POWER AMPLIFIER
INSTRUCTIONS for OPERATION and KIT ASSEMBLY
CAUTION: IF THE SPEAKER FUSES BLOW, SOME DISTORTED SOUND CAN BE HEARD. THEREFORE IF AMPLIFIER MALFUNCTIONS, ALWAYS CHECK FOR BLOWN FUSES FIRST.
THE DAVID HAFLER COMPANY 5910 Crescent Boulevard, Pennsauken, New Jersey 08109
Hafler DH-200 Power Amplifier

serial

number in all communications

INTRODUCTION

The Hafler DH-220 is a two channel audio power amplifier designed to the very highest performance standards. It is available either as a kit, or fully assembled. Its 115 watt per channel power rating is sufficient for driving all loudspeakers in home applications, and its design assures extremely low distortion of all types. A combination of high performance, dependability, reliability, and moderate price is in the Hafler tradition of using the very latest technology to provide outstanding value. The DH-220 circuit is a refinement of the DH-200 design, a Hafler landmark which has achieved worldwide recognition, and has elicited glowing reviews since its 1979 introduction. As in the DH-110 preamplifier, particular attention has been paid to component quality, using polypropylene or film capacitors wherever feasible, for example, for superior sound. Combining the latest power MOSFET technology with uniquely simple and effective circuit topology reduces distortion of all types, and at all power levels, over the full audio frequency spectrum, to the vanishing point. In addition to its pace-setting performance achievements, the conservative mode of operation accomplishes a new high in long term reliability and exceptional resistance to abusive operating conditions. This is one of the direct benefits of MOSFET utilization in overcoming a serious limitation of conventional transistors - their tendency to self-destruct under other than normal operating conditions. So rugged is the DH-220 that it can deliver more than ten amperes into a short circuit! The speed - measured as the slew rate - of this design delivers unmatched transient linearity, revealing the most delicate shadings, textures and nuances of the music, surpassing the capabilities of the most revealing loudspeakers and cartridges by a wide margin. Coupled with its unconditional stability, and ability to deliver adequate power into any loudspeaker load, the result is absolute freedom from listening fatigue. The longer you listen to this phenomenal amplifier, the more certain you will be that you could not have made a better choice. The oversized power transformer and bridge rectifier; the massive heat sinks; the conservative operating levels of the MOSFET output devices - all are evidence of the design efforts to achieve exceptional reliability simultaneously with state of the art sonics and specifications. And this circuit is convertible to a high power monophonic amplifier with comparable stability and specifications. The fully complementary, symmetrical push-pull circuit, which is direct coupled throughout (except at the input), incorporates all silicon devices in a format which is directly related to the highly acclaimed DH-110 preamplifier. Its unique selfDH-110 protecting output stage prevents the thermal runaway which is a common threat to solid state amplifiers. The ruggedness and conservative operation of the output stage allows the DH-220 to avoid the need for special protective circuits which could compromise audio performance. Basic protective systems provide maximum security against malfunction damage to the amplifier or the speaker: the AC line fuse, B + fuses, thermal breakers, and loudspeaker fuses. Nothing hinders the essential purity of the audio signal. Those who use these instructions to assemble the DH-220 kit will find that the left and right audio modules (printed circuit and heat sink assemblies) are preassembled and pretested. This greatly simplifies the kit assembly so that it can be done in only a few hours without special skills or know-how. Because of the modular arrangement, it is possible to operate on one channel if the other requires service, and avoids the need to return the entire amplifier in cases where only one channel is at fault. Accessories for special applications include provision for monophonic use; a panel for standard 19 rack mounting; and an alternative power transformer for international AC line voltages. Through advanced engineering geared to the audio perfectionist, and an efficient no-frills approach, Hafler is making high technology high fidelity affordable.

CONTENTS

Operation. Page 3 Assembly Instructions. 4 Wiring the Kit.. 6 If Problems Arise. 10 Service and Warranty. 11 AC Line Connections for Overseas Use. 12 Kit Parts List.. 13 Schematic Diagram. Component Value Listing. 15 Pictorial Diagram. Insert

A soldering gun is not recommended. The unfamiliar user is more likely to damage the etched circuit boards with its higher heat potential and unbalanced weight. Also, because he may not wait long enough for it to reach operating temperature each time it is switched on, poor solder connections are more likely. Pencil irons are much lighter and easier to use, and there is no waiting time when solder connections follow in sequence, as in kit building. Make sure you have a holder for it, though, and always unplug it when you take a break.
few seconds to allow a good bond. When cool, check the connection by wiggling the wire. If in doubt, or if the connection is not shiny, re-heat the joint. Excess solder may be removed from a connection by heating it and allowing the solder to flow onto the iron, which is then wiped on the sponge. ALL SOLDER USED MUST BE ROSIN CORE. Never use acid core solder or any separate flux in electronic work. Silver solder is also not suitable. If in doubt about unmarked solder, always obtain a fresh supply of rosin core solder. We recommend 60/40 for easiest use. Do not confuse it with 40/60, which is harder to melt. The general procedure is to use a hot iron for a short time to heat a connection, then add solder with the iron still in contact. Remove the solder once it flows, and then remove the iron. A cooler iron applied for a longer time is more likely to damage components, or lift the copper circuit pattern from the boards. A break in the etched circuit can be mended by simply soldering a small piece of wire across it. Do not allow much build-up of solder on the tip of the iron, or it may fall into adjacent circuitry. When soldering to a numbered hole on the board, insert the wire from the components side, and apply the iron, leaving some bare wire exposed so that you can see that the hole is then filled with solder for a secure bond. A round wooden toothpick is suggested so that you can heat and clear the hole of solder if it hinders your inserting the wire. Some builders prefer to clear every hole first with a touch of the iron and toothpick. If the wire has first been tinned, no additional solder may be necessary if solder fills the hole, but it is good practice to push the wire through, and then back it up a bit, to be sure solder fills the hole from both sides. Make certain a bright, shiny flow is evident from the wire, across the hole, onto the circuit pattern on the board. Tinning refers to the process of applying a light coating of solder to the bared wire end. This keeps all the strands secured, and also makes a good connection easier. Simply touch the wire with the iron for a couple of seconds, and apply solder. Allow the excess to flow away onto the iron. When properly done, the wire is uniformly bright, and no larger than before. The hookup wire supplied with this kit does not normally need tinning, for it is pre-tinned.

Proper Soldering

There are four steps to making a good solder connection: Make a good mechanical connection to hold the wire in position while heat and solder is applied. Heat thejunction of the wire and lug, or hole, with the bright, shiny top of the iron. After heating for a couple seconds, apply solder to the junction. It should melt immediately and flow smoothly around both surfaces. Allow the connection to cool undisturbed. Remember that the connection is made by the solder, not by mechanically attaching the wire to the terminal. Usually the wire is looped through the lug and crimped in place, but some prefer to just place it through the hole and rely on the stiffness of the wire to hold it while soldering. Connections to numbered holes on the circuit board are handled this way. Good solder connections are essential for trouble-free noisefree operation. A good solder joint does not require much solder around the conductors. Never butter partially melted solder on the joint, as it is useless. A good connection looks smooth and bright because the solder flows into every crevice when the parts are hot enough. The iron must have a bright, shiny tip to transfer heat easily to the junction. That why the damp sponge s should be used frequently to wipe the tip, and occasionally you must add a small amount of solder to the tip, too. If a connection is difficult to heat, wet the tip with a small blob of solder to provide a bigger contact surface to the joint. Once the solder flows around the conductors, any movement must be avoided for a

Wiring the Kit

If any components are unfamiliar to you, checking the pictorial diagram should quickly identify them. Or, the quantities, and the process of elimination as you check the parts list, will help. The pictorial diagram is necessarily distorted to some extent for clarity, so that you can trace every wire in a single overall view for verification as you work. You may wish to check off on the diagram as you solder each location. To prepare a wire means to cut the designated length from the coil of that color, and strip about 1/4" of insulation from each end. The wire supplied in the kit is #18, so you can set adjustable wire-strippers accordingly. The transformer leads are #16 or #18 and the line cord is #16. Be careful that you do not nick the wire when you strip it (that can happen more easily if you do not use wire strippers) for that weakens it. The wire supplied in this kit is bonded stranded, which provides exceptional flexibility with resistance to breakage for easier use, and it is pre-tinned. Whenever a connection is to be soldered, the instructions will so state, or indicate by the symbol (S). If more than one wire is to be soldered to the same terminal, they will be indicated by (S-2), (S3), etc. If soldering is not called for, other connections have yet to be made to that terminal. They would be more difficult if the connection was already soldered. Every connection in the kit will be soldered when it is complete. After soldering a connection, it is best to clip off any excess lead length to minimize the possibility of a short circuit (as on switch lugs, where terminals are very close together), and for a neat appearance. Be sure that uninsulated wires cannot touch adjacent terminals or the chassis metalwork. The symbol (#) indicates a connection is to be made to that point. When a lug number is specified without (#) it is simply a locating reference. When the instructions call for twisting two or three wires together, the length of wire indicated anticipates a fairly tight, uniform twist by hand, of three full turns every two inches. If you find the wires too short, loosening the twist will gain some needed length. Handle the circuit boards carefully. They represent a major part of the kit cost. Stand-up components, such as transistors, should be checked when you install the module, to be sure all leads are separated. All of the active circuitry is contained on the PC-19 board, which has been carefully tested to assure that it meets every specification. Only the interconnection of power supply elements is left to the builder. Take the time to be accurate and neat, and you can be sure that your completed amplifier will meet the performance of a factory assembled unit, and can continue to perform properly for years to come. Check your work, and make sure the entire step has been completed before placing a check mark in the space provided, and continuing on to the next step. KEP nuts have been supplied as a convenience. These have lockwashers attached, and the lockwasher always goes onto the screw first. If the sheet metal screws have hex heads, you may 6

NOTE: Kits provided with the multiple voltage power transformer for use in locations outside the United States having a line (mains) voltage other than 120 VAC are also supplied with an additional twolug terminal strip which is to be installed using an additional set of #4 hardware on the other side of the chassis, below the dual fuse clip FL.
Connect the shorter lead to FC lug #l. (S). Connect the longer lead to the lower hole of TS lug #2. (S). Note that lug 2 is the second protruding lug on the terminal strip. It is not the mounting bracket for the terminal strip. Soldering this lead to the lower hole now will make later connections to the top portion of the lug easier. Be sure no stray strands of either line cord conductor are left unsoldered. 14 Prepare a 6 1/2" green wire. Connect one end to dual fuse clip FL lug #l. Connect the other end to the other dual clip FR lug #l. (S). Prepare a 6 1/2" white wire, Connect one end to FR lug #3. Connect the other end to FL lug #3. (S). Prepare two 7 white wires. Start with one wire projecting 3/4" beyond the other, and twist them uniformly together throughout their length. Connect the projecting end to RF lug #l. (S). Connect the corresponding end of the other wire to RFlug #2. (S). Place this pair over the right edge of the chassis.
170 Prepare two more 7 white wires. Start as before with one wire 3/4" longer, and twist them together. Connect the longer end to LF lug #2 (S). Connect the other wire to LF lug #l. (S). Place these wires off to the left. Prepare an 8 green wire and a 10 white wire. Start with the white wire 3/4 longer than the green wire, and twist them uniformly together. Connect one end of the green wire to the lug on black output terminal LB. Connect the corresponding end of the white wire to red terminal LR. (S). Place these wires off to the left.
Select the power switch. Install it with the red window to your right as viewed from the front. The switch snaps into chassis hole PS from the outside. 13 q Select the AC line cord and the plastic strain relief. Separate the two conductors for 2. Cut 1 off one of the two leads, and strip 1/4" of insulation from each lead. Twist the strands tightly, and tin each end. Make a sharp 'V' in the cord 8 1/2" from the longest cut end by bending it back on itself. Install the relief with the small end nearest the cut end of the cord. Crimp the two halves of the relief around the wire at the 'V' with heavy pliers, to partially form it before insertion into back panel hole AC. Then grip the larger diameter with the plier tips, squeeze it tightly, and insert the cord and the relief from the outside. A flat side of the relief mates with the hole shape, and it snaps into position when fully inserted.

19 c3 Prepare a 7 green wire. Connect one end to terminal LB. (S-2). Place this wire towards the center of the chassis. 20 Ll Prepare a 10 white wire and a 10 green wire. Starting with the white wire 3/4" longer, twist them together. Connect the projecting white wire to red terminal RR. (S). Connect the green wire to terminal RB. Place these wires off to the right. C Prepare a 51/2" green wire. Connect one end to terminal RB. (S-2). Place this wire towards the center of the chassis. Prepare a 16 green wire, but strip 1 1/4" of insulation from one end. Prepare a 15 white wire. Start with the normally stripped (l/4) ends even, and twist these wires uniformly together. Thread the longer bared end of the green wire through LS short lug #2 from the top left, then through GLlug #3, and connect it to RSshort lug #4. Solder only LS lug #2. Connect the corresponding end of the white wire to LS lug #l. (S). Place this wire up under the chassis rear lip, above the output terminals, and off to the left. 23 L! Prepare a 6 1/2" green wire. Connect one end to CL lug #3. (S2). Place this wire over the rear of the chassis. 24 C Prepare a 10 green wire and a 10 white wire. Twist these together with the ends even. Connect the green wire from the right to RS short lug #4. (S-2). Connect the white wire to RS lug #5. (S). Place these wires off to the right. Prepare two 22 white wires, and twist them together throughout their length. 8 in from one end of the pair, cut one of the wires, and unwind it about 11/2" in each direction from the cut. Strip 1/4" of insulation from each of these cut ends. Place the longer portion of the wire along the lower front edge of the chassis, with the break at the terminal strip TS. Connect the cut end from the left to TS lug #2. Connect the other end to the lower hole of TS lug #5. (S). Place this pair along the front edge of the chassis, under the power switch, with the ends projecting from the front corners of the chassis. 26 il Select a 1 megohm resistor (brown-black-green) and trim the leads to 1/2. Connect one lead to TS lug #2. (S3). One of these 3 leads has already been soldered to the lower lug hole. Connect the other lead to TS lug #3. 27 n Select the diode and trim its leads to 1/2. Note that one end of the diode is marked with a stripe (or an arrow head will point to that end). Connect the marked end to TS lug #4. Connect the other lead to TS lug #3. (S2). Prepare a 4 green wire. Connect one end to TS lug #4. Select a spade connecting lug, and solder it to the other end. Place this wire down against the chassis, and connect it to the PS lug on the right, near the edge of the chassis. The proper way to attach a spade lug to a wire is to first cut the bared wire end to the right length (no more than 1/4" so that the insulation will be securely gripped by the longer, outer tabs, while the wire does not protrude into the spade clamp area. Tin the bare wire end. Bend the 8 29

shorter, middle set of tabs tightly around the bare wire, and then bend the longer tabs around the insulation. Then flow solder into the joint around the bare wire, keeping the solder away from the spade section. Prepare a 2 white wire. Connect one end to FC lug #2. (S). Select another spade lug, and solder it to the other end. Connect it to the PS middle lug.
Select the 0.39 mfd (.39K) capacitor and trim its leads to 1/2" Connect one lead to TS lug #4. (S3). Connect the other lead to TS lug #5. Select the two large round capacitor brackets, the two large capacitors, and 6 sets of #6 hardware. Place a bracket around the bottom of each capacitor, and fasten it snugly with one set of hardware through the clamp. Note the direction of insertion of the screw for easy servicing access in the future. The clamps need not be tightened now - just made snug. Place each assembly on the chassis, at CL and CR, noting the position of the clamp, and fasten them securely. Be sure no wires are trapped by the bracket. Then loosen the clamps, and position the capacitors so that each + terminal is positioned as in the pictorial diagram. The + terminal will usually be so marked, but if not, it may be identified by a red dot. Note that the + terminal of CL is nearest the terminal of CR. Make sure the capacitors are seated against the chassis and tighten both clamps. Select the 4 plain solder lugs and then 4 short #lO SEMS screws (with lockwasher attached). Install these in the capacitors, with the lugs pointing as in the diagram. 33 C Prepare a 6 green wire. Connect one end to DB lug #l. (S). Connect the other end to CL lug #l. 34 E Prepare a 4% green wire. Connect one end to FL lug #l. (S-2). Connect the other end to CL lug #l. (S2). 35 G Prepare a 6 white wire. Connect one end to DB lug #4. (S). Be sure this is the + terminal of the rectifier. Connect the other end to CR lug #2. 36 q Prepare a 4 3/4" white wire. Connect one end to FRlug #3. (S-2). Connect the other end to CR lug #2. (S2).
Remove all insulation from a 3 white wire. Connect one end to CL lug #2. (S). Connect the other end to CR lug #l. (S). 38 [7 Select the power transformer, the 4 flat washers, and the 4 sets of #10 hardware. Position the transformer with the red leads to the center rear of the chassis, and the black and black/white leads towards the power switch. If the transformer is the special multiple voltage version, the additional leads should be placed as shown elsewhere in this manual for the desired line (mains) voltage. The red/yellow lead will likely be the correct length. If you wish to shorten the red leads for neatness in connecting them to the rectifier terminals, it is easier to strip them before the transformer is mounted. Place the white pair of wires under the front chassis lip. Install a flat washer on top of each transformer foot after the screw is inserted from below, and then add the nut. Be sure no wires are trapped.

The transformer leads may be trimmed as desired for a neat job, but be sure you do not cut any of them too short (particularly if yours is the multi-voltage version, and any change to a different supply voltage is likely). Cutting the leads too short for re-use may void its warranty, if it is thought to be defective. Consult the multi-voltage diagrams elsewhere in this manual fcr connections to the terminal strips which may differ from the stepbystep instructions here. Be sure all strands of each transformer lead are tinned and soldered together before connection to a lug, so that there is no possibility of a stray strand touching anything but the lug. Select the remaining spade lug, and solder it to the black transformer lead. Connect it to the PS left lug. u Select the.005 (502M) disc capacitor, and trim its leads to l/2 or less. Wrap one lead around the shaft of the spade lug which is connected to the PS left (inside) lug. Wrap the other lead around the shaft of the spade lug connected to the middle lug. Solder both leads. Be sure there is adequate clearance between these connections, and that the spade lugs are fully engaged. 41 Connect the black/white transformer lead to TS lug #5. (S3). One of these wires was previously soldered to the lower hole of this lug.
these. If it is filled with solder, running the iron along the underside will uncover the hole, and it may be cleared with a wooden toothpick. Now position the right module (with the breaker at the front when the long bottom row of eyelets is next to the chassis) with the circuit board up, against the side of the chassis. Wires will be connected to the holes from the top of the board, and you must be sure they are soldered securely to the bright circuit pads Each hole is . plated through - it makes a connection to the other side of the board - and a good solder connection which heats the wire and the circuit pad properly will allow solder to flow through the hole for a secure connection. Even though the connecting wires are just long enough to make the connections now, they will be rather long when the amplifier is completed. That is why working room is limited. Any wire which is to be connected to a hole on the board should have a tight, tinned end. The wire supplied in the kit is already tinned, so it would not normally require additional tinning unless the tip is frayed. Melt a small amount of solder on the tip of the iron so that it will make a good contact with both the bared wire end, and the circuit pad as the wire is inserted into the hole. Then add additional solder so that there is a smooth, bright transition from the wire to the board as it cools undisturbed. If you must use a great deal of heat on a connection, make sure that you have not loosened any adjacent connections in the process - especially wires from the back side of the board. The holes #lo and #3 are very close to capacitors on the board. Be sure heat does not damage these capacitors.

55 I Select the white pair of wires at the front of the chassis. Tuck the excess-wire into the corner and connect one wire to each of the lugs on the thermal breaker. Solder each. [ Select the left output module, check it as before to see that underside connections near the holes are secure, and that the holes are visible. Place it against the left side of the chassis with the breaker at the front, board up. Prepare a 6 green wire. Connect one end to hole #lo. (S). Be sure it cannot touch the transistor mounting screw! Connect the other end to FL lug #2. (S). Select the green and white pair from output terminals LB and LR. Connect the green wire to hole #7. (S). Connect the white wire to hole #5. (S).
green ground leads from the black output terminals and the ground lug should be brought together through most of their length. Check all your soldered connections - especially those on the fuse clip lugs, which are sometines difficult to solder to. Clip off any excess bare wire which could short to adjacent lugs or the chassis. Pay particular attention to the stranded wires from the transformer and line cord, and check the power switch connections. Now turn the amplifier upside down and shake out any bits of wire or solder. Slide the cover in place, and install it with the eight sheet metal screws.
59 I Select the white pair from LF. Connect the shorter wire to hole #8 (S). connect the other wire to hole #6 (S). 60 : Prepare a 5 1/2 white wire. Connect one end to hole 3. (S). Connect the other end to FL lug #4. (S). Select 4 sheet metal screws and fasten the module to the chassis, making sure no wires are trapped.
Remove the backing from the serial number label, and apply it to the bottom at the center rear. (This may have already been done at the factory.)

IF PROBLEMS ARISE

Each circuit module, which comprises all the active amplifier circuitry, has been incircuit tested to standards identical to factory built amplifiers, prior to being packed in a kit. Thus, with careful assembly, the likelihood of a circuit fault is near zero. If you are certain the problem lies in the power amplifier, check the pilot lamp. If it is blinking, excessive temperature has shut down the amplifier. After a few minutes to cool, it will turn on automatically. If it soon shuts down again, and the amplifier has sufficient ventilation, the malfunction is either internal, or the result of an excessive (and very likely inaudible) input signal. In that case, the source must be investigated. If the pilot lamp is not lighted, the main fuse in the single fuse clip near the power switch is probably open. If a replacement 7 ampere Slo-Blo fuse (do not use a larger value) also blows, the amplifier has a power supply problem, and requires professional service. If there is a problem in only one channel of the amplifier, that channel may be isolated by removing the power supply fuses in the adjacent dual fuse clip, and the other channel may be used monophonically. We do not encourage local service of this amplifier because some components may not be available locally, and substitutions are not recommended at all. You may return a defective module for factory service. This reduces shipping weight and the likelihood of damage. To remove the module (leave the heat sink attached to the circuit board) tag each wire with the circuit board hole number as you unsolder it from the board, and insulate each bare wire end. It is safer to also remove the power supply fuses from that channel. The wires to the thermal breaker must be temporarily soldered together, and insulated.

The transformer warranty is void if the leads have been cut too short for reuse. If you think a transformer is defective the leads must be unsoldered, not cut, for its return. Technical assistance to help you locate the source of a problem may be obtained by calling the Technical Services Department at 609-662-6084, 8 a.m.-4:30 p.m. E.T. It is helpful to know the serial number of the unit and the results of any tests you have performed. SERVICING AN AMPLIFIER MODULE If you are certain that the problem is confined to one of the amplifier modules (comprising the circuit board, heat sink, and output transistors), you may remove and return only the module for service. Be sure that the components on the circuit board are well protected - as by a surrounding sleeve of corrugated cardboard which rests against the heat sink, and projects beyond the components. Properly packed and insured for $150, this assembly can be sent by parcel post, as well as UPS, if necessary. A service fee of $20 must be sent with every module, since the fault may have been caused by a wiring error elsewhere. For this reason, too, and because we have no control over its proper reinstallation, the service warranty on a separate module is limited to assurance of its proper functioning when it leaves the service facility. All modules are tested before being returned to you. If you believe the fault is the factory warranty s responsibility, include the serial number and the bill of sale. If in our judgement the fault is entirely a manufacturing defect, a portion of the service fee will be refunded. Only a complete amplifier can be fully checked and given a service warranty. WARRANTY FOR KIT-BUILT UNITS The parts in a DH-220 kit are warranted for a full year from the purchase date. If a defective component is found on a circuit board or in a kit, simply return the individual part to the factory prepaid together with the serial number and the date of purchase, and it will be replaced at no charge. If you cannot locate what is wrong with your DH-220, return it to the factory with a copy of the dated bill of sale, and a check for $40. If the sole cause of the problem is a defective part, the unit will be repaired and returned to you transportation prepaid, and your $40 less a charge for repackaging and shipping will be returned to you. If the problem is found to be an error in your assembly of the amplifier, the amplifier will be put in proper working order, tested to be sure it is meeting specifications, and returned to you (freight prepaid within the continental U.S.). Excess shipping charges for expedited service, or overseas delivery are your responsibility. At the sole discretion of the factory service department, if the time required for diagnosis, repair and testing, and the nature of the malfunction warrants it, a portion of the submitted repair fee may be rebated. This warranty is void if the kit has not been completely assembled or if other than rosin core solder has been used. Units assembled with acid core solder or paste flux will be returned unserviced. WARRANTY FOR FACTORY ASSEMBLED UNITS The DH-220 is warranted for three years from the purchase date including parts and labor and normal shipping costs from the factory to the owner within the continental U.S. The owner is responsible for returning the unit to the factory and must submit a copy of the dated bill of sale. This warranty gives you specific legal rights. You may also have other rights which vary from state to state. 11

-0.32 0.8 0.8

0.22 0.22 0.22

Q4 Q5 Q6

QlO Q11

Ql2 Q13

Q401 Q402 Q403 Q404
KIT PARTS LIST KIT PARTS LIST
Minor variations may sometimes be encountered in value or appearance. These will not affect performance.
Fuse Envelope 6 Fuse, 5 ampere 2 Fuse, 2 ampere 1 Fuse, 7 ampere, Slo-Blo 1 Additional fuse, 4 ampere, Slo-Blo (International use only) Hardware Envelope 1 Lug, solder type, internal tooth, #Lug, solder type, #lO 3 Lug, spade, l/Nut, #4-40 KEP 11 Nut, #6-32 KEP 4 Nut, #l0-32 KEP 2 Nut, l/2, for fuse holder 12 Screw, machine, #4 x 5/ Screw, machine, #6 x l/Screw, machine, #l0 x l/Screw, #l0 x l/4, SEMS 16 Screw, sheet metal, #6 x l/Screw, machine, #6 x 3/Washer, flat, 7/Washer, locking, internal tooth, l/2 for fuse holder 2 Washer, rubber, l/2, for fuse holder Small Parts Envelope 1 Capacitor,.0l mfd, disc (103M) 1 Capacitor,.005 mfd, disc (502M) 1 Capacitor,.39 mfd 1 Diode 1 Label, serial number 1 Resistor, 1 megohm
Part No. SF012 SFSFSF026 Part No. HZHZxzo14 HKlll HK112 HK113 HK118 HAHAHAHAHPHAHW114 HW116 HRll7 Part No. CZ112 CZ113 CEl l7 QD115 LR015 RDl13
Part No. 1 Chassis MS149 Cover MS152 CL121 Capacitor. 10,000 mfd, 75V Bracket, round, for capacitor HZ125 Diode rectifier block QDll1 Feet, rubber HR149 Fuse holder, round XA013 Fuse clip, single XA012 Fuse clip, dual XA014 Input socket XPO14 Line cord, with plug WA016 Output module assembly (1 each, left & right) AH326 Output terminal, black, with hardware XKOll Output terminal, red, with hardware XK012 Power switch SLlll Strain relief, plastic HR144 Terminal strip, 5 lug XK018 Additional 2 lug terminal strip (International use only) XK016 Power transformer TA123 Alternate transformer (International use only) TA124 Wire, white, #18 WS024 wso22 Wire, green, #18 LM016 Registration card

- - o , * +d2-D3+t -Rg-

-R4_R 2-C2__cs-
VIEWED FROM COMPONENT SIDE
COMPONENT VALUES COMPONENT VALUES
All resistors are l/4 w carbon film unless specified otherwise
Rl R2 R3 R4 R5 R6 R7 R8 R9 RIO Rll R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 R30 R31 R32 R33 R34 R35 R36 R37 R38 RR402 R403 R404 R405 Cl C2 C3 C4 C5 C6 C7 C8 C9 Cl0 Cl1 Cl2 Cl3 Cl4 Cl5 Cl6 Cl7 Cl8 Cl9 C20
470,000 ohms 1,800 ohms 47,000 ohms 47,000 ohms 1,000 ohms 1,000 ohms 47,000 ohms 560 ohms 560 ohms 1,800 ohms 1,800 ohms 270 ohms 47 ohms 47 ohms 47 ohms 47 ohms 1,800 ohms 1,800 ohms 270 ohms 1,800 ohms 82 ohms 560 ohms 470 ohms 10 ohms 33,000 ohms 3,300 ohms, lW, metal film 1,000 ohms, 1/4W, metal film 150 ohms, 1/4W, metal film 1,800 ohms 82 ohms 47 ohms, 1/4W, carbon comp. 47 ohms, 1/4W, carbon camp. 220 ohms, 1/2W 2,200 ohms, 1/2W 10 ohms 1 ohm, 1OW 10 ohms, 5W 28,000 ohms, 1/4W, metal film 470 ohms, 1/2W 470 ohms, 1/2W 220 ohms, 1/2W 220 ohms, 1/2W 1 meg ohms, 1/2W 2 mfd, 5OV, Film 330 pF, 63OV, Film.Ol mfd, 25OV, Film.OOl mfd, 25OV, Film.OOl mfd, 25OV, Film 0.1 mfd, lOOV, Film 0.1 mfd, lOOV, Film 470 mfd, 1 OV, Non-polar Electrolytic 150 pF, 63OV, Film 330 pF, 63OV, Film.Ol mfd, 25OV, Film 100 mfd, lOOV, Electrolytic.Ol mfd, 25OV, Film 100 mfd, lOOV, Electrolytic.Ol mfd, 25OV, Film.Ol mfd, 25OV, Film 150 pF, 63OV, Film.Ol mfd, 25OV, Film.Ol mfd, 25OV, Film 0.1 mfd, lOOV, Film

IM Distortion ( S M P T E:) Less than O.OOS%, from 1 watt to 1 15

watts into 8 ohms.

Typical THD at 115 watts into 8 ohms:
60 to 10 kHz into 8 ohms z
Rise Time: 10 kHz. 60 volts peak to peak square wave, %
I kHz - 0 0025% __ IO kHz - 0. 7 % 20 kHz - 0.012/
Frequency Response into 8 ohms:

to % 2.5 us.

Slew Rate: 10 kHz. 60 volts peak to peak square wave: 30 VI,~ s. Semiconductor Complement: 26 transistors. 8 power Mosfets, 29 diodes, 4 zener diodes. 1 diode bridge.
- 3 dB. 2 Hz to 160 kHz at 1 watt +O, -0.5 dB, 6 Hz to 60 kHz at watts
Typical Channel Separation: 20 Hz:> 75 dB
Power Consumption: watts into 8 ohms: 840 VA;
1 kHz:>85 dB 20 kHz: >6S dB
Signal to Noise Ratio, unweighted: Better than 100 dB at 115
Quiescent: 125 VA. Size: 5-1/8 high. 16 wide, 10-l/2 deep.

Net Weight: 26 Ibs.

Shipping Weight: 30 Ibs.
All Specifications are subject to change without notice.

Printed in USA

INSTRUCTIONS FOR THE HAFLER DH-222 AMPLIFIER BRIDGING KIT DH-222 FOR THE DH-220
The DH-222 may be installed in a Hafler DH-220 power amplifier to enable easy conversion to a high power monophonic amplifier, bridging the two conventional channels to a single floating output which can deliver in excess of 400 watts into an 8 ohm load. Its rated power output is 350 watts across the audio band. When switched to monophonic operation (UP), signal input should be provided to the LEFT input jack only, and the output should be connected only to the two center BED ( +) terminals. No connection of the load is to be made to the black output terminals. Because of the floating output, neither side of the load may be grounded. Thus it is unlikely that stereo speaker switching boxes, or headphone adapters may be used, as these often have a common ground between the left and right channels. The speaker fuses may be replaced with higher values than the 2-5 ampere range suggested for stereo operation, if desired, depending on the degree of protection for the speaker which is intended. The graph shows the nominal sustained power output limit of a 7 ampere standard fuse, which is the maximum recommended value. Smaller values will provide more protection for the speakers; larger ratings are at the user risk. s Both speaker fuses should be the same value. If one speaker fuse blows in mono operation, both should be replaced, for it is likely that the second has been weakened. For equivalent load impedance, each speaker fuse provides the same power output protection as in stereo operation. With the internal conversion switch DOWN, the amplifier functions as a conventional stereo amplifier, with normal input and output connections. The minimum recommended load impedance, which is limited only by thermal factors (ability of the heat sinks to dissipate high energy levels), is 6 ohms in mono; the usual 3 ohms in stereo. The amplifier circuit can safely accommodate lower impedance loads, of course. The conversion, which takes less than an hour, involves only changes to the input wiring, and installation of the switch with its mounting bracket and one resistor. These instructions assume familiarity with the usual kit building descriptions, and reminders. For more details in this regard, see the construction section of your DH-220 amplifier manual. You must be certain you have made a good solder connection wherever one is called for, not only to the wire you have attached, but to any others already connected to that point. The notation ( S) indicates a soldered connection; (S-2) denotes that there are two wires to be soldered. Use only 60/40 rosin core solder. Be careful not to let the soldering iron touch adjacent components on the circuit board: excessive heat could change their operation, with the possibility of damage to the amplifier.

12 cl Select the red and black pair from the right channel circuit
board holes 1 and 2. Connect the black wire to switch lug #3. (S-2). Connect the red wire to lug #2. (S). 13 Cl Select the green and black pair and separate the wires for about 1%. Connect the green wire to right circuit board hole A. (S). Connect the black wire to hole E. (S). Hole A is located in line with the switch about 11/2 from the rear edge of the board. E is located 1/2 below hole 2, near the top of the board. I4 Cl Place the green and black pair towards the rear of the module, and down past the midline of the switch. Where it passes lug #5, approximately 41/2"from the end of the wires, cut only the green wire. Strip each end 1/4" Connect the short green section to switch lug #4. (S-2): Connect the longer green wire from the left board to switch lug #6. (S). Be careful no wires are pinched as you reinstall the right modI5 ule to the chassis with 4 screws. Place the long green and black pair under the rear lip of the chassis. The pairs to the top eyelets on each board, and to the connections in the center of the board should be kept at least 1/2" off the board, where they are clear of the components. Make sure the unconnected black wire end near the left circuit board cannot touch any components. The switch lever should be placed in the upper position for 16 monophonic operation. In the lower switch position, the amplifier functions as a conventional stereo amplifier. Reinstall the amplifier cover with the remaining 8 screws.