Hafler DH 200 Service Manual

Page 1

THE

Emefler

POWER AMPLIFIER '

DH-200

INSTRUCTIONS
for ASSEMBLY
and OPERATION

9292 Please refer In this serial
$3 00 number in I communications
I regarding this equipment.

THE DAVID HAFLER COMPANY
5910 Crescent Boulevard. Pennsauken. New Jersey 08109

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INTRODUCTION

The Hafier DH-ZOO 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 100 watt per
channel power rating is sufficient for driving all
loudspeakers in home applications, and its design provides
extremely low distortion of all types. A combination of high
performance, dependability and reliability, and moderate
price is in the Hafler tradition of using the latest technology
to provide outstanding value.

Combining the latest power MOSFET technology with
uniquely simple and effective circuit topology reduces distor-
tion 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 conven-
tional transistors - their tendency to self-destruct under
other than normal operating conditions. So rugged is the
DH-200 that it can deliver as much as ten ampercs 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, surpass-
ing 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 listen-
ing fatigue. The longer you listen to this phenomenal
amplifier, the more certain you will be that you could not
have made a better choice.

Though modest in cost, the DH-200 evidences the very
finest electrical and mechanical design. It avoids costly frills
and unnecessary gadgetry while providing quality sound and
reliability based on top grade components conservatively
operated.

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
efiorts to achieve exceptional reliability simultaneously with
state of the art Sonics and specifications And this circuit is
convertible (with an internal accessory bridging circuit
board) to a high power monophonic amplifier with
equivalent stability and specifications.

The fully complementary, symmetrical push-pull circuit,
which is direct coupled throughout (except at the input), in-
corporates all silicon devices in a format which is directly
related to the highly acclaimed DH-lOl preamplifier. Its
unique self-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-ZOO to avoid the need for special protec-
tive 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-200 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 possi-
ble to operate on one channel if the other requires service,
and obviates the need to return the entire amplifier in cases
where one channel is inoperative.

Accessories for special applications include the input
bridging circuit board for monophonic use; a panel for stan-
dard l9 rack mounting; and an alternative power
transformer for international AC line voltages.

Through advanced engineering geared to the audio per-
fectionist, and an efiicient no-frills approach. Hafler is mak-
ing high technology high fidelity affordable.

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

© Copyright 1980. All rights reserved.

Page 11

vanced design of this circuit means that some components
will not likely be available locally, and alternative replace-
ments are not recommended at all.

We recommend that a defective output module be sepa-
rated from the amplifier, and returned for service at the fac-
tory. This reduces shipping weight and the likelihood of
damage, and enables you to operate the other half if you
wish. In this case, we suggest that the connecting wires be un-
soldered at the eyelets; that each wire be tagged with the
eyelet number (visible inside the board, along the edge - or
see the board diagram in this manual); that the bare wire
ends all be insulated; the dual power supply fuses for that
channel be removed; and the wires to that thermal breaker
on the heat sink fin be disconnected and temporarily
soldered together, and insulated.

SERVICE POLICY AND LIMITED WARRANTY

The DH-200 Power Amplifier has been carefully
engineered to provide many years of use without requiring
any maintenance or servicing.

Factory assembled units are subjected to several physical
and electrical tests before shipment. The output circuit board
assemblies of kit units are similarly tested prior to shipment.
In spite of all this testing, shipping damage does occur, kits
are not assembled properly or someone goofs" and service
and/or maintenance will be required. The David Hafier Co.
provides complete service facilities at the factory to make
any necessary repairs.

It is the owner's responsibility to return or ship the unit
freight prepaid to the factory service department. Units ship-
ped freight collect will not be accepted. For units to be
repaired under warranty a copy of the dated bill ofsale must
accmnpany the unit.

Shipment should be made via UNITED PARCEL SER-
VICE. Parcel Post is not a safe way to ship electronic equip-
ment. The factory will not be responsible for damage caused
by parcel post shipment and repairs will be made at the
owner's expense. When shipping your DH-ZOO be sure to in-
sure it for the full value of an assembled amplifier.

Use the original canon and packing material to ship your
amplifier. Enclose with the unit the following information:

1. Complete shipping address (Post Office Box numbers
are often not acceptable).

2. The serial number.

3. Copy of dated bill of sale if repairs are to be made under
warranty.

4. Description of the malfunction. If intermittent, please
note.

5. We also suggest further identifying the unit as yours by
putting a label on the bottom or tieing a label with your
name and address on the line cord.

All service work is guaranteed for 90 days.
Warranties apply to the original purchaser only. Warran~
ties are void if:
1. The amplifier has been either physically or electrically
abused or used for some purpose for which it was not
designed.

ll

2. The amplifier has been modified without factory
authorization.

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 writing the Technical Services
Department. 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. He 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 return to you. If you believe
the fault is the factorys warranty 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 ser-
vice fee will be refunded. Only a complete amplifier can be
completely checked and given a service warranty.

WARRANTY FOR KIT-BUILT UNITS

The parts in a DH-200 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 pan to
the factory prepaid together with the serial number and the
date of purchase, and it will be replawd at no charge.

If you cannot locate what is wrong with your DH-200,
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 de-
fective part, the unit will be repaired and returned to you
transportation prepaid, and your $40 less a charge for re-
packaging and shipping will be returned to you. If the prob-
lem is found to be an error in your assembly of the ampli«
fier, the amplifier will be put in proper working order, test-
ed 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 war-
rants 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~200 is warranted for a full year from the
purchase date including parts and labor and normal shipping
costs from the factory to the owner within the continental
US. 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.