Ferrograph F 307 Service Manual

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FERROGRAPH

F307 AMPLIFIER

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F307 SERVICE MANUAL

There are one or two additional items for the F307 Service Manual,
and these are given below. it is suggested that this sheet be inserted in
the Manual with a note on the appropriate page, or each paragraph could be
cut and inserted on the actual page.

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The 'onl lamp is powered from the main 70V D. C. line which also
supplies the power amplifiers. A sudden surge of near maximum power to
the loudspeakers may lower the supply voltage momentarily and cause the
lamp to flicker. This ls quite normal, although of course it should only
occur when the loudspeaker is driven by a loud signal, usually low frequency.

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in the second last line of "Note", the small resistor should be
approximately 109-209.

Tage Reel ax inputs

Although not specifically stated in the text or indicated in diagrams .
Figs. 4 E; 5, the Tape Replay inputs are controlled by the Mode Selector t
buttons (Left, Right, Stereo) in the same way as the other inputs. in each
channel the level of signal is still controlled by the Tape Input potentiometer
(Left or Right), and therefore these must be at maximum (fully clockwise)
when measuring the input sensitivity.

Fig. 4 - MONO

in MONO operation with the Leftl button pressed, the Left Tape
Replay signal is connected to both inputs, and similarly with the Right
button pressed the Right Tape Replay signal is connected to both Tape Replay
inputs. Note that the Tape input potentlometers still control the signal
level of each channel.

Fig. 5 - DUAL MONO

in DUAL MONO operation with both lLeft' and lRightl buttons pressed,
the Left and Right Tape Replay signals are in parallel and connected to
both inputs. Note that although both channels carry the same combinedl
signal, the Tape Input Potentiometers still control the signal level of each
channel.

Page 45

(3)

-2- R10

Jamming of one or more of the idler wheel arms (35A, B or C) could
occur if the recorder has received a slight mechanical shock, e.g.

in transit, such that the slotted support brackets (37A or B) are not
at right angles (approximately) to the run of the idler wheel arms.
Releasing the bracket screws and resetting the bracket usually effects
a cure. It is also worthwhile examining the thin sides of the idler
wheel arms for burrs (rough protrusions) which may prevent the arms
from riding freely in their slotted brackets. Any burrs should be
gently removed using a small file.

i'

incorrect adjustment or tension on the speed selector spring (588)
may prevent the idler wheel arm from engaging or result in the idler
wheel disengaging from the motor pulley/flywheel. This can usually
be cured by undertaking one or more of the adjustments outlined on
page 52 (para 405) of the Series 7 Recorder Service Manual (500-010)
or Maintenance Manual (500-016).

Should a fault of this nature occur at only the\highest tape speed the
speed selector spring (588) may be chafing the deck plate and in this
instance it will probably be necessary to adjust the height of the speed
change cam (638). However, adjustment of the cam must be carried: '.-
out with care otherwise the speed selector spring (588) may not align
itself in each idler wheel arm slot.

8. CAROLINE
Service Manager

For Service Mnnunll
MAURI'I'RON SERVICE
8 Cherry The Road, Chlnnor
Oxfordnhlre, OX9 JQY.
Tel 01844) 351694
Fax (01844) 357.554
email:- sales@mauritron.oo.uk