Ferrograph Logic 7 Service Manual

Page 2

LOGIC 7 MAINTENANCE MANUAL 500-077

Errata & Amendments

Page Correction
31 Fig. 4 Head Alignment (Track Dispositions)

Fig. 5 Head Wiring

56 Item 15 Loading Arm Leaf Spring 714-022
30A Pinch Roller 025-112
30B Bracket Assy. 022-534
31A Pinch Roller Arm Assy. 022-444
57 Item 42 Brake Arm Pivot 025-439

58 Item 57 Take-up Reel Motor 022~250

Page 23

21

Check the condition and action of all return springs and replace
if damaged.

Check the operation of the tape deck, ensuring that the tape runs
smoothly and does not twist or curl in the guides. Check that
the tape height is correct across the head faces (Fig.4) and that
the tape runs reasonably centrally on the pinch roller. Check
that the reels do not scrape on the side frames and if necessary
adjust the height as in 3.4.3.

Check the recorder controls as follows:
Examine all switch and control knobs and ensure that they
are tight on their spindles.
Operate each switch in turn and ensure that the action is
positive.
Rotate each potentiometer in turn and ensure that the action
is smooth.
Check that all gain control knobs indicate zero when turned
fully off and also that the Bass & Treble knobs indicate
equally plus or minus when rotated to their extreme settings.
Visually inspect the wiring for signs of everheating and
ensure that all internal plugs and sockets are properly
mated.

Warning: Visual inspection should be carried out with the power
disconnected.

For more detailed examination of the tape deck operation and
setting up procedure see Section 4.1.

Page 26

No erasure.

Poor top response.

Poor bass response.

Excessive crosstalk.

24

Faulty erase head; check head and
alignment as in 4.2.4.

No feed to erase head; check record
oscillator and HT supply via RLlZS.

Heads dirty; clean heads as detailed
in 1.4.

Incorrect bias; check bias setting as
detailed in 4.2.4.

Incorrect head alignment; check head
height as in 3.4.9 and reset azimuth.

Faulty capacitor; check coupling
capacitors in amplifying stages; check
response of replay section by playing

a test tape, then check Source response.

Incorrect head height; check alignment
as detailed in 3.4.9.

RV700 faulty or incorrectly set; check
RV7OO & C714 and check setting as
detailed in 4.2.5.

Transfer switching faulty; check
operation of switches S704 & S705 and
replace if necessary.

Faulty connection; check wiring of
RV7OO and also the white & violet
leads to the Equalisation switch.

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41

NOTE: If tape other than BASF LP35LH is used, then the bias
should be set similarly then calibrated to the
appropriate meter reading as shown in Table 4.

Cancel Record and set the Record Mode switch to Upper.
Press Pause/Record and check that the bias reading does not
change.

If necessary adjust the bias balance control RV606 on the
Oscillator Board to return the bias to the correct reading.
Repeat for the Record Mode switch at Lower.

Table 4. Recommended Bias Settings (19 cm/s;7§ in/s)

Brand Type Bias
Agfa PE 36 -2
*PER 525 +2

Ampex 407 -1
Audiotape 907 -1
B.A.S.F. *LGR SOP +2
LPSSLH o

LPRSSLH -1

LPSSLH Super -2

E.M.I. 825 -1
Hidynamic -2

Ferrotape B -2
Maxell UDSS -1
Memorex -1
Scotch Classic 0
207 -2

223 -2

*262 +2

T.D.K Audua +1
SD 0

*These tapes are high output types intended for
use at 15 in/s and with these the recording level
should be allowed to rise to +3VU.

Page 89

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