Hafler 0915P manual Cartridge Loads, Installing

INSTALLING

CARTRIDGE LOADS

CHANGING UNE VOLTAGE RATlNG

Optional

cartridge

loading is a “fine tuning” matter. Many

cartridges

are

not

sensitive

to

loading

and

work

well without

it. Only

a cartridge’s manufacturer

can

provide recommended

loading, as

every cartridge is different. And only the user can say

for

sure

whether

or

not it

produces

meaningful

sonic

improvement.

Components suitable for cartridge loads may be obtained

from electronic parts or specialty audio

component

suppliers. Resistors should

be 1%

tolerance,

metal-film,

l/4

watt

types. Capacitors

should

be

axial

lead,

10%

(or

better) tolerance, miniature

polypropylene

or

polystyrene

types.

As

supplied

from

the factory,

the

915

Preamplifier

has been

fitted

with 100 ohm resistors and 220

pF capacitors installed in the appropriate sockets. While		these values are suitable for most
cartridges, the procedure described below may be used		to alter these values. Review the
installation instructions before attempting this procedure.	If	any doubts	exist about	one’s ability
to install the cartridge loads, it is advisable that the	procedure be		conducted by	a qualified
technician.

WARNING! UNPLUG THE UNIT FROM AC POWER BEFORE ATTEMPTING THIS PROCE- DURE. FAILURE TO DO SO CAN RESULT IN SEVERE ELECTRICAL SHOCK AS WELL AS DAMAGE TO THE PREAMPLIFIER AND/OR PHONO BOARD.

1)

Place

the preamplifier

on

a soft, protective

surface.

Remove

the

four allen

head

screws (two

on

each

side), and

three

phillips

head

screws,

securing

the

bottom cover.

Remove cover.

2 )

Refer

to

the diagram

“Installation

Of Optional Cartridge Loads” for the

location

of

the

appropriate sockets, and how to

form the component leads. Make sure

that

the

component

leads are only long enough to securely mate to the sockets. Be sure not to stress the

component lead where

it

enters

the body of the part. Observe carefully which sockets are

for

MM

(capacitors)

and

for MC

(resistors).

3) Replace cover.

NOTE: Even while experimenting with different optional loads, the cover must be replaced before re-applying AC power, not only for safety reasons, but to shield hum and interference which can totally invalidate any attempts at sonic evaluation.

CAUTION: When low value resistors are installed and selected by the MC switch position,

accidentally using this setup for a high output moving

coil

cartridge

can

result in deceptively normal

output levels,

but

with

improper

cartridge frequency

response.

The 915

Preamplifier can

be internally wired for two different AC line

voltage ranges: 100 - 120

VAC, or 200 - 240 VAC,

50/60 Hz. The

configuration is

labelled

above

the power

cord

connector.

If the preamplifier will be

used in a location that requires a different line voltage, it

is

possible to

change

the

configuration.

Review

the

modification

instructions

before

attempting

this

procedure.

If any doubts exist about

one’s ability to change the

line

voltage,

it

is

advisable that the

procedure

be conducted by a qualified technician.

NOTE: As supplied

from

the factory, units wired for

100-l

20 VAC

have five Convenience

Outlets,

and the Power Switch controls the Switched Convenience Outlets only. (Power is applied to the preamplifier’s circuitry as soon as the unit is plugged in.) For units factory wired for 200-240 VAC,

no Convenience Outlets are supplied, and the Power Switch controls application of power to the

preamplifier’s	circuitry. Note that changing the Line Voltage affects only the operating line voltage:
the above	described switching arrangements will remain the same.

WARNING! UNPLUG THE UNIT FROM AC POWER BEFORE ATTEMPTING THIS PROCE- DURE. FAILURE TO DO SO CAN RESULT IN SEVERE ELECTRICAL SHOCK.

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