Akai M8

XI
TROUBLE
SHOOTING
CHART
FOR
MODEL
M-8
SECTION “A” TROUBLES WITH AMPLIFIER
1.
Playback
problems.
(Unit
set
in
play
position.)
No
sound
from
5
Vacuum
tube(s)
loud
does
not
light
Defective
power
transformer.
Check
and
replace.
Check
and
replace.
‘uum
tebe(s)
om
iow
loca
-
-
:
ms
okay.
Head
coil
bumed
out
Check
and
replace.
Defective
top
or
2nd
stage
tube
(V1,
V2)
Defective
85,
R6.
R7,
RO,
#10.
Ri2,
R12.
Ri3,
or
215,
Check
if
voltages
correct,
and
Teplace
resistor]
No
speaker
hum
Output
transformer
burned
out
Check
aad
replace.
Speaker
voice
coil
burned
out
Replace
speaker,
Defective power output tube. {¥3)
Defective
R17.
Check
voltage,
and
replace.
Sound
from
speaker
but
insufficient
Defective
V1,
V2,
V3.
or
V5.
Replace
tube.
volume.
Clean
heads
gently
with
cotton
swab
No
change
after
tubes
replaced.
Des-oait
of
dust
on
head
soaked
in
rubbing
alcohol
:
:
Recording
tape
deing.reversed.
Cueva
od
correct
tape.
|
Sera
aC
een
f
Pera
|
B
(+)
voltage
low.
Check
C26.
Tnspect Chokecou (L3) and replace.
Defective
resistor{
s)
and/or
capacitor(s)
in
circuit
Check
voltages,
and
replace
defective
one
(8)
Tncorrect
polanty
of
ght
Channel
amplifier.
Reverse
polanty
of
AC
plug
20
ngnt
axpii:
}
Sound
from
speaker
dat
with
(Hum
controllable
with
volume
controb
Defective
Vi
or
V2.
Replace
V1
or
V2,
lord
hum.
VL
¥2
inpat(erid)
lead
wires
isproperly
Positioned.
Dress
reposition
input
lead
wires,
.
et
te
—
:
on
ee
”
Head
TL.
¥2
ground
mre
inproperty
positioned
Dress
ground
wire.
fdum
not
controllable
with
volume
control
Defective
¥2
V3
Replace
V2;
V3.
Defective
C26,
Ll
or
C8
C17
-~oher®
C28,
LL
Ca
17]
Hum
reduced
when
playback
head
shorted.
Shielding
on
playback
head
aot
perfect.
Replace
head.
Leakage flax froa sotor or froz poser transformer.
Check motor and pove: transformer,
Teplace if necessary.
Read just bum ducking cow
Hum bocxing coil cut <f ccstment.
Unit picks up external aagactic flux.
Ground recorder at carstan storage post.
Reposition recorder.
Shield recorder.
Hoa
only
when
playing
tape,
no
hum
without
tape.
Hum
recorded
on
tape.
Renew
recording.
Noise
level
controllable
with
volume
control
Defective
V1,
V2
Replace
V1,
V2.
Defective RL R6&. Re or Ril. Check Rl, R6,RS8 or R11 and replace.
Noise
level
not
controllable
with
volume
control.
Defective
V2,
V3.
Replace
V2,
V3.
Defective C18, Cl4 or C15 in NF circuit. Check C13, C14, C15 and replace.
Output
trausforser
being
burned
out
Check
and
replace
output
transformer.
————__.
Defective C27. Lz in B(+) circuit.
Check C26, Li replace dafective parts.
Uneven coating on recording tape.
——
Replace recording tape with new ore. }
ng head desscmetizer
Intermittent noise.
Constant background noise
from speaker.
Noise only while tape is deing played.
Desaguetize heads
Replace V1, V2.
Check R6. ALL R13 and replace.
Tape heads being maynetiied.
Defective Vl. ¥2.
Nowe with or without tape on recorder.
Defective R6. Riior R13.
Check C5. C6,C?7, R14, R4 and replace.
Lack
of
base.
Defective
CS, C&, C7,
Rl4.or
RS.
Defective
recording
tape.
Recording tape in close contact mth tape heads.
Record/play head wis-aigned. (Azimuth
alignment of gap in recording haad.)
Worn-out tape heads.
Detective V1. V2 or V3.
Replace recording tape.
Clean tape heads.
Check supply recl shaft assendiy and
readjust spring tension.
Dust on tape beads.
Lack of treble.
Weak back tension.
Re-alugn head using standard alignment tape.
Replice bead assorbly.
{Replace Vi. ¥2 or V3 and test.
| Check component parts im circurt by mea-
aumng voltage. See wimg diagram fcr re-
gular volatge.
Replace loud speaker.
Sound disturted.
Incorrect cucuit rating.
Defective loud speaker.