M648 — Power Supply

The M648 plug-in regulated power supply is designed primarily for use in WBS consoles and systems The unit provides 48V dc 1A regulated output and an auxilliary 24V unregulated output for relay/lamp operation. The low internal impedance permits the operation of multiple amplifiers within system from a common power source without crosstalk or noise interaction: FEATURES: Dual Supply 48V Regulated plus 24V relay /lamp power Over-voltage and automatic current limit The standard model features current limit and over-voltage protection.

The current limit is electronically activated in the presence of a short or excessive current demand and is automatically restored when normal Ioad conditions are resumed. Convenient front panel controls and fuses Conditional strapping is accomplished on the frame receptacle to achieve either local or remote sensing: In the latter mode the comparison circuitry is referred to a selected external distribution point to eliminate the effects of signal coupling due to lengthy common power leads: Active elements on plug-in P.C.

card The active circuit elements are contained on subsidiary plug-in P.C. board for maximum flexibility and convenient unit interchange. To further simplify maintenance , the series regulator power device is mounted utilizing an insulated chassis socket: Encapsulated reference amplifier for excellent temperature stability The modest size of 3.4W x 3.4H x 13.7D inches allows 'five M648 power supplies to be accommodated in one standard rack mounting 19W x 3.5H) MF6 equip- ment frame.

Perforations assure adequate vertical ventilation by natural convection of air through the modules: Convection cooled

The M648 plug-in regulated power supply is designed primarily for use in WBS consoles and systems The unit provides 48V dc 1A regulated output and a auxilliary 24V unregulated output for relay/lamp operation. The low internal impedance permits the operation of multiple amplifiers within a system from a common power source without crosstalk or noise interaction. FEATURES: Dual Supply 48V Regulated plus 24V relay /lamp power Over-voltage ad automatic current limit The standard model features current limit ad over-voltage protection.

The current limit is electronically activated in the presence of a short or excessive current demand ad is automatically restored when normal load conditions are resumed, Convenient front panel controls and fuses Conditional strapping is accomplished on the frame receptacle to achieve either local or remote sensing: In the latter mode the comparison circuitry is referred to a selected external distribution point to eliminate the effects of signal coupling due to lengthy common power leads_ Active elements on plug-in P.C.

card The active circuit elements are contained on a subsidiary plug-in P.C. board for maximum flexibility and convenient unit interchange. To further simplify maintenance the series regulator power device is mounted utilizing an insulated chassis socket: Encapsulated reference amplifier for excellent temperature stability The modest size of 3.4W x 3.4H x 13.7D inches allows 'five M648 power supplies to be accommodated in one standard rack mounting ( 19W x 3.5H) MF6 equip- ment frame Perforations assure adequate vertical ventilation by natural convection of air through the modules Convection cooled

The M648 plug-in regulated power supply is designed primarily for use in WBS consoles and systems The unit provides 48V dc IA regulated output and an auxilliary 24V unregulated output for relay /lamp operation The low internal impedance permits the operation of multiple amplifiers within a system from a common power source without crosstalk or noise interaction. FEATURES: Dual Supply 48V Regulated plus 24V relay /lamp power Over-voltage ad automatic current limit The standard model features current limit ad over-voltage protection The current limit is electronically activated in the presence of a short or excessive current demand and is automatically restored when normal load conditions are resumed: Convenient front panel controls and fuses 'Conditional strapping is accomplished on the frame receptacle to achieve either local or remote sensing: In the latter mode the comparison circuitry is referred to a selected external distribution point to eliminate the effects of signal coupling due to lengthy common power leads Active elements on plug-in P.C.

card The active circuit elements are contained on a subsidiary plug-in P.C. board for maximum flexibility and convenient unit interchange To further simplify maintenance , the series regulator power device is mounted utilizing a insulated chassis socket; Encapsulated reference amplifier for excellent temperature stability The modest size of 3.4W x 3.4H x 13.7D inches allows 'five M648 power supplies to be accommodated in one standard rack mounting (19W x 3.5H) MF6 equip- ment frame.

Perforations assure adequate vertical ventilation by natural convection of air through the modules Convection cooled

REGULATED OUTPUT VOLTAGE 48 volts dc LOAD CURRENT 0 to 1A (Refer to applications notes when operating continuously more than 600 mA for recommended rack spacing) . LINE REGULATION 0. % for line variations between 105 and 125 volts LOAD REGULATION 0.1 % for load variations between 0 and 1A RIPPLE AND NOISE Less than 500 micro-volts rms for all line and load conditions specified above INTERNAL IMPEDANCE Less than 0.05 ohm dc to 20 kHz STABILITY 0.1 volts measured over an 8 hr.

period, after 30 mins warm-up REMOTE SENSING Terminals provided PROTECTION Electronic current limit and over-voltage circuits UNREGULATED OUTPUT 2 VOLTAGE 24 volts dc + 10% with 115 line volts LOAD CURRENT 0.5A maximum RIPPLE Less than 1.5 volts rms at 0.5A load current GENERAL PRIMARY POWER REQUIREMENTS 105 to 125 volts ac 6OHz 100 VA maximum AMBIENT TEMPERATURE 0"to 60'c DIMENSIONS 3.4W 3.4H x 13.7D inches WEIGHT 8 Ibs net ACCESSORIES: MF6 600 Series Mounting Frame.

19W x 3.5H x 14.5D (less rear cable tray and cover) Standard EIA rack mounting: Accommodates five M648 modules or any combination of single, double or quadruple units not exceeding ten single width modules. MFR6 600 series Frame Receptacle. Two required per M648 WARD-BECK SYSTEMS LTD; WARD-BECK SYSTEMS INC, 841 Progress Ave,Scarborough, Ont M1H 2x4 290 Larkin St;, Buffalo; New York 14210 Telephone: (416) 438-65SO Telex: 06-23469 WBS

REGULATED OUTPUT VOLTAGE 48 volts dc LOAD CURRENT 0 to 1A (Refer to applications notes when operating continuously more than 600 mA for recommended rack spacing) . LINE REGULATION 0.1% for line variations between 105 ad 125 volts LOAD REGULATION 0.1% for load variations between 0 and 1A RIPPLE AND NOISE Less than 500 micro-volts rms for all line and load conditions specifi fied above INTERNAL IMPEDANCE Less than 0.05 ohm dc to 20 kHz STABILITY 0.1 volts measured over a 8 hr.

period, after 30 mins warm-up REMOTE SENSING Terminals provided PROTECTION Electronic current limit ad over-voltage circuits UNREGULATED OUTPUT 2 VOLTAGE 24 volts dc + 10% with 115 line volts LOAD CURRENT 0.5A maximum RIPPLE Less than 1.5 volts rms at 0.5A load current GENERAL PRIMARY POWER REQUIREMENTS 105 to 125 volts ac 6OHz 100 VA maximum AMBIENT TEMPERATURE 0?to 60'c DIMENSIONS 3.4W x 3.4H x 13.7D inches WEIGHT 8 Ibs net AcCESSORIES: MF6 600 Series Mounting Frame.

19W x3.5H x 14.5D (less rear cable tray ad cover) Standard EIA rack mounting: Accommodates five M648 modules or any combination of single, double or quadruple units not exceeding ten single width modules. MFR6 600 series Frame Receptacle. Two required per M648 WARD-BECK SYSTEMS LTD_ WARD-BECK SYSTEMS INC_ 841 Progress Ave,Scarborough Ont M1H 2x4 290 Larkin Sc;, Buffalo, New York 14210 Telephone: (416) 438-6550 Telex: 06-23469 WBS

GAIN 50 7OdB Transducer FREQUENCY RESPONSE + 0.25dB from 2OHz to 20kHz (greater than ~3dB at 35kHz) EQUIVALENT INPUT NOISE -126dBm (1OHz to 1OOkHz bandwidth) _128dBm (1OHz to 20kHz bandwidth) TOTAL HARMONIC DISTORTION Less than 0.25% from 3OHz to 20kHz, Less than 0.5% from 2OHz to 20kHz (Measured at + 3OdBm output level) SOURCE IMPEDANCE 150/600 ohms balanced or unbalanced INPUT IMPEDANCE Greater than X 10 source impedance INPUT LEVEL ~6OdBm nominal, ~2OdBm maximum LOAD IMPEDANCE 150/600 ohms balanced or unbalanced OUTPUT IMPEDANCE Less than 1/5 load impedance OUTPUT LEVEL + 30dBm (1 watt) maximum PHASING The low terminal number of the input pair ad the low terminal number of the output pair are in phase POWER REQUIREMENTS 48 volts dc, reg.

from M648 or equiv. 1OOmA at watt output level AMBIENT TEMPERATURE 0? to 608c DIMENSIONS 1.WW x 3.4H x 13.70 inches WEIGHT 4 Ibs net ACCESSORIES: MF6 600 Series Mounting Frame: 19W x 3.5H x 14.5D (less rear cable tray and cover) . Standard EIA rack mount ting: Accommodates ten M6OO modules or ay combination of single, double or quadruple units not exceeding ten single width modules.

MFR6 600 Series Frame Receptacle. One required per M6OO. WARD-BECK SYSTEMS LTD_ WARD-BECK SYSTEMS INC; 841 Frogress Ave_Scarboragh, Ont_ MH 2x4 290 Larkin S_ Buffalo; New Yok 14210 Telephone: (416) 438-6550 Telex: 06-23469 WBS

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T he constant current sourc e Q2 isol ate s the incremental changes of the unr el ulat ed de input vol tai c f rom the co ntrol current leav in,lhe eoll eet or ofQ 4 a nd enle r inl the base of Q3.

Q3 is a current amplifier desi lned to driv e Ihe series pass po wer tran sist ar Q I on t he mai n frame assembly of t he M641 or M641A.

Q4 is a le vel shi ft er which shifts th e output volt aIc f rom Ihe re lu lat or U l fr om +24 volts to +43 vei n ,

UI co nta i ns a nominal 1.7 volt pr eci sion ref er ence a nd compari soo amplif ie r. T he compar ison voll a,e appca ri nl ll pin 6 0f VI is derived fr om the samp1inl volt age di vid er cODsiu inl of RU. RI4 and RIS . Ad jun ment of R I4 is used t o set t he outp ut vcteage to exa ctly +4& volt s. UI derives ilS supply voltage fr om the +4g volt regu- late d out pu t via vollage d ivi de r R& a nd R9. appearingatpins2Ud30fthelC.

Th e sampJinl voltaic divider RU through to RIS ma y be effectivel y ext end ed 10 a remote load via the se nsing volta ic terminals II pin s 9 and 7 of t he SA14- 0S1 assembl y. Thi s remote sensing f eature is to maintain consta nl load volta, es f or load s rem ote from the power supply (ref er to drawing B 641-02 ·003 (M641) or B641-02·ooS (M64&A) for int er conn ecting detail).

R I2 a nd RI6 arc effectively short ed out by the interconnect in g lead s from th e sense termin alS and 1000d terminals. In the event that the sense lead s become di s- conne cted. the power supply's ref er ence d iv ider network is st ill all owed to sam ple the +4& VOlt output throu gh tho se resi sto n prev entinl possible f ailures to th e ' upply or th e load .

Q I monitors t he out put load current by sensing th e voltag e drop across th e resistor betwe en pi ns I and 3 on the re gulator card: R 3 on drawing B 64&-02-002 (M64&) or B 64 &-02-004 (M64IA) . When the supply current appr oaches I.S amp s. Q l begin s to con duct, which in turn decreases th e conduction of curr ent saur ce Q2, curre nt limitin g the ser ies regulator. Thi s re duce s the regul ated output voltag e wh ich reduces th e rev er se bias applied to Ql set by R4 a nd R7 permitting Q l to cond uct " hard er. Th is regenerative pr ocess reduce s bath output volta ge and curre nt th er eby reducin l th e power di ssipation in th e series regulator dur in g any ov erlo ad cond it- ion s.

Ove r volta ge pr ot ection is ef fe cted by the cr owbar circuit consisti ng of SCR CR4 an d een er diod e CR3. lr r ar an y r eason the output voltage ri ses a bove +S6 vern , a .c

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RS To SERIES PASS 13 TRANSISTOR BASE (01) UNREGULATED VOLTAGE 03 TN2102 CRI IN746B 3.3V R2 3k3 711 +48V CR3 INLZ58B 56v Tzk /2w 820 1/2w 8k8 R38 TN337 +SENSE Tn2102 BiK 3 Rok R3 4K7 R18 270 To CROWBAR RESISTOR (RI) 209895 C6 1/100 CR2 NLO03 C3 4700p R2O TN2102 R14 500 LM37GN C2 2200p 220/63 C8 22/35 R1S 1K8 10K 3.75w 270 ~SENSE R6 4K7 /2W R9 2K2 3.75w RII 6K8 R16 150 R19 10k 2.2/35 4.7/35 4.7/35 INPUT COMMON outPut COMMON NOTES: ALL RESISTORS ARE 1/4w5% AND ALL CAPAC ITORS ARE IN UF UNLESS OTHERWISE SPECIFIED . LAST COMPONENT DESIGNAT IONS: c8,CRL 04, R2O U1 _ WHEN USED FOR REPLACEMENT M648 POWER SUPPL IES PRIOR To JANUARY 983 ADD 0.047 UF CAPACITOR To SERIES PASS TRANSISTOR ON MA IN FRAME _ WBS WARD-BECK ByBTeMB SA14-058 REGULATOR ASSEMBLY SCHEMATIC 14-058-02-001 ISS -

620 R5 12K 4/2w R1O 6k8 6K8 WBS RII 450 R1Z fik CANADA R13 R1? JOK 14-058 C8 C6 22/35 1/100 TN?to2 TN?oz 820 1/2w R8 4KZU/2w R6 T9837 C3 4700p TNZ102 C1 7735 cs 7/35 R9 2K2 3-25w R3 4K? R2 3K3 CRI JN7468 3. 3V 270 RI 1OK 3,75W INLOO3 CR2 LM376N 2200p CRJ _JNL7S8B/ 270 R18 R19 JOK Rzo 51 R16 150 Bo6 R1S 1K8 fL 2/35 220/63 C7 CR4 2N6395 WBS WARD-BECK ByBTEMB SA14-058 REGULATOR ASSEMBLY COMPONENT LAYOUT B 14-058-06-001 ISS

m648_POWER_SUPPLY The M648 power supply plugs directly into the MF6 mounting frame The frame may be installed standard EIA nineteen inch equipment rack using the hardware supplied with the rack . The MF6 frame normally furnished with full guide comp lement order accept maximum five M648 power supplies any combination single multiple width modules not exceeding ten single width modules the mounting frame has been procured less receptacles these may first installed the appropriate module positions Note that the receptacle containing the ac line voltage connections inverted This has been done provide the mechanical polarizing necessary prevent inadvertent insertion other com- panion modules which not operate from the ac Iine.

iwo Where vertical rack space permits and the ultimate noise and crosstalk desired recommended allocate only modules the same type each individual MF6 rack frame Ideally, when system planning permits, all ac powered regulated supplies should located at the bottom the equipment rack and only the power distribution need be wired the designated amplifier components via appropriate conductors necessary provide power audio amplifiers with the power supply and amplifiers installed the same frame the power supply should be positioned the right side the frame (normal practice viewed from rack front) and the amplifiers located the extreme left _ Jumper terminals P2,12 (chassis ground) all power supplies common frame together and connect #18 AWG wire from each frame power supplies the systems ground bus Make separate connection from erminals P2,10 and each power supply the systems ground bus Determine the voltage distribution (zero reference point) be from the frame receptacle from some remote location terminal block rack console system) _ In the case distributing the volt common and the +48 voits directly from P2 receptacle, jumper the appropriate sensing leads the frame receptacle (ie.

jumper terminals P2,9,10 and and terminals P2,1,2 and 3) _ 4joz 70 wbiv Mottob T34302 9oteizmaAt 9ot3bJJOJ 0o4iFaO 3248 3-1

M468 POWER SUPPLY c) M136 or R14 on the SA14-058 assembly for Adjust R9 on the an output voltage of 48V +/ - V output ripple and noise voltage with the an ac Measure HP 4OOFL) - It should be less than 500 voltmeter (such as an microvolts rms 5 _ a) the ac voltmeter connected as outlined above connect With 48 ohm 200 watt load resistor to the V1 output terminal _ b ) and noise voltage should remain below The output ripple 500 micro volts rms c) ac voltage between 105 and 125V_ Confirm Vary the primary voltage remains at 48 volts +/ - 0.048 volts that the output (0.1 % regulation) 6 the short circuit characteristics of the 48 volt To determine it is necessary to connect 50 ohm rheostat regulated supply (with of 200 watts or greater) in series with an wattage ammeter as load for the power supply_ a) Slowly reduce the resistance of the load _ Observe that at Ioad current of approximately 1 .25 amps the regulator should begin to g0 out of regulation and the output voltage will begin to drop b ) Continue decreasing the load resistance to (the only load at this point is the internal impedance of the ammeter) The load current should drop to less than 0.5 amps and the output voltage should be 0 .

c) When the short is removed the output voltage should rise to 48 volts and go into regulation. To check the over voltage crow bar protection set up the power supply as follows_ a) Replace F2 with amp slow blow fuse_ b ) Connect the power supply to the ac power source through variac_ (set to output) Page of

M648 POWER SUPPLY Reference M648 Manual Check the module for correct assembly with special attention given to the following: a) Check that the "high" side of the AC Iine input is connected between P1-7 and the end terminal of F1 (not the front ring) b ) Check that filter capacitors C2 and C3 are wired for the correct polarity. The positive terminal should connect to the rectifier cathode c) Confirm the correct connections to series pass transistor Q1 _ Note: Where SA14-028 regulator assembly has been procured for replacement of the M136 assembly , it is necessary to install 0.047 mfd/400 volt decoupling cap- acitor between the base and collector of series pass trans_ istor Q1 _ d) Ensure that all fuses are the correct types (fast blow or slow blow) and sizes 2 a) Install series pass transistor 01 (2N4347) b ) Install the M136 or SA14-058 regulator card_ 3 _ a) With dc voltmeter connected across the VI output of the jig (no load) slowly apply primary ac power through variac.

b ) The regulator should begin regulating at an output voltage of 54 volts or less The dc output voltage should stop increasing even when the primary ac Iine voltage is increased to 115V_ If the regulator does not become operative at the output voltage specified above stop increasing the primary ac voltage. Trouble shoot the regualtor card assembly Refer to the voltage chart supplied in the manual for the M136 or 5A14-058 assembly for guide Iines, Page of ISSUE APRIL/83

M648 POWER SUPPLY c) Connect shorting jumper between collector and emitter of series pass transistor 01 d) Remove the load resistor from the 48 volt dc output leaving only dc volt meter connected_ e) Slowly raise the primary ac voltage while observing the dc volt meter across the output _ At approximately 54 to 58 volts the SCR crow bar will fire shorting the output of the power supply (dc voltage drops to Ov ) f) Very quickly reduce the primary ac voltage.

9 ) Remove the shoring Iink around Q1 and install the fast blow fuse in F2 _ amp h) Re-apply the prit mary ac voltage and establish that the 48 volt output is correct and regulating 8 a) Measure the 24 volt unregulated output noting that this voltage is between 22 and 26 volts for prie mary ac voltage of 115 volts b ) With 48 ohm, 200 watt load connected, load current of approximately 0.5 amps should result with an output ripple voltage of nominally 1.SV rms.

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