2 Parts Replacernent .....
7 APPLICATION NOTES
7.1 General .. ae
Note 1. v-l Needs of 2 Load -
Note 2. D-150 Morio Conversion ..
Note 3. PA Adapter Panel installation .
LIST OF ILLUSTRATIONS
DESCRIPTION
integrated: Circuit. Stereo. D-150 Amplifier
D-150. Mountinig Dimensions’...
Panel Kit Mounting
Graph. of V-1 Operating Range, D-150 Output ..
Fuse Selector Nomiag for Loudspeaker Protection:
Relay-Controlied. Protector With Overload Indicator
Peak: Power Limiting Compressor With Qverdiive Indicator...
Turn-On-Transient Muter for Load Protection .
Rear View of Chassis .
Seheniatic tor-Full. Benge. Bectrostatic Speaker Connection
Schernatic of Ear Phone Pad .. aie
Cw OAD Nw om Oo
Source Resistance and Damping Factor ¥ vs. Length and ‘Size of Output Leads. . . 10
Graph for Selection of input Capacitor . 16
Low-Pass Filters for Severe RF at Inputs .. li
Line Voltage Connections (240 VAC) ~AL
Operating
Contrels
JL
Typical Hi-Fi Installation ....0..- 12
Test Equipment Complement es
Typical Protection Clipping, 2-Ohm Load . 26
Typical 20 KHz Sine Wave Test Output Waveform . . 26
Typical 10 KHz Square Wave Test Output Waveform . . 26
Bias Level Check Components.....: 27
Schernatic Diagrarn, 0-150 Ampiitier . 34
Explodéd View, 0-150 Chassis Assanibly 33-34
Component Location; D150 Main. PC Board 7891
Exploded View, Contfal Plate Assembiy’ ...
Exploded View, Output Inductor Assembly.

FIGURE 1-4,
INTEGRATED CIRCUIT STEREQ
2-150 AMPLIFIER
1.1 ‘SCOPE OF MANUAL
This matidal is intended to provide the User and sérvice tech-
nician necessary technical information required to install, oper-
ate and repair the CROWN D-150 Dual-Charnel Power Amplifier
properly and to maintain the unit in optirmum operating condition.
The manual is. comprehensive; containing a physical description
of the.0-150, electrical and mechanical specifications, complete
installation atid operating instructions, a detailed circuit descrip-
tion and service procedures to include troubleshooting and repair.
Also. included are.complete parts lists,.a unit schematic and.ex-
ploded view drawings to assist in identification of parts and under-
standing the functional operation of the D-150. amplifier.
A thorough reading of this manual and strict adherence to the in-
structions, procedures and cautions will assure many years of pro-
fessional quality service and listening enjoyment from your
CROWN D-156 Dual-Channel Power Amplifier.
1.2 EQUIPMENT DESCRIPTION
Tre 0-150 isa dual-channel medium power amplifier for ultra-low
distortion amplification from 5Hz to 20KHz with operation into
loads of 4-ohms:and higher. The-unit features extremely tow har:
monic and intermodulation distortion, very low noise, highest
“damping factor,” and quality parts and workmanship. The unit
may be wired to produce a balanced 50 volt monaural output. The
amplifier is fully protected against misrretched and shorted loads
by a resetting V-1 (volt-ampere) limiter having no obnoxious
muting or program delays. A thermal switch removes power from
the unit if overheating occurs due to insufficient ventilation.
The power supply features large computer-grade filter capacitors
giving over 20 joules of energy storage.
A total of 24 discrete transistors, 1 linear IC (dual op amp), 20
diodes and 1 bridge rectifier are utilized in a CROWN-ploneered
Class AB+B output circuit. The effective number of semi-
conductors is 40 transistors and 30 diodes.
The input voltage-ampiifiers, (IC), are powered by two voltage-
regulated supplies. This results in complete channel-to-channel
isolation and independence from line voltage variations.
Two level controls are mounted adjacent to the inputjacks to allow
balancing and optirnizing of systern levels.
ise BRaEmnEnEgaNIRitR ke nsonannannsnnnnnnnssnnonimnossnnnenans

Me
Power Output
Power Bandwidth
Frequency Response
LM. Distortion
Phase Response
Damping: Factor
Hur and: Noise
Verification
Load Impedance
Construction
input
Turon .
Circuit
Protection
Power Supply
Dimensions
‘Weight
Warranty
SECTION 2
SPECIFICATIONS
Power output not less than 75 watts R.M.S. per channel into 8 ohms (both channels operating), 20-
20,000Hz at rated distortion. Typically 100 watts R.M.S. per channel into8 ohms, 180 watts 8.M.S. per
charinel into 4 ohms.
Power bandwidth + 1dB, 5-20,000Hz at 75 watts R-M.S. per channel into 8 ohms.
+0.10B 20-20,000Hz at 1 watt into 8 ohms; + 1dB 4-100,000Hz.
1M. Jess than 0.05%, 0.01 watt to 76 watts, 60Hz and 7,000Hz mixed 4:1. Harmonic lass than 0.05%,
0.01 watt to 75 watts; 20-20,000Hz.
+£15°, 20-20,000Hz at 1 watt into 8 ohms. Gee graphs)
Greater than 200 orn 2676 te 1000Hz into 8 chimes.
11008 below.75-watts:R.M.S. output.
Each unit accompanied by its individual hand-entered proof-of-perfarmance report.
4 to 16-ohrns (complete stability with any load); dual binding-post outputs.
100% American-made-with industrial. grade construction-for years of continuous use.
Impedance —~ Norninal 25K ohm, screwdriver adjust on rear. Input sensitivity 1.2V for full output.
Standard °4” phone-jack on rear. : J
Instantaneous, with no program delay, and minimum thump.
Unique wideband, stable design utilizing one linear iC (dual op-amp). Total equivalent of 40 tran-
sistors, 24 diodes, and four rectifier-diodes.
Amplitieris short: and mismatch: and open-circuitproof. Unique V-1 limiting is instantaneous with no
thumps, cutout, ete.
Two massive capacitors with energy-storage exceeding 20 joules. Total of two regulated supplies for
complete isolation and stability. No fuses except AC powerline,
17" width, 544” high, 9° deep Grom mounting surface). All-aluminum construction with massive
chassis, and: extruded front-panel. Amplifier will pane!-mount in a 16%" x 5” opening (with optional
front panel). With adapters, staridard 19° rack tieurit,
22 pounds (24 pourids tack mount.
3-year on all parts, labor, and round-trip shipping.

3.1 GENERAL
- This: section contains: instalistion and operation instructions for
the D+150: arhplifier. Also included: are destriptiaris of the pro-
* tective mechanisms forthe amplifier and the liad: together witha
list of operating precautions to help clarify proper operating
procedures.
3.2 UNPACKING
imamediately upon: ‘peceipeot the ‘arn RE? shipenenc weber the
unitforany damage incurred intransit. The amplifier was carefully
inspected:-and-tested. and left the factory-unmarred. Notify the
———— comparty immediately ifany damage is found. Only
NOTE: The “basic” D-180 shown at right may be converted
for rack- or cabinet- (panel) mounting by installing the front
panel with brackéts or end-caps as shows below.
RACK MOUNTING
INSTALLATION
AND_OPERATION
the
consignee
may
initiate
a
claim
with
the
carrier
for
damage
dur-
ing
shipment.
However,
CROWN
will
cooperate
fully
ini
Sich
ah
event.
Be
sur
to
Save’
thé
carton-a6
evidence
at
eerie
far
he
:
shipper's inspaction.
CROWN
récommends
that
you
‘save
the
packing
|
materials,
even
it
the
unit
arrives
in
perfect
condition.
They
will
prove
valuable
in
preventing
damage
should
there
be
ovéas
1
Ship
the
unit.
Both
the
carton
end
internal
pack
are
specifically
de-
signed
for
protection
during
transit:
Do
not
ship
the
unit
without
this,
factory
pack”
Be
sure
to
returri
thewaerantyregistraticn
formtothe
CROWN
face
tory
within
ten
days
for
the
full
warranty
coverage.
ee i
CABINET MOUNTING
FIGURE 3-1.
0-150 MOUNTING DIMENSIONS

%
The D-150 may be custom oF rack-miounted if an accéssory front-
panel kit with rack-mounting brackets was purchased. The
installation of this kit is detailed in Figure 3-2. Refer to Figure
3-1 for mounting dimensions. Sufficient ventilation must be pro-
vided forthe unit. Airmust be allowed tocirculate overthe chassis,
atherwise. the amplifier.will-intenmitiently tur off due to the -
internal. thermal. protection. feature...Applications +-.other-than
standard “Hi-Fi” — requiring long, sustained signaisathigh power
levels may require the use of a cooling fan.
3.4. ACCESSORY PANEL pis INSTALLATION
MODEL PK)... 05
To install the D-150 amplitier ina : “custom configuration’ ue
cessory cabinet (Model 5-D or 5-R) or a rack, the accessory front
panelmust be-attached:first: Referto Figure: 3:2eso2.0006
1. Pull four rubber feet off the bottom of the amplifier,
2. Place amplifier on bench or table: stand on end with trans:
former. down,
“Amplifier” onthe front panel should foe tb
cpanel being-instalied: sae
4. Plastic wedges supplied with the panel kit should be forced inta
positions Land 2or Hoth ends of the unit as far as possible. Clip
or break off the excess part of the plastic wedges ~
5. Align-end-caps-to-the-unit-so-holes.“A”-and “B" match th
caps. Use 6/32 x % socket cap screws. (NOTE: Socket screws
may look as though they are cross threading but willstraighten
approximately half way through)
in. a “custom installation”, install a solid shelf to support.the
amplifier..The -shelf-top-surface should: be- flush with the bottom
edge of the required L6%," wide.x 5%" high-panel cutout.
When using angle brackets for rack mounting (Figure 3-2) always
have the brushed side of the anglé-bracket toward you. Simply
mount the end-brackets in-place of the end caps and rack mount:
as shown in Figure 3-1.
FIGURE 3-2.
PANEL
KIT
MOUNTING
-on
to
Figure
2.3,
In
applications
where
the
load
is
a
loudspeaker,
amplifier
protection
will
be
evidenced
by
distortion
inthespeaker.
fatchtheend. -
3.5
AMPLIFIER
PROTECTION
MECHANISMS
The
D-150
is
protected
against
all
the
common
hazards
which
Plague
highpower
amplifiers,
including
shorted,
open,
and
mis-
matched
loads;
overloaded
power
supplies;
excessive
temper-
ature;
chain
destruction
phenomena:
input
overiond
tetiee
and
high
frequency
overload
blowups.
é
Protection
against.
shorted
and
misrnatched-ioads
is:
‘provided:
by
an
instant-acting
Jimiter
which
instantaneously
linits
at
the
volt-
ampere
product
to
the
maximum
safe-stress.
value
eve
transistors...
“
The
area
in
which
the
amplifier
will
drive
the
load
without
being
V-i
limited
is
depicted
by
the
cross-hatched
areas
of
Figure
3-3.
if
a
load
initiates
protection
in
the
amplifi
it
can
‘be
detected
generally:
by.
watching:
the
wanster,
characteristics
ofthe
amplifier
Hy
The
audible
effect
ranges
from
something
resembling
cross-
overnatch
distortion
to
a
snapping
sound,
depending
on
the
overall
load
characteristics,
Speaker
systerns
which
are
truly
8
ohms.
or
greater
will
not
initiate
the
protection
system.
; FIGURE 3-3.
GRAPH
of
V-1
OPERATING
RANGE
of
D-180
OUTPUT
&,
y
ea

os,
The: AC. line for 120VAC is fused with a 4A, 250V.type AG fuse for
240, 250VAC, 2A type AG). The use of any other type of fuse will in-
validate the warranty.
A thermal Switch is mounted’ onthe Hones 10 protect the
amplifier against insufficient ventilation. If it becomes too hot, the
AC-line: power will be interrupted until the temperature fais to a
safe level, whereupon power will automatically be restored. When
such an event occurs, the’ external symptorns are: no output, anda
wartn anipiifier.
The ‘amplitier’s voltage-amplifier citcultry is designed t to.be. in-
hereritly current-intited. 1 any of the: aevices fail, no damage
occurs to the rest of the stages.
‘with the Vil limiter, protects the amplifier foi ‘blowers When hod
large RF input signals.
3.6" LOAD PROTECTION METHODS =
The most corrimon ofall protection schemes is a fuse in series with
the load. The fuse may be singte; fusin, erallsystem. Or, in
the case of a multiway speaker system, it ey ‘be rHUltiple with
Orie fuse wit éach speaker,
SPEAKER
FIGURE. 3-4.
FUSE SELECTOR NOMOGRAPH FOR
LOUDSPEAKER PROTECTION
Fuses
help
to
prevent
damage
due
to
prolonged
Overload
,
but
pro-
vide
esseritially
no
protection
against
damage
that
may"
bé
large
transients
and
Such:
To
mininiize
this
problem,
high:
instrument
fuses
“such
“as
Little
fise
361000
Series
are’
mast
appropriate
for
siich
applications.
For
a
niomopgraph
showing
fuse
Size
¥s,
loudspeaker
ratings
refer
to
Figure
34.
;
Another
form
of
load
protector
is
shown
schematically
in
Figura
3.
5.
Whenever
the
load
is
overdriven,
a
relay
switches
a
jamp
in
Series
with
the
load;
smoothly
relieving
the’overload.
The
lamp
then
doubles
as-an
overdrive
indicator
as
it
glows:
If
overdrive
ig
unreasonably
severe,
the
lamip
will
serve
ag
2
fuse.
By
adjusting
the
relay.tension
adjustment
and
the
protéction
level
control,
this
system
is
useful
from
25
to
200
watts
for
a
typical
8
ohm
ioad.
Another more sophisticated form of overload protector relieves
the overload by controlling the ampliier’s eu sigral which is
eT hise ; :
load: but also eliminates amplitie
possible 16 Operate the anipiifier at ids maximum level with: arain-
imum-of chipping. This device is shown schematically in Figure 3-
4, It features an overdrive indicator, distortionless photo-optical
control, and.a Protection Level control giving adjustment from 1W
to. 200W when driving 8 ohms. .
FIGURE 3-6.
PEAK POWER LIMITING COMPRESSOR
WITH OVERDRIVE INDICATOR

A common problem which causes damage.and irritation is the
turn-on thump problem typical to many signal sources. Figure 3-7
shows. the schematic of a muter which, when. inserted inthe input
signal line, mutes. for several seconds before connecting the
source to the amplifier, thereby eliminating turn-on transients. it
aiso removes turn-off transients occurring after the relay drops
See 00).
FOR LOAD PROTECTION
BO this imuter ig not required.
rany signal source
NOTE: When using the CAO
whose AC power is switched by the IC-160.
Followingare. ey number of operating precautions givenasanaidto
understandirig proper-and improper. amplifier usage:
1 Use care ‘ine taking connections, selecting signal sources,
and Gontvalling the i U
thay bé your own. CROWN is: ‘any damage done to
loads “due to careless ampliier usage or deliberate over:
powering. For pointers on load: ibe see paragraph 3.6:
2)-Néver parallel the two ou
OF — ‘them with an
without a series isglating capacitor. Such operations may
damage the device and/or needlessly activate the V-Himiting
(see Figure 3-3),
4. Do-not short.the.ground. lead.of:an output cable to the input
signal ground as oscil Fay result from forming such a
grourid loop... =
8. Operate and fuse the amplifier only as set forth in paragraphs
34.
6. Operate the amplifier from AC mains of not more than 10%
above the selected ‘fine voltage and only on’50, 60 or 400Hz
AG: Falling to comply with these: aes will sec siyatate ine
warranty.
7. Never connect the output toa power supply output, battery; or
power main. Damage incurred by such a hookup is not
covered by the warranty,
8. Do not expose the. amplifier to corrosive chemicals eehs as
soft drinks, lye, salt-water, ete. ~~
De To apt rt ecrmende fr ih ower industria
usage at frequencies above 20KHz.
10, Tampering.in. the. cireuit:-by unqualified. personnel or the
making of unauthorized circuit modifications invalidates the
warranty.
11. Donotexpose the output leads to areas likely to be struck by
lightning. Such an: installation, could invalidate the. amplifier.
3.8 CONNECTING OUTPUT LINES
input and output connéctors are located on the.chassis as shown
in Figure 3-8,
FIGURE 3-8.
REAR VIEW OF CHASSIS
Rt ig always wise to remove power from the unit and tum the input
level controls off while making connections, especially if the toad
is a loudspeaker system. This will eliminate any chance-of toud
blasts. CROWN is not liable for darnage incurred at any trarisducer
to its being overpowered! The use of the enclosed speaker fusesis
therefore highly recornmended:~ -
Before making connections, it is recommnended that the aperator
farniliarize himself wth the amplifiers protective system.
Reterence paragraph 3.6.
Because of the locations of the output connectors (color-coded
binding posts) it will be easiest to make these connections first.
High-quatity, dual “banana” plugs are the preferred connections
for permanent installations. ©

Because the output wire gauge and length raises the resultant
source impedance or lowers the Damping Factor by adding series: «
resistance,
the
nomograph
(Figure..3-11)
is
provided
for
wire
selection. For dynamic moving-coil loudspeakers the valueRy --
should preferably be. that. measured by an ohmmeter across the
voice coil, rather than the manufacturer's rating. For elec
speakers
and
such,
theynanufacturér’s
rated
impedance
should
Pa
be used for R, -
ff the load (matching. teanstoriner, inductance, or ibe
electrostatic speaker system) appears as a short-circuitatiow freé
quencies, a large non-pélarized: capacitor’ (paralleled with a
resistor)-should-be-placed:in
series.
withthe.
jgad.
For electrostatic speakers (if the manufacturer has not provided a
lar Capacitor oF S90- 708 mitdand 4
ohn power resistor should be placed in senes with the plus +)
speaker lead. This. will prevent lerge low-frequency currents from
darnaging ‘the: electrostatic” tansfortier ‘or from unnecessarily
activating the D-150's protectivé.system. An effective test to
determine if such parts are-needed is to measure the DC re-
sistance between the output-terminals with a
résistarice-is tess than 3 ohms, the parts si
shown schematically in-Figare- Ss 9.
40,200...
FIGURE 3:9.
SCHEMATIC FOR FULL RANGE
ELECTROSTATIC SPEAKER, CONNECTION
should nét be used. A cormmon exariple is the standard 3-
circuit “inch phone jack. and lug awen. wired - for stereo
sound. .
4. Connectors having low-current-carrying capacity are “vers.
5. Connectors having any tendency to short, or having shorted
leads, are unadvisabie. on
Most commercially-available- headphones employ a A-circuit 4%
inch phone plug which violates condition No. 2. This is no handi-
cap if # pad is inserted between'the atip: jack, which is only
sensibie when such a large amp! is coupied to such a small
HE this precaution is not only may the trans-
ducer te-Gairned out but permanent hearing loss could result. The
recommended pad is shown in Figure 3-10.
“FIGURE 3-10:
SCHEMATIC ‘OF EARPHONE PAD
3.9 CONNECTING INPUT LINES
Connecting the inputs will require observance of three basic pre-
cautions: Undesirable signals.to-the inputs, “ground foops;“and
feedback from output(s) to input(s). °
in high fidetity audio applications any good vacuun?-tube or solid-
State control center will operate’successfully into the 25K ohm
inputs “of the D-150. Occasionally a high-impedance output of
poorly-designed preamps will be encountered, and/or a larger
_ output coupling capacitor may be required (o prevent excessive
— fow-tr quency rolloff).
For. joudspeaker-driving applications, the vane should-be free of
large sub-audio or undesired low frequencies, as they cause over-
heating and overloading of the loudspeaker. To remove such low
frequencies, a series capacitor may be placed in the input signal
line. (The graph of Figure 3-12 indicates the effectofthe size of the .
capacitor on the frequency response. 1) Only a low-leakage paper,
oF cause general overload
‘sewing -tate stage of the amip (which is employed to provide RF
overload protection). The following filters are recommended for
such applications (Figure 3-13),
A second precaution is “ground loops” — electronic jargon for un-
desirable circulating currents flowing in a grounding system. A
commion form of loop (possibly resulting in hurn In heoutpuld is a
pair of input cables whose area is subjected to a magnetic hum

a8 ae
= 2. :
RESISTANCE DAMPING
(ohonst
FACTOR
: 100
te
Ie cai aes
aay Fale illil
ame
3 FIGURE 3-12.
' (GRAPH FOR SELECTION OF INPUT CAPACITOR
Ot
oe Ry
SOURCE inno00 8) + ANNEALED
gee ‘
RESISTANCE OOF COPPER
fohens} 2-cONnD. 300 WIRE
. CABLE TO wer
gas FIGURE 3-11.
SOURCE: AESISTANCE end DAMPING FACTOR VS. LENGTH. and ‘SIZE of OUTPUT LEADS
field. in practice both cables: should, fie: together along their
minh SUEE ginal Fay Ls MAR EGO
A third precaution (with i input and output grounds together, agin
flowing in the loop. in industrial use, “even the AC power line may
provide this feedback path. Proper grounding, ‘and isilation of ih-
puis, of-.comimon-AC- line. devices.is poe practice: Refer: “to,
PASE famine pastons, ne
3. 10 CONNECTING POWER
readily av ahs commercially for
adapting this to a two-wire system if necessary. iat
The ‘ariplifiér offers two standard fine-voltage connections 120
and 240 VAC. The tag attached to the line cord indicates for which

Because the output wire gauge and length raises the resultant
source impedance or towers the Damping Factor by adding series.
resistance, the nomograph (Figure..3-11) is provided for wire
selection:
For
dynamic
moving-coil
loudspeakers
the
value
Ry:
«
should preferably be. that. measured by an ohmmeter across the
voice coil, rather than the manufacturer's rating. For elect
speakers and such, thenarufactuter' s rated impedance should.
be used for Ry.
if the load (matching, transformer, inductance, or fulbrange
electrostatic speaker system) appears as a short-circuit atlow ire
quencies, a large non-polarized capacitor (paraticled with a
resistor) should be placed:in series with the load.
For electrostatic speakers (if the fnanufacturer has not provided a
capacitor) an external. non: capacitor of 890-708 mid and 4
ohm power resistor should ‘be placed in series with the plus (+)
speaker: lead: “This: will prevent = low-frequency currents from
activating the D-150's protective system. Ari effective test to
determine if such parts are needed is to measure the OC re-
a meter. {f the
resistance is less than 3 ohms, the parts ‘should be added as
shown
schernatically
in
Figure
39,
Z
FIGURE 3-9.
SCHEMATIC FOR FULL RANGE
ELECTROSTATIC. SPEAKER.CONNECTION
“to ba tied coe durine tiated ) 4
should not be used. A commen example is the standard 3-
circuit “inch phone jack. and. Plug: when, wired, Aor stereo.
4. Connectors having low-current-carrying capacity are “ver-
boten.’ .
5. Connectors having any tendency to short, or having shorted
leads, are unadvisable. Es
Most comunercially-availabie headohonee employ a 4-circuit K-
inch phone plug which violates condition No. 2. This is no handi-
cap if d pad is inserted between! @ alvip-and jack, which is only
sensible when such a large amp fer i J
transducer. Hf this precaution is igri ; NOt Only may the trans-
ducerbebdrned out but permanent hearingloss could result. The
recommended pad is shown in Figure 3-10.
"FIGURE 3-10.
SCHEMATIC OF EARPHONE PAD
3.9 CONNECTING INPUT LINES
Connecting the inputs will require observance of three basic pre-
cautions: Undesirable signals to the inputs, “ground loops, ” and
feedback from output(s} to input(s).
In high fidetity audio applications any good vacuum-tube or salid-
state control center will operate successfully into the 25K ohm
inputs-of the B-150. Occasionally a high-impedance output of
poorly-désigned preamps will be encountered, and/or a larger
output coupling Capacitor may be required (to prevent excessive
low. frequency rolloff)..
For cles esosving sulications, the input should be free of
large sub-audio or undesired low frequencies, as they cause over-
heating and-overloading of the loudspeaker. To rermave such low
frequencies, a series capacitor may be placed in the input signal
line.
(The
graph
of
Figure
3-12
indicates
the
effectofthe
sizeof
the
capacitor on the frequency response.) Only a jow-leakage paper,
is employed to provide RF
overload protection). The following filters. are recommended for
such applications (Figure 3-13).
Asecond precaution is “ground loops” — electronic jargon for un-
desirable circulating currents flowing in a grounding system. A
common form of loop (possibly resulting in hum in the output) is a
pair of input cables whose area is subjected to.a magnetic hum
q
i
4
a
:
i
ET
|
j
H
|
:
:
3

i Ly eb Ry
1OAD
Rs
SOURCE
tayio0o
fi)
+
ANNEALED
ald
a
a
:
RESISTANCE
|
DAMPING
-
RESISTANCE
000%
COPPER
fehon}
FACTOR
{ohms}
2comp.
300
WIRE
—-
cABiE
tavee)
2:
feat}
eT)
99,
‘
5
10
2
2
6
20:
1s
é
if
20
ee
:
yet
bees
ge
o
5 2
< FIQURE3-1 1.
SOURCE RESISTANCE and DAMPING FACTOR VS. LENGTH and SRE of OUTPUT LEADS
_ figid. In practice, both cables should. lie together along their,
and away trom the power transformer. Tying the input and
output grou ene al te aground loop.
3:10 connecting POWER
The arnplifier is furnished with a three-wire AC plug as standard
equipment. Adaptors are readily available commercially for
adapting this to a two-wire systern if necessary.
ae
"FIGURE
3-12.
The
amplifier
offers
two
standard
fine-voltage
Connections:
120
GRAPH
FOR
SELECTION
OF
INPUT
CAPACITOR
and
240
VAC.
The
tag
attached
to
the
line
cord
indicates
for
which
Poe

Sees” TT
MOTE: A tod teen de ane 10KM aaKey, souks
increcsad to 5002 by sy
auoripriate resistor,
FREQuenct
5 FIGURE 3-12.
LOW-PASS FILTERS FOR SEVERE RF AT INPUTS -
voltage the Sg Gnitg are connected for
120 VAC. Figure 3-14 shows plétarially how the 240.VAC con-
hected ufit Should appear. Note the change to a 2Acline fuse. ©
Whelt testing’ the ‘amplifier, the line voltage miust be the peak-
equivaient to.a sinusoid of the indicated line voltage when at full
lead. Line regulation problems can introduce serious errors inthe ~
eases onan amplifier of this. size.
should attempt stration of the fine
voltage connections.
RED BLK wire
|. connect BLK-W wire
fram 1 and BLK wits
from 4 to 3
on WHY wire
"WOVE: ting fuse fe now ZA
~ FHGURE 3-14.
LINE
VOLTAGE
CONNECTIONS
(240
VAC}
3.11, OPERATING 5 CONTROLS
The -0- 150 ¢ contains all the facilities essential for a high per-
formance amplifier.
~- The-input-controls-are-mounted-by-the input jacks. Each control
should be adjusted for the desired amplifier gain or output ievel.
When the control.is fully. CW, the. gain.is 2608. as Seternined ey
precision 1% resisiors in the D-150’s feedback loop.
FIGURE 3-16.
OPERATING CONTROLS
14
Hae ER asta
/
i

FIGURE 3-16.
TYPICAL HI-FI INSTALLATION
12
on
URNA EEEtRRAanees

3.12 NORMAL HI-Fi INSTALLATION
1. Two-conductor speaker cables must connect to the OUTPUT
dual binding posts using terminal lugs, tinned ends, or the
special “banana” plugs supplied with the D-150. Connect the
in-line fuses as recommended in the Accessory Bag and Figure
3-16.
: Since the D-150 is a“basic amplifier,“ the main outputs of the
control-center or “preamplifier” must be connected via
shielded eudio-cables to the two jacks marked INPUT. Use
RCA-pin. at preamp. and standard./-in. phone-plug at the D-
150.
The two cables should be tied parallel along their entire length
using the accessory cable ties.
. U/L requirements prefer a 3-wire AC power connector; how-
aver, proper Corrections to a switched’ outlet on the contrat
center requires the use of a 3-to-2 wire adapter. NOW, plug the
AG:into a switched outlet on the contro! center. *
13
4. Your Control Center may now be turned on. Then advance the
D-150 Input-Gain Controls about 4-open (150° clockwise).
When using the CROWN IC-150 Control-Center, the LOUDNESS
should attain almost full rotation (2 to 4 o'clock) for loudest
“concert-hall” volume. If at 3.o'clock the volume is low, increase
the 0-150 input gain controls; if too high, decrease the 0-150
gains.
3.13 CLEANING
The CROWN D-150 has a rugged anodized front panet (optional)
for life-time service. The panel can be cleaned with a moist cloth
and mild detergent. Never use steel wool, scouring powder, lye
solution, or arly strong abrasive cleaner as these will damage the
panel’s-tinish.
The chassis should require no more cleaning than periodic dust-
ing with a clean dry cloth.

4.1 PRINCIPLES OF OPERATION
The D-150 has twodirect-coupled amplifier circuits which employ
a.dual.IC op.amp.and silicon transistors in all anplifier stages, The.
CROWN-designed and developed circuit represents a level of
quality and performance presently unequated in the field of audio
amplifier design.
Thé. dual 1C op ainp is of a low noise type having a large gain band-
width, The results of using Heres nut eeae real wis tats
record low values. The typical full output (75w, ‘Bonms) SMPTEIM
is. 0.002%.. This. implies. that the. full power.1KHz. THD is inthe
vicinity of 0.0005% which is below the capability of present har-
monic distortion measurement systems. Multiple feedback loops
ara employed to allow a Maximum of overall feedback.
The lack of noise is evidenced by a typical 20Hz-20KHz effective
input noise of 1-25 0 volts which produces an effective B ohmicut-
ut.of. B0.micro-micro.(pica), waits.
The. output stage is a quasi-complimentary format employing the
CROWN. class AB+B technique which uses no bias current in the
output transistors. The result is maximum efficiency with min-
imum crossover notch distortion and idling amplifier-heat. Thus
16
SECTION 4
CIRCUIT DESCRIPTION
there is no bias current adjustment, as the output circuit is not
temperature-tolerance critical.
inthe new. output circuit, the driver transistors carry the bias.cur-.
tent, while the output transistors serve only as boosters. The out:
put transistors sense wher the driver transistors are delivering sig-
nificarit currentto the load anc take over and deliver the large load
currents.
The output circuit is protected by a V-I limiter which limits the
drive to the output configuration whenever the output transistors
are overloaded, V-! (volt-ampere) limiting Is inherently superior to
all other forms of protection as it directly senses the overload con-
dition and acts instantly to relieve the overload, actingonty so long
as the overload exists, The result is Coripiéte freedom from pro-
‘Star delays with réliability arid iraximun safe output power.
The power supply is a continuous-duty type. The main OC sup-
plies are full-wave capacitor input type with a heavy duty bridge
rectifier assembly. Computer grade electrolytics furnish over 20
joules. of energy. storage.
The D-150 represents nothing short of the highest quality in both
circuitry and components: it should provide a lifetime of trouble-
free service for the most discriminating users. ,

ort,
ponent replacement procedures.” Use ‘this: information in-con-
junction with Section:6, Schematics, Parts Lists. and Component.
tocation, to obtain best results.
5.2 SERVICE POLICIES:
Bus to the sophisticated yeuley ont a fully erty pomneatent
service technician should be allowed to service the D-150 ampli-
fies. User servicing Should be: confined te tautine replacement of
the fuse on the rear panel. Please observe the following label on
the rear panel.
‘mee ee CROWN 0-160 ari to fh tact fore
vice, authorization should be obtained fromthe service manager.
Alt rit pel mcr iether aa
Fhig ‘warranty:does not-extend to. fuses, and/or-component or
acu a Pirated aoc etme damage
“Apr application tor a FREE 3-year WARRANTY TITLE WS indluded
with the instruction manual received with the equipment. Upon
Feceipt
o'
of
this
completed
tom,
CROWN.
AL
applias
tothe
original
end
-purchaser
and
will
be
issued
only
upon
receipt
of
the
application,
impertant!! 1 Note the following caution which is screened en the
amplifier rear panel. CAUTION! NEVER. DIRECTLY. CONNECT
The 0-150 amplifier is specifically. designed for-easy. servicing. It
may be partially disassembled and stil! -be made -operatiorial for
bench testing and servicing. This may be accomplished by re-
moving the bottom cover, transformer cover and wrap-around,
and the board and slectronics: ‘cover (para 15:
These stans provide sasyaccess to nearly all n -comiponents of
the amplifier. Those that are not now accessible for servicing can
be removed following the a eee ee
dividual: assemblies.
Refer-to Figure 6-2,
1. Remove pee ae arnplifier.
moe ree pene ‘has been installed on the ampli-
“frorfithe top of the! ransforner cover
GD) , and remaye the transformer coverand the transformer
» Wep-around | owes
4, Rernove two screws —e ee ee
tronics cover 45).and remove the cover,
5. Reverse the above sequence of actions. ip reassemble the
amplifier.
i ERIM UT RUE aawlannasnansnasen:

Removal of Contre Plate Assembly
Reter to Figure 6-400 0) :
1.
Remove
board
and
electronics
cover
as
described
in
para-
graph
5.4.1,
Step
4.
2.
Remove
two
screws
(©)
from
top
of
contro}
plate
assembly,
40951.
3.
Carefutly
lift
contro!
plate
assembly
and
turn
nearest
edge
(where.
screws
were
removed)
upward
until
bottom
of
contro!
plate
is
accessible.
Do
not
place
unnecessary
strain
on
wiring
connected
to
main
PC
board.
Refer to Figures 6-2 and 6-3.
1.
Remove
board
and
electronics
cover
(paragraph
5.
At,
Step).
Both
component
and
solder
sides
of
board
are
nowaccessible.
3. The IC is a plug-in component. -
4.
Resistors
(R111,
R211)
(selected
bias
resistors)
aré
plug-in
§.4.4 Selaorat of nt ay
Potentiometers (R101, R
to-terminals of new input level
6.
Pacers
new
aN
in
‘poshien
and
‘replace
contra!
nut
7. Replace control plate assembiy; paragraph 542.
‘8:
Replace
board
arid
electronics
cover,
paragraph
6.4.1.
5.4.5 Replacement of Thermal Switch, SW-1
Refer to Figure 6-2.
. Remove bottom cover (paragraph 5.4.1, Step 2).
2. Remove beard and electronics cover (paragraph 5.4.1, Step 4).
Disconnect two Faston connectors @ @ from terminais of
thermal switch SW-1.
4. Remove two each, screws
Ge) , solder tugs so
the chassis.
5. Place new thermal switch SW-1 in-position and-replace hard.
ware removed in Step4,
_
ad
shex nuts G3 , star washers
thermal switch SW-1 from
Refer to Figure 62. 7
1. Remove: trarisformer cover -and transformer wraps: -around
(paragraph 5 4:7 “Step 3). :
ecrrcaeh tae Stet a
S
a
2
ee
@ cor vane dm nt
ince tint igs DEA position and replace hardware ré-
moved in'Step 4.
6. Recorinect four Faston ¢ connectors (19) _) @ to terminals of
bridge OM I.
Ve Replace bottom COVEr w(patigrochvbd: 1, Step 2).
4. Remove,
bad
8. Replace. “transformer ‘cover and ‘transformer wrap-around
(paragraph 5.4.1, Step 3).
Refer to Figure 6-2.
1: Tessie bation cove <paraieph 6.4.2, Step 2).
2. Remove. transformer. cover. and ‘transformer wrap-around
(paragraph 5.4.1, Step 3).
3. Remove ene Faston-cannector @. Bt fromm filer capacitor
(C23 er C24) terminal.
J RRR

Ne
twopanel washers
4. Remove twoscrews (7), one solder tug!
from. ie filter @) (8) and. two fiber shoulder. washers.
capacitor terminals.
5. Remove defective iter capacitor (C23, or 24) from the
chassis.
6. ae eter capac poston and replace harder
.. removed in. Step 4. .
7, Réconnect Faiton connector ® @ to fier capacitor
terminals.
8. Replace transformer cover and transformer wrap-around
“(paragraph 5.4.1, Step 3).
9. Replace bottom cover (paragraph § 4.1, step).
5.4.8 Replacement of Output Inductors,
Replace and-L202
Referté Figure 65.
om
cover
(paragraph
6.4.1,
Step
2),
2.
Remove
board
and
electronics
cover
(naragraph
54.1,
Step
4).
_ 3. Unsoler one end of brown collwire (2) from the output bind-
‘ing post terminal eS a driver
transistor terminal. . 2
hex nut 7), star washer (6) vaper®
output coil toroid core and brown wire C1)
5. Place ‘ew ‘output Coll toroid core and new brown wire in
position and. replace hardware removed-in Step 4:
6: Soldier ong ene sf brown coil witeQ to the output Binding post
terminal
and
the
other
,
Snd-to
the
adjacent
driver
transistor
tarininal:
7. Replace boarcl and electronics cover (paragraph. 4. 1, Step 4).
_.8.. Replace bottom cover (paragraph 5.4.1, Step 2).
Refer to Figure 6-2.
ds Remove bottom:-cover (paragraph: 5.4.1, Step.
4 frie ies) Gtr noe as een a
: .Mlove hardware shown and the defective tra
transisior Case and the chassis wih a” Thedt-condcting
compound (06-340).
9
6. Install new transistor and tighten a ai
assure good heatsinking.
7. Resolder wires and corriponent feeds te femoved from transistor
terminals in Step 3 above.
8. Replace board and electronics c cover er (paragraph 54.1, step4).
9. Replace bottom cover: (paragraph 5.4.1, Stap.2).
5.4.10 Replacement of Power Transformer, T-1
1. Remove bottam cover (paragraph 5.4ck, Step 2) or
Be Penis Neate ee “Over an Seanetorneer wrap-around
‘(Paragraph 5.4.1, Step. 3).
3. Desi cei trailor nae wat pas through the
ee calalne iia salloh coenentoes edie DML:ter.
“ninalsandremove Faston connectors: > @ fromthe
red wires.
b. One yellow wire; unsoiderfrom solder. tug(@)atiunction ‘of
capacitors.C23.and.C24..
¢ One black and one white wire; unsolderfromterminal strip
d.. One black/red wire agd one black/white wire:iunsolder
__: from terminal strip i
4, Pull alt wires back through hole'in chassis:
§. Remove hardware: securing transformer-T1.to the chassis.
2 — =
7 Cut feads.on ou Unestsenar Ti tosame ene as those on
the transformer being replaced. r
8. Place new banstonmer TE pil iad ha hes
10. Connéet | seven transformer wires to destinations shown in
Step 3,
7 é transformer cover’ arid tansformer Wrap-around
(paragraph 6. 4, 1, Step 3).
12. Replace bottom cover (paragraph $41; Step 2)