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Servicing Hints - Philips D2935 Service Manual

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SERVICING
HINTS
Remove
rear cover
See Fig. 1. Loosen the 5 screws D and remove the rear
cover.
Pay attention to the telescopic antenna connection.
When this connection has been detached, the rear cover
can be folded down.
Diagnosis Analogue-Digital Failure
Introduction
The receiver is digitally controlled by uP6301
(MSM5840H-91RS). This uP incorporates a service test
programme enabling to check the digital part of the
receiver. By measuring the tuning voltages (table: V-
tuning voltages) the output of the digital section can be
checked.
Service test programme (see Fig. 2)
1. To bring the receiver in the service mode, pin 16 of
u P6301 should be connected to the negative (A204)
of the power supply voltage. For that purpose pin 16
has been brought from the uP unit to the main PCB
and made accessible (connector A201).
Actuate on/off switch.
The receiver tunes to FM 87.50 MHz.
Display 1301 alternately shows FM 87.50 MHz or the
other segments (see Figs. 3a and b). In this way the
LCD display is checked in all its segments.
5.
At connector A203 (V-tuning) a voltage of +1.7
+ 0.4 Vis applied.
At connector A206 (FM/AM) a voltage of +0.7 V is
measured.
At connector A207 (+2) the +2 power supply voltage
is applied.
At connector A208 (Mute) appears a voltage of
> +4 V.
At other pins of connector A20. no signal is applied
and O V is measured there.
6.
Via data lines DLEN/DATA 0, DLCD/DATA
1,
DATA 2 and DATA 8 signals are transported to the
synthesizer in data flows.
7.
If the connection between the negative and A201 is
eliminated, the uP will leave the service mode and
the receiver will once again function normally.
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Servicing the Analogic Circuitry PCB (see Fig. 2)
Remove the 7 screws of the face screen and remove
the screen.
Unsolder the 2 wires of ferroceptor 1012. (B)
Remove the "BFO" and "Gain Control" knobs.
Undo the 5 screws C.
Now the Analogic Circuitry PCB can be detached.
Servicing the uP control unit
After the Analogic Circuitry PCB is detached, the uP
contro! unit is accessible.
Remove the 7 screws of the face screen and remove
the screen.
If connector A20. is loosened as well, the P contro!
unit cannot function.
To this end, C325 and C326 should be connected to
the +2 supply voltage via a pull-up resistor. Select a
pull-up resistor of 100 kN.
Furthermore connect C327 to +2 (+5 V) and C324 to
the chassis of the power supply.
The 54532 kHz oscillator
In case ofrepairs to, or derangements of the 54532 kHz
oscillator, the oscillator can be brought in a stable
condition again by means of coil 5106.
The adjustment takes place as follows:
Set apparatus in the AM position.
——
Use a frequency counter to measure on pin 14 of
1C6100 (TK10311) whether the oscillator frequency,
54532 kHz + 1 kHz, is present.
Set adjusting capacity 2133 in mid-position.
Bring the core of coil 5106 in the centre of the coil.
Turn this core clockwise and downwards until the
oscillator stops functioning.
Now turn the core anti-clockwise and upwards until
the oscillator starts to function again.
The oscillator is now in a stable condition. Small
deviations from the indicated frequency have no
influence on the proper functioning of the apparatus.
CNL) SERVICE WENKEN
Verwijderen achterwand
Zie Fig. 1. Neem de 5 schroeven D weg en neem de
achterwand af.
Let op de telescoopantenneverbinding. Nadat deze is
weggenomen kan de achterwand worden neergeklapt.
Diagnose Analoog-Digitaal Fout
Inleiding
De ontvanger wordt door uP6301 (MSM5840H-91RS)
digitaal gestuurd. In deze uP is een service test
programma opgenomen, waardoor het mogelijk wordt
om het digitale deel van de ontvanger te kontroleren.
Door het meten van de afstemspanningen (tabel: V-
tuning voltages) kan de uitgang van het digitale deel
worden gekontroleerd.
Service test programma (zie Fig. 2)
1.
Om het apparaat in de service mode te brengen,
moet pen 16 van » P6301 met de min van de
voedingsspanning (A204) worden verbonden. Pen
16 is daarvoor vanuit de uP-unit naar de hoofdprint
gebracht en bereikbaar op connector A201.
Schakel aan/uit schakelaar in.
Het apparaat stemt nu af op FM 87.50 MHz.
De display 1301 geeft nu beurtelings: FM 87.50 MHz
of de overige segmenten weer (zie Fig. 3a en b).
Hiermee wordt de LCD-display op al zijn segmenien
gekontroleerd.
5.
Op connector A203 (V-tuning) wordt nu een
spanning van +1,7 + 0,4 V aangeboden.
Op connector A206 (FM/AM) wordt een spanning
van +0,7 V gemeten.
Op connector A207 (+2) wordt de voedingsspanrning
+2 aangeboden.
Op connector A208 (Mute) staat een spanning
> +4V.
Op andere punten van connector A20. wordt geer
signaal toegevoerd en wordt 0 V gemeten.
6.
Via de data linen DLEN/DATA 0, DLCD/DATA
1,
DATA 2, DATA 3 worden in datastromen signalen
naar de synthesizer getransporteerd.
7.
Als de verbinding van de min met A201 opgeheven
wordt, komt de uP uit de service mode en zal het
apparaat weer normaal funktioneren.
& ON
Servicen van de "Analogic Circuitry PCB" (zie Fig. 2)
Soldeer de 2 draden van de ferroceptor 1012 los 3).
Verwijder de 'BFO" en "Gain Control" knoppen.
Neem de 5 schroeven C weg.
Daarna kan de "Analogic Circuitry PCB" worden
losgenomen.
Servicen »P stuurunit
Nadat de "Analogic Circuitry PCB" is weggenomen, 5
de z»P stuurunit bereikbaar.
Neem de 7 schroeven van de afschermdeksel wegen
neem het deksel af.
CS 98 63
7 a

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D2935/00D2935/02D2935/05D2935/19