Yorkville ap4040 schematic

WORLD HEADQUARTERS

1200W into 4 ohms per channel

CANADA

Yorkville Sound

550 Granite Court Pickering, Ontario

L1W-3Y8 CANADA

WEB: www.yorkville.com

Yorkville Sound Inc.

4625 Witmer Industrial Estate

Niagara Falls, New York

U.S.A.

14305 USA

AP4040

1. Parts List

2. Pot Board

• M1128 Schematic 1v1

• M1128 PCB layout 3v0

3. Input Board

• M1129 Schematic 2v1

• M1129 PCB layout 4v0

4. Power Supply Board

• M1147 Schematic 1v4

• M1147 PCB layout 4v0

5. Power Amp Module

• M1146 Schematic1v3

• M1146 PCB layout 5v5

4. Service Kit

• M1146

Voice: (905) 837-8481

Fax: (905) 837-8746

Quality and Innovation Since 1963

Voice: (716) 297-2920

Fax: (716) 297-3689

SERVICE MANUAL

Manual-Servive-ap4040-2v9.pdf v.2.9 6/2002

Printed in Canada

IMPORTANT SAFETY INSTRUCTIONS

INSTRUCTIONS PERTAINING TO A RISK

OF FIRE, ELECTRIC SHOCK,

OR INJURY TO PERSONS.

CAUTION:

TO REDUCE THE RISK OF ELECTRIC SHOCK, DO

NOT REMOVE COVER (OR BACK).

NO USER SERVICEABLE PARTS INSIDE.

REFER SERVICING TO QUALIFI ED

SERVICE PERSONNEL.

Read Instructions:

The

Owner's Manual

before operation of your unit. Please, save these instructions for future reference.

Packaging:

Keep the box and packaging materials, in case the unit needs to be returned for service.

Warning:

When using electric products, basic precautions should always be followed, including the following:

Power Sources:

Your unit should be connected to a power source only of the voltage specified in the owners manual or as marked on the unit. This unit has a polarized plug. Do not use with an extension cord or receptacle unless the plug can be fully inserted. Precautions should be taken so that the grounding scheme on the unit is not defeated.

Hazards:

Do not place this product on an unstable cart, stand, tripod, bracket or table. The product may fall, causing serious personal injury and serious damage to the product. Use only with cart, stand, tripod, bracket, or table recommended by the manufacturer or sold with the product. Follow the manufacturer's instructions when installing the product and use mounting accessories recommended by the manufacturer.

The apparatus should not be exposed to dripping or splashing water; no objects filled with liquids should be placed on the apparatus.

Terminals marked with the “lightning bolt” are hazardous live; the external wiring connected to these terminals require installation by an instructed person or the use of ready made leads or cords.

No naked flame sources, such as lighted candles, should be placed on the apparatus.

Power Cord:

The AC supply cord should be routed so that it is unlikely that it will be damaged. If the AC supply cord is damaged

OPERATE THE UNIT

Service:

The unit should be serviced only by qualified service personnel.

should be read and understood

DO NOT

SAFE_V4.doc Version 4.0 02/11/99 11:54 AM

INSTRUCTIONS RELATIVES AU RISQUE

DE FEU, CHOC ÉLECTRIQUE, OU

BLESSURES AUX PERSONNES.

AVIS:

AFIN DE REDUIRE LES RISQUE DE CHOC ELECTRIQUE,

N'ENLEVEZ PAS LE COUVERT (OU LE PANNEAU

ARRIERE). NE CONTIENT AUCUNE PIECE REPARABLE

CONSULTEZ UN TECHNICIEN QUALIFIE

Veuillez lire le manuel:

Il contient des informations qui devraient êtres comprises avant l'opération de votre appareil. Conservez S.V.P. ces instructions pour consultations ultérieures

Emballage:

Conservez la boite au cas ou l'appareil devait être retourner pour réparation.

Warning:

Attention: Lors de l'utilisation de produits électrique, assurez-vous d'adhérer à des précautions de bases incluant celle qui suivent:

Alimentation:

L'appareil ne doit être branché qu'à une source d'alimentation correspondant au voltage spécifié dans le manuel ou tel qu'indiqué sur l'appareil. Cet appareil est équipé d'une prise d'alimentation polarisée. Ne pas utiliser cet appareil avec un cordon de raccordement à moins qu'il soit possible d'insérer complètement les trois lames. Des précautions doivent êtres prises afin d'eviter que le système de mise à la terre de l'appareil ne soit désengagé.

Hazard:

Ne pas placer cet appareil sur un chariot, un support, un trépied ou une table instables. L'appareil pourrait tomber et blesser quelqu'un ou subir des dommages importants. Utiliser seulement un chariot, un support, un trépied ou une table recommandés par le fabricant ou vendus avec le produit. Suivre les instructions du fabricant pour installer l'appareil et utiliser les accessoires recommandés par le fabricant.

Il convient de ne pas placer sur l'appareil de sources de flammes

nues, telles que des bougies allumées.

L'appeil ne doit pas être exposé à des égouttements d'eau ou des éclaboussures et qu'aucun objet rempli de liquide tel que des vases ne doit être placé sur l'appareil.

Les dispositifs marqués d'une symbole “d'éclair” sont des parties dangereuses au toucher et que les câblages extérieurs connectés à ces dispositifs de connection extérieure doivent être effectivés par un opérateur formé ou en utilisant des cordons déjà préparés.

Cordon d'alimentation:

Évitez d'endommager le cordon d'alimentation.

L'APPAREIL

Service:

Consultez un technicien qualifié pour l'entretien de votre appareil.

PAR L'UTILISATEUR.

POUR L'ENTRETIENT.

N'UTILISEZ PAS

si le cordon d'alimentation est endommagé.

AP4040 Parts List 3/8/99

YS # Description Qty. YS # Description Qty. YS # Description Qty.

3570 14 PIN SCKT 641261/3 OR W3114T 1 4520 10K TRIM POT (ENCLOSED) 2 4990 1/4W 8K2 5%MINI T&R RES 2 5906 RED 3MM LED 1V9 20MA .4 SPACER T&R 3 4390 _10K AUDIO DETENT STYLE"P22"16MM 2 4762 1/4W 9K760 0.1% *** T&R RES 8 5908 GRN 3MM LED 1V9 20MA .4 SPACER T&R 3 2448 15.0 AMP CIRCUIT BREAKER 1 4800 1/4W 10K0 1% T&R RES 3 6405 RED 3MM LED 1V7 5MA BRIGHT PACE 3 3410 RED ON LEFT DUAL BINDING POST TPP4 1 4829 1/4W 10K 5% T&R RES 4 6408 GREEN 3MM LED 1V9 5MA FROSTED 3 3415 RED ON RIGHT DUAL BINDING POST TPP4 1 4940 1/4W 10K 5% .2"U T&R RES 1 6419 BRIDGE 35A 400V WIRE LEAD GI3504 2 3918 1/4" SLIM JACK PC MOUNT W/SCREW 2 4983 1/4W 10K 5%MINI T&R RES 8 6425 BAV21 200V 0A25 DIODE T&R 4 3628 PC-MOUNT 250TAB SPEAKON #4SCREW GRY 3 6116 1/4W 10K0 1%MINI MF T&R RES 12 6438 1N4004 400V 1A0 DIODE T&R 17 3657 FEMALE XLR PC MOUNT HORIZONTAL 2 4856 1/4W 12K 5% T&R RES 4 6825 1N4148 75V 0A45 DIODE T&R 48 3860 FAN 80MM X 80MM 40CFM 12VDC 1 4630 1/2W 15K 5% T&R RES 2 6934 MR854 400V 3A0 DIODE FAST RECOV 20 3821 HEYCO #1200 STRAIN RELIEF 1 4830 1/4W 15K 5% T&R RES 4 6439 1N5225B 3V0 0W5 ZENER 5% T&R 2 8701 4-40 KEPS NUT ZINC 20 4771 1/4W 17K8 1% T&R RES 2 6440 1N750ARL 4V7 0W5 ZENER 5% T&R 9 8793 4-40 HEX NUT ZINC 3 6125 1/4W 18K 5%MINI T&R RES 2 6461 1N5240BRL 10V0 0W5 ZENER 5% T&R 1 8760 6-32 KEPS NUT TIN PLATED 64 4885 1/4W 20K 5% T&R RES 4 6450 1N5242B 12V0 0W5 ZENER 5% T&R 4 8800 6-32 KEPS NUT ZINC 3 6123 1/4W 20K0 1%MINI MF T&R RES 6 6822 1N4745A 16V0 1W0 ZENER 5% T&R 4 8720 #8 SPRING NUT 2 4777 1/4W 21K5 1% T&R RES 2 6824 1N5246B 16V0 0W5 ZENER 5% T&R 2 8797 5/16-18 KEPS NUT JS500 1 4632 1/2W 22K 5% T&R RES 8 6432 1N5248B 18V0 0W5 ZENER 5% T&R 2 3797 TO-247 THERMO CONDUCTIVE PAD 4 4832 1/4W 22K 5% T&R RES 2 6429 1N4747A 20V0 1W0 ZENER 5% T&R 1 3815 TO3 PREGREASED MICA 56-03-2AP 32 6118 1/4W 22K 5%MINI T&R RES 1 6465 1N5250B 20V0 0W5 ZENER 5% T&R 1 3846 TO220 THERMO PAD LARGE HOLE 56359B 8 4833 1/4W 27K 5% T&R RES 8 6463 1N5251BRL 22V0 0W5 ZENER 5% T&R 1 3580 12 CIR WAFER W/LCK VT 0.1" 1 4840 1/4W 33K 5% T&R RES 3 6433 1N5257B 33V0 0W5 ZENER 5% T&R 4 3583 8 CIR WAFER W/LCK 0.1" 2 6122 1/4W 33K 5%MINI T&R RES 1 5101 BC550C TO92 NPN TRANS. T&R 14 4597 22AWG STRAN TC WIR 25 4834 1/4W 47K 5% T&R RES 1 5102 BC560C TO92 PNP TRANS. T&R 14 4599 22AWG SOLID SC WIR T&R 114 6119 1/4W 47K 5%MINI T&R RES 4 5103 MPSA06 TO92 NPN TRANS. T&R 3 5299 24AWG SOLID SC WIR RAD 40 4835 1/4W 56K 5% T&R RES 8 5108 2N5401 TO92 PNP TRANS. T&R 2 4745 5.0W 0R1 5% BLK RES 12 4898 1/4W 91K 5% T&R RES 4 5113 MPSA42 TO92 NPN TRANS T&R 2 4749 5.0W 0R15 5% BLK RES 4 4838 1/4W 100K 5% T&R RES 2 5114 MPSA92 TO92 PNP TRANS T&R 2 4974 1.0W 0R47 5%FLAME PROOF T&R RES 2 6120 1/4W 100K 5%MINI T&R RES 2 6854 2N6517 TO92 NPN TRANS. 3 4677 1/2W 1R 5% T&R RES 4 4851 1/4W 120K 5% T&R RES 2 5105 MPSA13 TO92 NPN DARLINGTONT&R 2 4973 1.0W 1R 5%FLAME PROOF T&R RES 4 4886 1/4W 200K 5% T&R RES 1 5106 MPSA63 TO92 PNP DARLINGTONT&R 1 4688 1/2W 2R2 5% T&R RES 3 4641 1/2W 220K 5% T&R RES 2 6814 MJF6668 221D- PNP DARLINGTON 1 4911 1/4W 2R2 5% T&R RES 8 4668 2.0W 220K 5%10MM BODY T&R RES 2 6815 MJF6388 221D- NPN DARLINGTON 2 4748 2.0W 3R9 5% BLK RES 2 4841 1/4W 220K 5% T&R RES 2 6873 MJE340 TO126 NPN TRANS 6 4733 5.0W 5R6 5% BLK RES 2 6126 1/4W 220K 5%MINI T&R RES 6 6874 MJE350 TO126 PNP TRANS. 6 4594 1/8W 10R0 2%FLAME PROOF T&R RES 2 4843 1/4W 470K 5% T&R RES 2 6752 MTP10N15L TO220 N CHAN MOSFET 2 4605 1/8W 10R 5% T&R RES 1 4844 1/4W 1M 5% T&R RES 1 6925 MTP8P20 T220 P CHAN MOSFETT 2 4610 1/4W 10R 2%FLAME PROOF T&R RES 10 4948 1/4W 1M 5% .2"U T&R RES 1 6900 YS6900 (22) TO3 NPN TRANS. 16 4930 1/4W 10R 5% .2"U T&R RES 1 4951 1/4W 4M7 5% .2"U T&R RES 2 6989 MJL1302A T03P PNP TRANS PWR 2 4591 1/8W 22R1 1%FLAME PROOF T&R RES 2 6132 1/4W 8M2 5%MINI T&R RES 2 6990 MJL3281A T03P NPN TRANS PWR 2 4589 1/8W 33R 2%FLAME PROOF T&R RES 4 3699 RELAY 2C 01AMP DC48 ???MA PC-S 1 6927 YS6927 (23) TO3 PNP TRANS. 16 4607 1/8W 39R 2%FLAME PROOF T&R RES 10 3735 RELAY 1A 16AMP DC48 011MA PC-C 1 6840 MC33078P IC DUAL OP AMP 5 4899 1/4W 39R 5% T&R RES 6 3604 21" 14C-28AWG DIP HDR CABLE .050" 1 5190 MBS4992 TO92 8V5 DIAC T&R 2 6134 1/4W 47R 5%MINI T&R RES 2 3706 13" 8C-26AWG RIB 1 W/LCK HDR 0.1" 2 6444 MAC224-4 TO220 40A TRIAC 200V 2 6200 1/4W 47R5 1%FLAME PROOF T&R RES 2 3740 15" 12C-26AWG RIB 1 W/LCK HDR 0.1" 1 6859 NSL-28AA OPTO-COUPLER 2 4811 1/4W 68R 5% T&R RES 2 8865 4-40 X 5/16 PAN PH MS SJ500 2 6880 4N35 OPTO-COUPLER 4 4593 1/8W 150R 2%FLAME PROOF T&R RES 4 8742 4-40 X 3/8 PAN PH TAPTITE JS500 2 6478 AS35FN-TO92 TEMPERATURE SENSOR 2 4859 1/4W 150R 5% T&R RES 2 8861 4-40 X 3/8 PAN PH MS SJ500 8 6489 5R0 20% NTC THERMISTOR 2 4984 1/4W 150R 5%MINI T&R RES 2 8741 4-40 X 1/2 PAN PH MS JS500 11 5401 _10P 500V 5%CAP T&R RAD CER.2"NPO 4 4909 1/4W 200R 5% T&R RES 6 8827 4-40 X 1/2 FLAT PH TAPTITE SJ500 6 5410 100P 100V 10%CAP T&R BEAD NPO 2 6201 1/4W 200R 1%FLAME PROOF T&R RES 6 8871 4-40 X 5/8 PAN PH MS SJ500 8 5197 220P 100V 2%CAP T&R RAD CER.2"NPO 1 4645 1/8W 220R0 1%FLAME PROOF T&R RES 4 8799 #6 X 1/4 PAN PH TYPE B JS500 2 5412 220P 100V 10%CAP T&R BEAD NPO 13 4857 1/4W 220R 5% T&R RES 6 8832 6-32 X 1/4 PAN PH TAPTITE SJ500 1 5417 330P 50V 10%CAP T&R BEAD NPO 2 4977 1/4W 220R 5%MINI T&R RES 5 8801 6-32 X 3/8 PAN PH TAPTITE SJ500 4 5201 470P 100V 5%CAP T&R RAD CER.2"NPO 2 4606 1/8W 249R 2%FLAME PROOF T&R RES 8 8829 6-32 X 3/8 FLAT PH TAPTITE BO#4 HEA 18 5416 470P 50V 10%CAP T&R BEAD NPO 2 4867 1/4W 270R 5% T&R RES 2 8761 6-32 X 1/2 PAN PHIL MS ZINC CLEAR 64 5273 __1N5 200V 5%CAP T&R RAD CER.2"NPO 2 4986 1/4W 270R 5%MINI T&R RES 2 8806 6-32 X 1/2 PAN PH TAPTITE SJ500 2 5427 __2N2 500V 10%CAP T&R RAD CER.2" YB 6 4855 1/4W 330R 5% T&R RES 2 8837 6-32 X 1/2 ROUND PH MS SJ500 1 5209 __4N7 250V 5%CAP T&R RADIAL.2"FILM 2 4821 1/4W 470R 5% T&R RES 6 8824 8-32 X 5/16 PAN QUAD TAPTITE SJ500 3 6451 __4N7 250V 20%CAP AC Y ONLY RAD10MM 1 4980 1/4W 470R 5%MINI T&R RES 3 8869 8-18 X 1/2 THRD CUTTING FOR PLASTIC 4 5834 _10N 250V 20%CAP RAD POLYFILM BULK 2 4891 1/4W 620R 5% T&R RES 2 8999 8-32 X 5/8 PAN PH TAPTITE SJ500 17 5210 _22N 100V 10%CAP T&R RADIAL.2"FILM 11 4873 1/4W 680R 5% T&R RES 1 8719 8-32 X 3/4 FILLISTER PHIL MS JS500 2 6435 _22N 275V 20%CAP AC X2 RAD BLK15MM 2 4823 1/4W 1K 5% T&R RES 6 8815 8-32 X 3/4 PAN PH TAPTITE SJ500 5 5308 _47N 50V 10%CAP T&R BEAD X7R 2 4934 1/4W 1K 5% .2"U T&R RES 2 8809 10-32 X 1/4 PAN PH TAPTITE SJ500 4 5226 _68N 100V 5%CAP T&R RADIAL.2"FILM 4 4981 1/4W 1K 5%MINI T&R RES 2 8749 10-32 X 1/2 QDX PH TAPTITE JS500 2 5228 100N 100V 5%CAP T&R RADIAL.2"FILM 3 4854 1/4W 1K2 5% T&R RES 1 8731 10-16 X 5/8 TYPE B HEX W/SLOT JS500 12 5314 100N 50V 10%CAP T&R BEAD X7R 4 4824 1/4W 1K5 5% T&R RES 2 8736 5/16-18X2-3/4 GRD 5 HEX BOLT JS500 1 5229 150N 63V 10%CAP T&R RADIAL.2"FILM 4 4988 1/4W 1K5 5%MINI T&R RES 4 8663 11/64 NYLON SPACER (MICRO PLASTIC) 66 5231 220N 63V 10%CAP T&R RADIAL.2"FILM 2 4791 1/4W 1K54 1% T&T RES 4 8629 10-32 X 1/4 SPACER PHENOLIC 16 5882 220N 250V 10%CAP RAD POLYFILM BULK 4 4808 1/4W 2K 5% T&R RES 4 3746 21/64 X .250 OD #6 SPACER ALUMINUM 2 5255 __1U 63V 20%CAP T&R RADIAL ELE.2" 3 6113 1/4W 2K 5%MINI T&R RES 2 3751 SNAP IN 5/16 SPACER RICHCO 3 5259 __4U7 63V 20%CAP T&R RADIAL ELE.2" 6 4847 1/4W 2K2 5% T&R RES 2 3739 CUSTOM .4 LED SPACER 6 5281 _10U 16V 20%CAP NONPOLAR T&R .2" 2 4804 1/4W 3K 5% T&R RES 4 3743 SNAP ON 0.5" SPACER RICHCO 5 5629 _10U 160V 20%CAP RADIAL ELECT BULK 4 6124 1/4W 3K 5%MINI T&R RES 2 3859 1/2 PLASTIC HEX SPACER #4 2 5945 _10U 63V 20%CAP T&R RADIAL ELECTR 2 6136 1/4W 3K3 5%MINI T&R RES 4 3858 3/4 PLASTIC HEX SPACER #4 4 5260 _22U 50V 20%CAP T&R RADIAL ELE.2" 10 4744 5.0W 3K6 5% BLK RES 8 8667 SHOULDER WASHER SWS-229 LENGTH 1/8 4 5961 _33U 16V 20%CAP NONPOLAR T&R RAD 12 4756 1/4W 4K120 0.1% *** T&R RES 2 8818 3/4 OD X 5/16 ID X .08 THICK WASHER 2 5267 100U 25V 20%CAP T&R RADIAL ELE.2" 3 4681 1.0W 4K7 5% T&R RES 2 3511 #6 FLAT WASHER NYLON 4 5619 330U 100V 20%CAP RADIAL ELECT BULK 4 4827 1/4W 4K7 5% T&R RES 8 8491 #10 SPLIT LOCK WASHER BO 4 5630 330U 25V 20%CAP RADIAL ELECT BULK 6 4943 1/4W 4K7 5% .2"U T&R RES 1 8850 #10 INT TOOTH LOCKWASHER BO 4 5618 470U 25V 20%CAP RADIAL ELECT BULK 1 4982 1/4W 4K7 5%MINI T&R RES 5 3502 NYLON FLAT WASHER OD.158ID.110H.070 2 5896 4700U 80V 20%CAP RADIAL ELECT BULK 16 4887 1/4W 7K5 5% T&R RES 5 3436 DPDT PUSH SW PCMT H BREAK B4 MAKE 3

3587 DPDT ROKR SW QUIK 250" AC/PWR IEC65 1 3705 4P3T SLID SW PCMT H 1 1197 AP4040 T?RD 1

550 Granite Court, Pickering, Ontartio CANADA L1W-3Y8

4625 Witmer Industrial Estate, Niagara Falls, New York USA 14305

SERVICE MANUAL

Yorkville Sound • http://www.yorkville.com

550 Granite Court, Pickering, Ontartio CANADA L1W-3Y8

4625 Witmer Industrial Estate, Niagara Falls, New York USA 14305

SERVICE MANUAL

Yorkville Sound • http://www.yorkville.com

YYoorrkkvviillllee AAPP44004400 PPoowweerr AAmmpplliiffiieerr

MM11112299 ““TTHHEE IINNPPUUTT BBOOAARRDD””

The input board processes the audio signal from the input jacks to the volume control board, (M1128).

Each channel consists of a balanced gain stage, switchable subsonic filter, and a

stereo / mono / bridge switch.

Looking at the left channel, the balanced input, (XLR Jack) and unbalanced input (phone jack) are wired in parallel to the input of a balanced operational amplifier, (U4). The gain of this stage is 0.82 (-1.3dB) balanced and 1.6 (4.0dB) unbalanced. Resistors R25, R27 along with capacitors C11 and C12 form a radio interference elimination filter.

Switch S1 selects the cutoff frequency of the hi-pass subsonic filter.The subsonic filter provides a 20Hz or 40 Hz high pass filter. The filter consists of a tee network on the input of U3 along with R10, R28, C29 and C30, C33 and C34.The gain is 1 (0dB) in the passband, (above 100Hz).

The audio signals from the input board M1129 pass through the 14 conductor cable to board M1128.

MM11112288 ““VVOOLLUUMMEE CCOONNTTRROOLL BBOOAARRDD””

This board contains:

• the front panel audio gain controls

• the front panel indicating LED’s (power, protect, activity and clip).

• the audio limiters

Circuit Explanation:

• The left channel of the circuit is explained. (Refer to the schematic of M1128 as the sections of the circuit are explained.)

The audio signal out of M1129 passes through volume control P2 and the desired level enters U2 through pin 6.U2 is set for a gain of 5 (14dB) when the volume control is in the fully clockwise position.

The AP4040’s defeatable limiter is built around LD8. LD8 is an opto-resistive cell comprising of an LED that shines on a photocell. As the LED in the LD8 becomes brighter, the resistance of the photocell decreases, placing more of the audio signal on pin 5 (non-inverting input) of U2.This audio voltage gets subtracted from the signal on the inverting input and less signal appears on the output of U2.Transistors Q5 and Q6 along with the surrounding passive parts provide the attack and release time constants of the limiting function along with the drive currents for the clip LED and the LED inside LD8.When an audio signal on the output of the power amplifier section (on board M1146) enters clipping, pulses representing the duration of the clipped portion appear at LCLIP.These pulses tur n on transistor Q6, and Q6 provides current pulses to turn on clip LED LD6. The pulses also pass through R7 and D6 to charge C3 and C36.When the voltage across C3 reaches 0.5 volts then Q5 turns on providing a current into the LED of the LD8 limiting the audio signal at U2.The charging (attack) and discharging (release) times of the limiter are 80mS and 3.5 seconds respectively. Resistors R50 and R7 provide the charging path, and resistor R51 provides the discharge path.The limiter can be defeated by placing the limiter switch (S2) in the in position which disconnects Q5 and the charging / discharging circuitry from V+.

The activity LED circuit consists of Q1 and the surrounding circuitry. The audio signal enters the activity LED circuit through R2. R2 and C21 form a differentiator that turns Q1 on illuminating the activity LED whenever the audio signal increases in amplitude. A constant current flows through R55A, R55B and when Q1 is off, the collector current then flows through D1.

From M1128 the audio signal passes through a 12-conductor ribbon cable to circuit board M1147.

On M1127 an operational amplifier U201 re-references the ground for the audio signal from LREF or RREF to the corresponding LOG (left output ground) or ROG (right output ground). U201 also provides DC correction for DC offsets appearing on the output binding posts. Feedback from the output binding posts appears on LFNB or RFNB. Through R203A or R203B the DC offset achieves a gain of -1 from U201.The DC offset of opposite polarity on the output of U201 will compensate for the DC offset in the amplifier section on M1146 resulting in 0 volts DC on the output binding posts.

• The audio signal continues to M1146 via an 8-conductor ribbon cable.

MM11112266 ““TTHHEE VVOOLLTTAAGGEE AAMMPPLLIIFFIIEERR AANNDD CCUURRRREENNTT AAMMPPLLIIFFIIEERR””

This board contains:

• a voltage amplifier section

• a current amplifier section

• amplifier current limit section

• DC output protection

• heatsink temperature sensing

Voltage Amplifier Section

The voltage amplifier amplifies the audio signal’s voltage from 6.8 volts peak (at the output of U201) to approximately 98v peak, which is required to drive the current amplifier section.The current amplifier provides the current required for the 98v peak signal to drive 1200 watts into 4 ohms out of the binding posts.

Before the circuit is described in detail here is a quick rundown on the signal’s path through the voltage amplifier stage.Refer to the schematic of M1146. Let’s consider that a positive going AC signal is present at the SIG input.The positive going signal will turn on the positive side of the voltage amplifier. The signal at the SIG input turns on Q12A (through R40A, D14A and D13A).The collector of Q12A pulls down on the base of Q14A turns this transistor on further and allows a greater current to flow out of Q14A’s collector.This increase in current passes through Q15A and it’s collector to emitter voltage decreases.The collector of Q15A now being more positive in voltage turns the base of Q18A on causing an increase in Q18A’s collector current resulting in test point 1 going positive.

As the positive side of the amplifier was turning on the negative side would have been turning off.This is how test point 1 was able to move positive following the input signal.The reverse would hold true if a negative going signal were present on the input of the voltage amplifier.

550 Granite Court, Pickering, Ontartio CANADA L1W-3Y8

4625 Witmer Industrial Estate, Niagara Falls, New York USA 14305

SERVICE MANUAL

Yorkville Sound • http://www.yorkville.com

CIRCUIT DESCRIPTION:

The voltage amplifier is a mirrored image with circuitry connected to the positive power supply rail being identical (but opposite polarity) to the circuitry connected to the negative power supply rail.

For this reason we will look in detail at the positive side of the amplifier.

The audio signal enters the voltage amplifier at the SIG input.The signal passes through R40A, D14A and D13A to the base of Q12A. Diodes D13A and D14A set up the DC bias on Q12A to approximately 0.6 mA.

The first voltage gain stage consists of Q12A along with the resistor chain on its collector and the emitter resistor (R44A).

Transistor Q12A drives the base of Q14A through the resistor chain. A DC current of approximately 4 mA should flow through the collector of Q14A.The voltage drop across Q14A remains constant and is derived from the voltage drop across the voltage reference Q20A, resistor R58A, and the base/emitter junction of Q15A.This total voltage should equal approximately 3 VDC.Transistor Q14A is the second gain stage and its output current flows through Q15A. Transistor Q15A is a common base stage with the collector driving the base of output buffer Q18A.

Diode D17A is a clamping diode that prevents the maximum peak of the audio signal from coming within 4V of the 144 VDC rail.This is to prevent the output current amplifier from going into saturation during clipping and therefore having storage delay problems.

Transistor Q18A buffers the high impedance present on the collector of Q15A.The output of the buffer provides a low output impedance at the junction of R61A and R62A and is current limited to 30mA through the clamping action of D19A, D20A and D23A. The signal at the junction of R61A and R62A drives the succeeding current amplifier.

Current Amplifier Section

The current amplifier receives a high voltage audio signal from the voltage amplifier and provides the current drive necessary to drive speaker cabinets.

The current amplifier is a two-tier complimentary output driver design controlled by a complimentary darlington stage.

[CIRCUIT DESCRIPTION - REFER TO THE SIMPLIFIED SCHEMATIC #1 ON THE

FOLLOWING PAGE]

550 Granite Court, Pickering, Ontartio CANADA L1W-3Y8

4625 Witmer Industrial Estate, Niagara Falls, New York USA 14305

SERVICE MANUAL

Yorkville Sound • http://www.yorkville.com

QUIESCENT CONDITION:

This design is class A/B and therefore the output driver transistors must be forward biased to provide low crossover distor tion. In most class A/B designs, a diode chain or VBE multiplier is used to control the bias voltage and provide a means of adjusting the bias.This design is different, as there isn’t a diode chain or VBE multiplier. For simplicity lets consider only the positive side of the current amplifier, that is all parts between the positive power supply rails and the audio signal output/input terminals.The negative side is the same as the positive, except for polarity changes.

To bias Q14, greater than 0.5V is needed from base to emitter, (or for simplicity from base to amplifier output). Points A and B are at the same potential, so consider them to be connected. If this is true then 0.5V from test point 2 to the amplifier output must appear across R12.There must be some way of developing this voltage across R12, and there is using the darington (Q5 and Q40) driver along with local feedback.

Simplified schematic #1 shows the biasing circuit.The current needed to develop 0.5V across R12 comes from the emitter of Q5.When the amplifier is first turned on the current source (Q3) turns on Q5 and Q40) and current flows through R12 developing a voltage. When this voltage approaches 0.5V Q1 turns on and robs current from the base of Q40.

550 Granite Court, Pickering, Ontartio CANADA L1W-3Y8

4625 Witmer Industrial Estate, Niagara Falls, New York USA 14305

SERVICE MANUAL

Yorkville Sound • http://www.yorkville.com

550 Granite Court, Pickering, Ontartio CANADA L1W-3Y8

4625 Witmer Industrial Estate, Niagara Falls, New York USA 14305

SERVICE MANUAL

Yorkville Sound • http://www.yorkville.com

This causes Q40 to turn off until the reduced current flowing through Q5 maintains

0.5V across R12. Q1 will turn off slightly causing Q5 and Q40 to increase their collector currents.The circuit reaches a point of equilibrium with approximately 0.5V across R12.

Because all output devices are not identical and base emitter voltages vary, some adjustment must be available to slightly adjust the 0.5V across R12. This is accomplished with RT1. RT1 causes Q1 to turn on slightly more or less resulting in Q5 and Q40 turning on slightly more or less and therefore R12’ s voltage will be slightly more or less than 0.5v. The proper quiescent current voltage is 4mV (to be measured between test points 8 and 9).

The Second Tier and Tier Switching

Refer to the simplified schematic Fig. #1 while reading the following text. One way of making an amplifier more efficient is to vary the Power Supply Voltage on the collectors of the output transistors (Q14 & Q22).The lower the voltage from collector to emitter, the lower the device dissipation. During quiescent conditions, there is 55VDC on the collectors of output transistors Q14 and Q22.The peak AC voltage that can appear on the amplifier’s output is approximately 139V peak. How can an output transistor deliver a 139V peak when its collector is only at 78VDC? It can if its collector is pulled up to 144VDC as the output signal’s peak rises above 78VDC. Refer to Fig.#2. The second tier voltage must remain above the amplifier’s output voltage by amount Vm. Therefore the circuitry controlling the second tier voltage must increase the tier voltage before the amplifier’s output voltage reaches 78VDC.This leading voltage is necessary to compensate for time lag of the second tier circuit during fast rising amplifier output

signals.

The voltage between the amplifier’s output and test point 4 is approximately 12VDC derived from the voltage drop across ZD4.We call this voltage the “floating battery” because it floats on top of the output audio signal with test point 4 always being 12VDC greater than the peak of the output signal.Test point 4 drives the gate of mos-fet Q11. Q11 controls the transistors of the upper tier.As Q11 tur ns on its source forward biases the base of Q13 and Q13 pulls the collector of Q14 towards the 100 volt rail. The gate to source voltage needed to turn on Q11 is approximately 3.5 volts. When the peak output signal is about 69.5vp (78v-(12v-3.5v)) then Q11 will start to turn on the second tier. The second tier voltage will remain about 13 volts (Vm) above the peak of the output signal

to the point of clipping where this voltage is reduced to about 6 volts (measured driving an 8 ohm load). Zener ZD8 protects the gate source junction of Q11 and also provides a supply current path through R29 for the “floating battery”.

NOTE: The Power supply voltages given are those when the amplifier is not dr iving a

speaker load.This will allow yo to check the tier switching with the cover of the amplifier off and the amplifier, therefore, running cool.

Current Limit Protection Circuitry

To have an amplifier drive 3000 watts into practically any combination of speaker cabinets and know what is a safe load and what is not is a very difficult task. An extensive

amount of time was spent on the current limit circuitry so that it may simulate the safe operating area of the output transistors (SOAR curve).No matter how reactive the load may be the phase shift that it presents, along with it’s resistive component is used to set the output current limit of the output transistor stage.

Refer to the schematic of board M1146 while reading the following text.The current limit circuitry is a mirrored image with circuitry connected to the positive power supply rail being identical (but opposite polarity) to the circuitry connected to the negative power supply rail.For this reason we will look at the positive side of the circuitry.

Transistor Q9 measures the peak current flowing through resistor R53. The voltage across R53 (as a result of the current flowing through it) is scaled down by R55, R35, R35A, R36, R37, D7 and D11 these parts make up the safe operating area along with the time constants of C30, R34, C12 and R26. Fig. #3 shows a waveform of the current that passes through R52 and R53 when the output of the amplifier is shor ted to ground. This can only be seen by using an oscilloscope to measure differentially across R52 and R53.The conditions of the measurement are contained on the diagram. During current limit when Q9 turns on it reduces the voltage across R42. R42 is in series with a 16 volt zener (ZD7) and is also in parallel with the junction of Q8.The current that flows through R20, ZD7, R42, and R22 normally saturates Q8. When Q9 reduces the voltage across ZD9 and R42 to below 16.6 volts, Q8 turns off allowing a charge to build up on C8 through resistors R24 and R25. If current limiting occurs for a long enough duration to allow C8 to charge to 1.2 volts then Q7 will turn on tripping the relay circuit on board M1147. As soon as the relay is tripped the audio signal will be turned off at the output of the voltage amplifiers and will remain off for about 5 seconds before the relay turns on and allows the audio signal to pass through the amplifier.If a current limit condition is still present then the whole cycle will occur again and repeat until the load conditions on the amplifier’s output are safe for the amplifier.When a safe load appears the amplifier will automatically reset and drive that load (the speaker cabinet).

DC Protection

If a DC voltage greater than 8 volts appears on the output of the amplifier for more than 200 milliseconds then triac Q30 will turn on holding the output at ground potential. MBS4992 is a device that turns on at either + or - 8 volts DC.

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4625 Witmer Industrial Estate, Niagara Falls, New York USA 14305

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NOTE: Every time you replace blown output transistors on a

M1146 board test the DC protection triac with the following circuit.

Conditions of test:

A) Pass a 100Hz 25v peak signal through the M1126 board under test with no load connected to the amplifier output.

B) Connect points 1 and 2 as shown in the diagram.The amplifier should go into protect mode as the triac (if working) shorted the output of the amplifier to ground, and the amplifier goes into current limit.

C) Disconnect the triac test circuit and allow the amplifier to complete it’s protect cycle. D) Reverse connections 1 to 2 and 2 to 1 and test again.The same results as in B)

should be observed if the triac is working.

Only test the triac for one protect cycle as

prolonged testing will heat the triac to a high temperature.

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• The shutdown relay and its associated drive circuitry have two possible operating states.

• Amplifier on under normal operating conditions.

• Amplifier power switch has just been turned OFF/ON, or the amplifier is in current limit protecting the amplifier’s output transistors, or the amplifier has overheated.

Shutdown Circuit

Here is how the circuit accomplishes these functions.The relay’s normally closed contacts short the output of the voltage amplifiers to ground when the power switch is off. When the power switch is turned on, the relay remains off (normally closed) for about 6 seconds. C203 charges to 35V and results in Q203 turning off allowing Q201 to turn on. As Q201 turns on, it connects the negative terminal of the relay’s coil (Pin 16) to ground energizing the relay and opening the normally closed contacts.

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If prolonged current limiting occurs on the amplifier’s output transistors then D204 or D205 (depending on which channel is current limiting) will be forward biased turning on Q202 (from its off state). Now +144VDC appears on the collector of Q202 and through R210 and R211 turn on Q203 therefore turning off Q201 by shorting its base emitter junction. Q201 turning off will turn the relay off and the normally closed contacts (off state) will short the outputs of the voltage amplifiers to ground so as not to continuously stress the amplifier’s output transistors.A cycle now occurs. With the voltage amplifiers now disabled there is no signal driving the output transistors (Q13 to Q28).

The current limit circuit protecting the output transistors (Q13 to Q28) turns off and D204 and/or D205 are not forward biased and Q202 turns off.Through Q203 and Q201 the relay is turned back on and the voltage amplifiers are now active again, driving the output transistors. If current limiting still occurs, then the same cycle will occur. If the cause of current limiting (low impedance or short on the speaker output terminals) has been removed, then the amplifier will continue to operate normally.

The third operation that the relay provides is “overheat shutdown”.If for some reason the fan cannot keep the heatsinks in a safe operating temperature area then the fan control circuit (on board M1147) will deliver through D207 a positive current to turn Q203 on and turn Q201 off to turn off the relay and disable the voltage amplifiers. When the fan has cooled down the temperature of the amplifier, then the signal through D207 will disappear and the relay circuit will turn on the relay to resume normal operation. Anytime the relay is in the “protect” mode (due to the abnormal states) then contact pin 4 of the relay will illuminate LD3 (the protect LED on the front panel).

Soft Turn On Circuit

To reduce the “inrush” current that flows through the line cord from the 120 VAC power source (typical with large linear power supplies), a circuit provides a soft turn on function.When the power switch is turned on, the current that initially flows through the primary of the transformer must flow through SG201 and SG202.These are surgestors that reduce the peak inrush current flow.After about 500 milliseconds a relay’s contacts short across the surgestors so that they are not stressed by the current flowing through them under normal operation. A circuit consisting of Q240, Q241, C215, and the associated resistors provides the time delay for the turn on cycle of the relay. The circuit is very similar to the shutdown time delay circuit.Refer to the section on the shutdown circuit for a circuit description.

Fan Circuit

Looking at the schematic to board M1147, here is a quick explanation of the fan control circuit.There is a temperature sensor (AS35) on each M1146 board.When the amplifier is first tur ned on, Q207 and Q208 are off.The AS35 temperature sensors are configured as temperature controlled current sources. As either temperature sensor begins to heat up, more current flows through D212 or D218 increasing the voltage drop across R235 or R236. The hotter temperature sensor will provide more current than the cooler sensor and therefore develop a higher voltage across it’s associated 8K2 resistor.The higher voltage will forward bias D212 or D218 reverse biasing the cooler temperature

sensor’s diode so that the hotter sensor will control the fan speed. At 40 degrees C there

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is 10 volts across R235 or R236 which is enough to turn on Q210, Q208, and Q207 pro-

is 10 volts across R235 or R236 which is enough to turn on Q210, Q208, and Q207 providing 7 DC volts to the fan. Further heating the temperature sensors results in a larger

viding 7 DC volts to the fan. Further heating the temperature sensors results in a larger

viding 7 DC volts to the fan. Further heating the temperature sensors results in a larger DC voltage across the fan.To lower the dissipation of Q207, D215, D216, ZD205, ZD206

DC voltage across the fan.To lower the dissipation of Q207, D215, D216, ZD205, ZD206

DC voltage across the fan.To lower the dissipation of Q207, D215, D216, ZD205, ZD206 and R226 turn off Q207 and Q208 when the full wave rectified voltage present of the col-

and R226 turn off Q207 and Q208 when the full wave rectified voltage present of the col-

and R226 turn off Q207 and Q208 when the full wave rectified voltage present of the collector of Q207 reaches approximately 58V by robbing current from the base of Q208.

lector of Q207 reaches approximately 58V by robbing current from the base of Q208.

lector of Q207 reaches approximately 58V by robbing current from the base of Q208. The maximum fan voltage is 20.5 VDC. ZD207 and R228, R229 and R230 provide a cur-

The maximum fan voltage is 20.5 VDC. ZD207 and R228, R229 and R230 provide a cur-

The maximum fan voltage is 20.5 VDC. ZD207 and R228, R229 and R230 provide a current limiting function. Figure #4 shows the current through these resistors when there is

rent limiting function. Figure #4 shows the current through these resistors when there is

rent limiting function. Figure #4 shows the current through these resistors when there is 12VDC across the fan.

12VDC across the fan.

Thermal Shutdown Circuit

The emitter of Q210 in the fan circuit is the measuring point for the shutdown voltage.

The emitter of Q210 in the fan circuit is the measuring point for the shutdown voltage. As the temperature sensing devices (AS35) that control the fan circuit heat up the volt-

As the temperature sensing devices (AS35) that control the fan circuit heat up the volt-

As the temperature sensing devices (AS35) that control the fan circuit heat up the voltage on the emitter of Q210 rises until at 85 degrees Celsius on the M1146 heatsinks.

age on the emitter of Q210 rises until at 85 degrees Celsius on the M1146 heatsinks.

age on the emitter of Q210 rises until at 85 degrees Celsius on the M1146 heatsinks. The voltage on the emitter of Q210 reaches 18 (85 degrees C) VDC and the amplifier

The voltage on the emitter of Q210 reaches 18 (85 degrees C) VDC and the amplifier

The voltage on the emitter of Q210 reaches 18 (85 degrees C) VDC and the amplifier must be shutdown to protect the output power transistors. ZD202 and D207 become

must be shutdown to protect the output power transistors. ZD202 and D207 become

must be shutdown to protect the output power transistors. ZD202 and D207 become forward biased and Q203 turns on turning the relay off and muting the audio signal.

forward biased and Q203 turns on turning the relay off and muting the audio signal.

forward biased and Q203 turns on turning the relay off and muting the audio signal. After the amplifier cools down the voltage will decrease until Q37 turns off turning the

After the amplifier cools down the voltage will decrease until Q37 turns off turning the

After the amplifier cools down the voltage will decrease until Q37 turns off turning the relay back on enabling the amplifier.

relay back on enabling the amplifier.

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STEP 1: VISUAL INSPECTION OF FRONT PANEL AND FAN

• Check to see whether the green power LED is lit. If not, the amplifier has a

• Check to see whether the green power LED is lit. If not, the amplifier has a power supply (M1147 board), transformer, A.C. switch or line cord problem.

power supply (M1147 board), transformer, A.C. switch or line cord problem.

• If the red protect LED stays on or samples off and on, this usually indicates a

• If the red protect LED stays on or samples off and on, this usually indicates a problem with the voltage amplifier or current amplifier sections on one or both of

problem with the voltage amplifier or current amplifier sections on one or both of

problem with the voltage amplifier or current amplifier sections on one or both of the M1126 boards. Check for misaligned pin connections or see if the ribbon

the M1126 boards. Check for misaligned pin connections or see if the ribbon

the M1126 boards. Check for misaligned pin connections or see if the ribbon cables have been cut or pinched through their insulation.

cables have been cut or pinched through their insulation.

• If the fan is running at full speed at power up this usually indicates a problem

• If the fan is running at full speed at power up this usually indicates a problem with the fan circuitry on the M1147 board, but it can also be caused by M1146 cir-

with the fan circuitry on the M1147 board, but it can also be caused by M1146 cir-

with the fan circuitry on the M1147 board, but it can also be caused by M1146 circuit problems. A damaged AS35 temperature sensor located under the M1146

cuit problems. A damaged AS35 temperature sensor located under the M1146

cuit problems. A damaged AS35 temperature sensor located under the M1146 heatsinks can cause erratic fan behavior.

heatsinks can cause erratic fan behavior.

• No output on either or both channels could be caused by intermittent push

• No output on either or both channels could be caused by intermittent push switches on the input board.

switches on the input board.

STEP 2: VISUAL INSPECTION OF INTERNAL CHASSIS AND INITIAL TESTING

After removing the lid, look for any signs of smoke, charring or burnt components.

After removing the lid, look for any signs of smoke, charring or burnt components. Before powering up replace the burnt components, and check the associated circuitry

Before powering up replace the burnt components, and check the associated circuitry

Before powering up replace the burnt components, and check the associated circuitry for damaged parts. Disconnect one M1127 board and test one board at a time to

for damaged parts. Disconnect one M1127 board and test one board at a time to

for damaged parts. Disconnect one M1127 board and test one board at a time to reduce the possibility of further damage. Use a variac to slowly increase the 120 VAC

reduce the possibility of further damage. Use a variac to slowly increase the 120 VAC

reduce the possibility of further damage. Use a variac to slowly increase the 120 VAC up from 0 volts while monitoring the quiescent current with a meter and the speaker

up from 0 volts while monitoring the quiescent current with a meter and the speaker

up from 0 volts while monitoring the quiescent current with a meter and the speaker output with an oscilloscope. Watch the speaker output for large DC offsets, or oscilla-

output with an oscilloscope. Watch the speaker output for large DC offsets, or oscilla-

output with an oscilloscope. Watch the speaker output for large DC offsets, or oscillation. Watch the meter for large collector currents flowing. Remember under quiescent

tion. Watch the meter for large collector currents flowing. Remember under quiescent

tion. Watch the meter for large collector currents flowing. Remember under quiescent conditions, there should only be 3 to 5 millivolts across test points 8 and 9 on the out-

conditions, there should only be 3 to 5 millivolts across test points 8 and 9 on the out-

conditions, there should only be 3 to 5 millivolts across test points 8 and 9 on the output stage of the amplifier.

put stage of the amplifier.

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SPECIFICATIONS

Frequency Response: +/- 1dB, 20 Hz to 20 KHz

Hum and Noise: -103 dB below max output RMS voltage, unweighted

THD (1 khz, 4–Ohms): <0.01%

THD(20Hz – 20kHz, 4–Ohms): <0.1%

High Pass Filter: 40Hz, 12 dB/octave

Slew Rate: Power amp section: 25 V/uS, 50 V/uS in bridged mode

Damping Factor: > 600, 20 Hz - 20 KHz, into 8 ohms

Crosstalk: -75 dB below full output at 1khz, -60 dB below full output

(20 Hz - 20 KHz)

Input Impedance: 20 KOhms balanced, 10 KOhms unbalanced

Input Sensitivity: 1.4 VRMS sine wave

(AP4020: 36 dB, AP4040: 39 dB gain)

Rejection: CMRR@60Hz: minimum 48dB, typical 56dB

Controls: Rotary GAIN controls, MONO/STEREO/BRIDGE,

FILTER and LIMITER switches

Displays: 2x CLIP, 2x ACTIVITY, PROTECT, POWER ON (LEDS)

Input Connectors: 2x XLR, 2x 1/4” phone (TRS)

Output Connectors: 2x Binding Post, 3x Speakon™ SP-4

Turn On/Off transients: < 15 milliwatt / seconds, 0.5 Wpk. (1s on delay)

Power Consumption: Typ 1130, Max 1800 Watts

Transformer: Toroidal

Protection: Fully protected: DC, LOAD and THERMAL

Cooling: Aluminum Heatsinks with DC servo–controlled fan (in front, out rear)

Size: (DWH) 44 cm x 48 cm x 9 cm (front panel to binding posts)

(DWH) 17.5 in x 19 in x 3.5 in Two rack spaces

Weight: 43.5 pounds, 19.8 Kilograms

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550 Granite Court, Pickering, Ontartio CANADA L1W-3Y8

4625 Witmer Industrial Estate, Niagara Falls, New York USA 14305

550 Granite Court, Pickering, Ontartio CANADA L1W-3Y8

4625 Witmer Industrial Estate, Niagara Falls, New York USA 14305

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