Grundig TK 148 Service Manual

Page 1

TK 148 Automatic

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TK 148 Automatic

Service Information
Numeere in ( ) in the text refer to numbers in the spare parts list fur the TKlAB.

Hard or metallic/magnetic ebjects should not he brought into contact with the heads
as this may cause damage.

F191 Remowih To Cover and Houein 57

Remove the five screws (91) the handle (m2) and the handle securing screw
(94). pull or? the speed change lever (104), the record button (99), the
functiun lever (97) end the knots (lul), taking care not to lose the felt
pads. Pull off the functian lever (95) and the top cover (57) can ta removed.

rig 2 Remevin Base 92
Ramnving the fnur screws (a) pull the mains ceole through the cable

compartment. Remove the case (92) letting the cable slide through the outlet
hole.

Fig 7 AmEllfiar Printed circuit Board (11)) - solder side
After removing the housing (87) (as in rig l ) undo the two screws (b) and pull
the screening plate (rum it'a key way.

rig 5/7 Amplifier Printed Circuit Board (llu) . component side
Dismantle both the top cover screen and the base. Gently pull out the control

printed circuit toerd (145) aFtar bending away location flap: on top a? chassis.
Remove the screw (c), and pull the printed circuit ooerd (lie) down and out.

NOTE:- The functiun aalactlun lavar ahnuld be in the "START" peeitiun

rig l/7 Servicing the Heads end sound channel

Rameve the head cover (em), and clean the heads. tape guides and sound channel
with methylated spirits.

Fig 7 changing and Ad ueting Heede
(fer securing screws, eee illustration). Adjuatmante are made using Grundig
Alignment Tape 116A. The vertical height of the record/playoack heed is made
with screw (h). azimuth adjustment with screw (n).

Fig 5/5 changing the salts
Fully dismantle the mechina,ramove the acrews(d),and take the tearing(A9) eff
the {lywhasl aplndle.Lift the belt cut end ever the epindle(ee in Fig E).Tha
belt (:1) can now be pulled out.

rigs/4 clutch Torgue
The illustration shows the torque measured on the clutches.

Fig 7 Tags Drive

with the pressure bend removed the tape must travel over the capstan spindle
without leaping Adjust after loosening screws (a).

rig 3/7 pressure Roller

In the "PAUSE" puaitinn the pressure roller must be parallel with the capstan

spindle. In the "START" position the pressure rnllar must take from 3-6 revnlutians

to travel frem the top to the buttnm position. Adjust with adjustmant kay
seee-nss ertar loosening screw (c). The pressure cf the pressure roller on the
capstan spindle in the "START" position should he 7ungr 4 mi, adjust with
screw (9).

Fig 5

Fig 5

Pressing the record button in the "automatic mode should nut mnva :nntact "a1",
and with "Trick" depressed, the Contact tt1 must meve 0.2mm to make.

The and D? the tape stop is so adjusted that in the STOP","PAUSE", and in the rest
position between "START" and rest Parward wind the nose of the switch lever has
a clearance of U.3-u.5mm from the senators piece.

correct arter loosening the securing screw (1').
Bias Setting ( need only be carried out if heads are changed )

Switch the machine to "menu", "MANUAL", "DAUSE" and with a capacitive voltage
divider (i.e. VSTZA) connected to test point (tracks l-Z) or ( tracks
3-4) on the track switching printed circuit board T. Adjust the plea voltage
with cans according to the colour coding in? the head :-

Rad 32V - Iuhite 36V - Black MJV - Yellow 4M!

Heads which have two colour codes should he adJuatad in the "arithmetical centre"
i.e. slack/yellow = 42v (when the "TRICK" button is depressed the bias voltage
should drop by 2.5V).

The areas voltage measured at v or w should be at least law.

The hiss/erase frequency (measured via er) should lie between 52 and 7dkHz.
(when the "TRICK" button ie depressed the frequency should fall by 15$).

Measurements Ueih Grundi Ali nmant Ta a 9 1 a 458 at 9 cm s 3
The eutput er the 333H1 section of the tape measured at pins 3/2 D? the "radio"
ancket must be SflDmV from aach track.

The output at other rreouenciea must lie within the Fullnwing tolerance field
(to DIN 45 511 ). if the deviation at 12.5kHz is excessive the head alignment
should he chackad.

Recurding and Plazbenk
Input Vie 47mm in parallel with lSDpF to pins 1/2 of tha radii: auckat.
jull Eacnrding Laval

Set the machine to Recurdmutnmatic, 9.5 cm/a (3i i.p.a ), sashz. Vin - 20mm].
The playback voltage under these conditions should as at least SCION/with a
distortion rector k or A-sx. The voltage measured at v should be 4v ; 1.5de,
adjustahla with R113 whilst making a new recording.

when these conditions are fulfilled, the recording level indicator can be checked.
The lamp under the red riald must only Just light. AdJuet with R509.

Fra uene Rea unsa at 9.5 cm s 3 l and 4.75 cm a 1 . .5.

(Machine switched to Manual)

Record e test tape at eeeh speed with an input nf ZDIIIV at all Frequencies.
During playback the levels aheuld lie within tha following tolerance fields.
If there should be any loss at 12.5kHz the HF blaa paint ahuulfl be changed slightly

ADHz ZEDHz AkHz 12.5khr mm 25%: Akhz 5.3km

HdB 6:13 8-15 ede Gde Eda

Tolerance Field to DIN 45511 Record/hapley response
a. Record/Replay response a 9.5 em/s at 4.75 cm/s.

Automatic marking Point

switch machine tn Nicene", "AUTDMATIE", "PAUSE". Place a short across resistors
RluA-Rms, and connect a DI: voltmeter to points v V . Sat nine for a reading
0? 0.5V.