Ferrograph 631 Owners Manual

Page 40

F»; is eowtit UNIV uNDIiIDG I'IIN

While this is designed to give as pure a waveform as possible, under certain circum-
stances individual components of the residual distortion may occasmnnlly beat with the
local Oscillators of radio sets during recording if adequate spacing and screening precau~
tions are not taken. The remedy n nl course to ensure that the DCIIII and other leads
to the receiver are not taken close to the ranrder itself.

The output of the oscillator is taken tn the heads «in the deck via the Era: mt! Super-
impmitiou Links on the mr panel. for the purposes previously mentionntl in Section 10

18.3. e Amplifier
The amplifier is used both on record and playback but is \Ultlbly SWIKLhLd an the
deck. For simplicity. thae openuons are described separately.

Ramirtvul 0/ Amplifltr {mm (.dlflkl

This involves prising ofl the metal cover of the handle hinge on the front uf the
cabinet and ramming (ht: liiur screws uni! handle complete. The four screws at each
corner of the amplifier panel should be undone. and also the twu serevn mt each \idc of
the case holding the cum strap behind thts pIneL The two deck holding bolts should be
loosened and the deck raised. The amplifier and mm map can now he moved. The
clip holding the lead to the power unit should be unfastened and the amplifier front
can now be exposed. To remove it entirely tmm the cabinet the «created lad tn the mt
nova] socket must he unsoldernl.

Page 51

D. The position of L2.
E. The poaitim of the microphone matching motfottoer ( if one it used).
F. The polarity of the mains input.

The presence of hunt is most easily detected by a sensitive meter, or a athode
ray tube with on amplifier, connected aunts Pins 3 and 7 ofthe auxiliary socket.
Auyodiusmienttlwuldbemdewhilethemotononthededatetunuingesthis
is the proper condition of phyla-ct, but care should be taken to see that there is not
too great a dilletenoe between the reading: with the motors running and with the
mom stopped, as this will indicate that hum bucking is taking place, in. that some
humisbeinginiectedinanti-phasetothatarisiugfmwmeotherpnoftheequip-
meat. With full amplifier gain, the hunt voltage should not exceed 0.5V R.M.S.
with the motots both running and stopped.

Ausefulmethodofobtainingaminhnumfiguteisbyvvyingtheanglethe
mumml wing on the playback head pressure pad um makes with the tape. The
only pteeauuou mt)! in adjusting this is to ensure that the pressure pad contact
am is not adversely allotted.

The position of L2 an be Alta-ed by loosening its clip and rotating. although
thiuhouldnothcdonetoodnsticallyortheleodstoitmaybtuk. Although oulya
secondaty (me, it will have slightly mm efl'ect at 33 and ll in. Cm.

Thepoluityofthetnainsconnectionoanalsobedwckedasthixsomctimes
efl'ectsadaiuhleteduetion.

"M Signal to Nolae Ratio

Themwdgtundsignummoemioqmdinmupcdmmsmuuoot
theR.M.S.noisefmmtheetasedtapephnthehumcmteutoompandwiththe
R.M.S. signal output from a fully receded tape playing back at 3" distal-don.
nusmansthatthepaiuooutmltntbtnotheturuedtullydockwiseasthiswill
obviously ot'etload the amplifiet.

:0. USE As AN AMPLIFIER

While intended ptimarily for tape reproduction, the Ferny-IN" m be used as I
might" amplifier foiatuner unit or pidt-upbyuu-niugdtemain function switch to play-
hadL ll'thesigoalismwfedintolnpml«Zumnootdandthegainootmoladvamed,
itwillhehmdoumeintundspealtet,otenetnalspukerifeonnected. Anthetomoontrols
manly efl'eetiveontapeplaybock, the amplifiationwillbelinear.

:1. HEAD P081110)! 3
AsshowninFis.l2,heodpositim3isnomallyoccupiedbyadumtnyhad,buttheoctal

sodaismnueaedbymmeamdladswtheoutpmammthempmel

(Labelled STEREO OUTPUT). Any qugnph playback held may be plugged into this

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