Philips DV29 service manual Arcam

Transformer Specification for 115/230V 50/60Hz mains transformer.

Arcam Part Number L924TX

The transformer is extremely cost sensitive. It is to employ the most cost effective techniques to achieve the specification.

The transformer output voltage will be regulated by a switch mode power supply.

The only essential specification is the fact that it must produce no acoustic noise either internally or by induced eddy currents in steel chassis etc..

All other specifications are negotiable in the interest of allowing cost reduction. Even the use of a frame TX rather than a toroid is negotiable providing it is silent.

1. The transformer MUST be silent when loaded to Po +10% and when supplied from Vin = 270V r.m.s.

General Safety specification.

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2.To standards BS415 / EN60065 - Class I / EN60742

3.Transformer to be used in equipment which will be sold worldwide and certified to CE, CB, UL and CSA Standards. All materials etc to be adequate for worldwide safety approvals.

Material Safety Specification

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4.Winding Wire to be Grade 2 (130°C rating) to BS 60317-4 1995

5.Mylar Polyester Insulator Rated to 130°C

Electrical Specification

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6.Transformer to have dual 115V primaries to allow parallel operation for 115V input and series operation with 230V input.

7.Transformer is required to provide a mains isolation barrier and provide a single secondary winding.

8.The secondary winding is to be full wave rectified and smoothed as shown in the below diagram.

9.The DC voltage so provided will be followed by a switch mode power supply which will provide a constant power load.

(i.e. the current drawn by the load will increase as the DC output voltage falls- hence the capacitor ripple voltage will be higher at low input voltage)

10.The power drawn by the load has a maximum continuous rating (Po) of 22W.

11.Transformer input voltage range as follows:

115V (85V to 132.5V) windings in parallel

230V (170V to 265V) windings in series

Note. Extended input voltage range 85V to 265V

12.	At minimum input voltage (170V AC) the minimum voltage on the capacitor must be > 22.5V with Po = 22W
13.	At maximum input voltage and minimum load of 6W the max voltage on output capacitor must be < 63V.
14.	The secondary voltages and r.m.s currents have been calculated and are tabulated against input voltage.
The model assumes the transformer regulation is made as poor as possible while meeting spec.
The equivalent series resistance of the windings transformed to the secondary is 7ohms under this condition.
Rms figures for voltages and currents are true rms figures measured with the specified bridge rectifier, Capacitor
and load resistor connected to the transformer secondary.
In the case of the load regulation for lowest cost transformer being better than the worst case specification then the

TOP VIEW

Secondary Winding Voltage and Current Specs assuming C=1360uF, f= 50Hz for Po = 22W Bridge Rectifier Vf diode = 1.1V per leg = 2.2V Total

Ideal TX assumed with 7Ohm series resistor in secondary to simulate regulation.

AC Supply	Loaded	Capacitor	Capacitor	Capacitor	Load Resistor	Secondary
Voltage	Secondary	Peak Voltage	Min Voltage	Average	to simulate	Winding r.m.s.
Pri in Series	Voltage	Vpk	Vmin	Voltage	Load RL	Current
(V r.m.s.)	(V r.m.s.)	(Volt)	(Volt)	(Volt)	(Ohm)	(A r.m.s.)
170	23.2	26.9	23.7	25.3	28	1.3
230	37.3	46.0	43.7	44.8	88	0.86
265	44.4	55.7	53.8	54.8	130	0.75

330MM

SECONDARY

PRIMARIES

SCREEN WIRE

GREEN/YELLOW

TX1

Small Toroidal Mains

L924TX

GREY	1
	115V	5	RED
WHITE	2
PRIMARY BLACK	3	37.3V	SECONDARY
		6	RED
	115V
BLUE	4
		7

SCREEN WIRE GREEN/YELLOW

transformer voltages shall be modified so that the minimum 22.5V spec is met at 170V input and the output
voltages at 230V and 265V input voltage are lower than the specified voltages.
15.	Temperature rise to be such that transformer is safe when operated in an enclosure with 50C maximum internal
temperature.
16.	Toroid to be fitted with interwinding screen.

Mechanical Specification

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17.Primary wires self-ended and individually sleeved for colour coding, then sleeved together.

18.Secondary wires self-ended and individually sleeved, then sleeved together.

19.Wire type used on the terminations must be such that the wire may be bent with a miniumum bend radius of 10mm through an angle of 90degrees 10times without the wire fracturing. This will allow the wires to be dressed in production without risk of damage to terminations.

20.All wire lengths are +20, -0 mm. All wires stripped 8 +/-2mm and tinned.

21.Transformer to be marked with part number and issue number.

22.Toroidal transformer will be attached to the chassis by a dished washer and bolt (no potting required).

23.A frame transfomer meeting the above spec will be chassis mounted with flying leads and should have clamp fitted to allow it to be screwed to chassis.

24.Toroidal transformer to be supplied with mounting kit consisting of metal dished washer and 2 neoprene or similar washers.

Voltage on Reservoir Capacitor

	Vpk
	Vaverage
	Vmin		80mm dia max
10mS
TEST CIRCUIT		40mm max				LEADS EXIT NEAR TOP
Vf = 1.1V	+VOUT
per diode
AC IN
+ 1360uF	RL see above table.
63V
	GND
DRAWING TITLE
DV78 TRANSFORMER 115/230V			KAL	02-07-2003	Production Release		1.0
		03_E195
ARCAM	Filename: L924TX_1.0.sch	03_E086	KAL	21-03-2003	Corrected Wire Colours added notes re Clamp		B.0
	Notes:	03_E042	KAL	4-02-2003	Reduced Power Output Spec, Reduced Load Regulation Spec		A.1
A & R Cambridge Ltd.		02_E336	KAL	4-12-2003	Prototype Release		A.0
Pembroke Avenue		ECO No.	INITIALS	DATE	DESCRIPTION OF CHANGE		ISSUE
Waterbeach
						A3 DRAWING NO. L924TX
Cambridge CB5 9PB	Contact Engineer: Kevin Lamb	Contact Tel: (01223) 203243	Printed:	7-Jul-2003	Sheet 1 of 1