Hafler 0915P manual screws

GENERAL TROUBLESHOOTING HINTS

Place the preamplifier on a	soft, protective	surface. Remove the eight allen	head	screws	(four
on each side), and six phillips	head screws	(three each on top and bottom),	securing	the top	and
bottom covers. Remove covers.

2)Referring to the diagram “Main Printed Circuit Board Component Layout”, locate the three wire

jumper

locations labelled “A”,

“B”, and

"C",

in

front of the power transformer. These jumpers

control

the

series/parallel

connections

of

the

power

transformer’s

primary.

3 )

Remove

the

old

jumper(s)

by

desoldering

and

replace

with new

jumper(s) as indicated:

100

-

120 VAC: Jumpers A & B installed

200

-

240

VAC:

Jumper

C installed

Be sure to clip off excess wire length on the solder (non-component) side of the printed circuit board.

4)Referring again to the diagram, locate the clip-mounted fuse. Replace this fuse with a new slow- blow fuse as indicated:

100 - 120 VAC: 1/10 AMP

200 - 240 VAC: 1 /16 AMP

5 )	Referring again		to the	diagram, locate	the wire	jumper location labelled	“Remove	For 240
	VAC”,	behind	the transformer. This jumper controls the voltage supplied				to the	Power Switch
	indicator	lamp.	Remove	or install this	jumper	as indicated:

100 - 120 VAC: Jumper Installed

200 - 240 VAC: Jumper Removed

6) Replace the covers.

7)Obtain a new voltage configuration label from the factory, and affix over the original markings. Alternately, prepare a small self adhesive label and indicate the new voltage range with

permanent

ink.

Relabelling

the

unit is

a

vital

safety

requirement,

particularly

if

the

preamplifier

is sold to a new owner.

The 915 Preamplifier is configured

for normal operation when all toggle

switches

are

in

the

“down”

position.

That

is,

Tape

Monitor

is NOT selected,

Tone

Controls are

OFF,

and

the

outputs are

ON. If

no

sound

is

heard

from the system,

first check the position of the Tape

Monitor

and

Output

switches.

If altered tonal balance is detected

(even

with

the

Bass

and

Treble

controls

centered),

check

the

position

of

the

Tone switch.

If

the

Ready

light is

off

or

glowing red, the

preamplifier’s outputs are

muted

and no

sound

will

be

heard.

If rated AC power is present and the light is glowing red, then the delay

circuit will un-mute the

outputs

within

several

seconds.

If the delay circuit

does not un-mute

within

a

few seconds

and

the

light

continues to glow red, check for low AC line voltage, and that the unit

is configured

for the

local

line

voltage.

If

the

Ready

light is

off,

check the AC power connections.

If

all

controls are

in

the

intended

position

and

the

Ready

light

is green,

check

all

system

power

connections, interconnecting and speaker cables, and fuses. The 915 does contain one internal

power fuse,	but	this fuse should not generally blow	unless	a malfunction has occurred. This fuse
should be replaced only with the exact type and rating			of fuse	originally supplied. If this fuse is replaced
and blows	again	within a short time, disconnect all	power	immediately and return for service.

If all controls, fuses, cables, etc. seem to be functioning properly, a process of one-at-a-time

component substitution		should be employed until the	defective unit	is	identified.	If only	one	channel
is not	functioning properly, a one-at-a-time reversal of		interconnect	and	speaker	cables	from	left to
right	should reveal	the malfunctioning component.

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