Philips VG-5000 General Maintenance

Component-side layout of the cassette interface board (top) and the main board, with the connector pinouts, from page 6 of the Service sa service manual.

The Philips VG-5000 is simple to open and has no internal mains supply: it runs from the external VU-0022 power supply. The Service sa service manual for the computer has no adjustment procedures, so routine work is cleaning, re-seating and the occasional repair to the cassette socket. Most of the practical detail below comes from the VG 5000 Bazar repair notes, whose author repaired several machines and supplies.

Safety

The computer itself only sees +5 V, +12 V and -12 V from the supply. The VU-0022 is a switch-mode mains supply: its reservoir capacitors charge to about 310 V, and the service manual notes that the hatched printing on the board marks the parts connected directly to the mains. Unplug it before opening it, and leave time for the reservoir capacitors to discharge.

Opening the computer

Taking a VG5000 apart (VG 5000 Bazar)

Step	What to do
Top case	Turn the machine over and remove the three cross-head screws in the wells underneath. Turn it back, and lift the top case from the rear, pressing on the top of the keyboard. It should come away easily.
Keyboard	The keyboard simply rests on two foam-covered ledges. Lift it, slide it forwards to reach its ribbon cable at the main board, and pull the ribbon out gently by its edges.
Cassette board	The small board on the left is held by two plastic hooks. Push the hooks while lifting the board a little, then slide it towards the main board; the ribbon between the two boards is stiff, so expect some resistance.
Main board	Two tabs hold it at its left and right edges. Lift the board slightly beside each hook while pushing the hook outwards, then pull the board backwards.

The hooks are not brittle if handled gently.

Ageing parts

• The adhesive on the serial number labels hardens; the VG 5000 Bazar author re-fixes them with a white glue stick.
• The foam blocks between the keyboard and the case crumble and turn sticky. They can be removed; the keyboard stays in place without them.
• Connectors that have been plugged and unplugged many times develop cracked solder joints; the VG 5000 Bazar author found this twice on the cassette socket. See Philips VG-5000 Troubleshooting Guide.

Socketed chips

Most of the main chips are in sockets, and the parts list includes 28-pin and 40-pin IC sockets. To lift a chip, slide the tip of a small flat screwdriver under one end, kept flat to the board, then the other end, and repeat with a larger screwdriver while pulling the chip up with two fingers. The EF9345 is the awkward one, particularly on the second version of the main board, because resistors sit close to two of its sides. All the chip markings on the board face the same way, which helps when refitting. Philips's own mechanical check is to inspect the solder joints for shorts and to check that the connectors and the chips in their sockets are properly seated.

Television set-up

The service manual gives a BASIC program that draws a standard colour bar pattern and plays a continuous tone, for setting up the television (for example when a colour encoder or modulator is used). The pattern takes about fifteen seconds to appear.

05 PRINT "Un instant S.V.P."
10 FOR L = 16384 TO 18304 STEP 80
20 FOR M = 0 TO 79 STEP 10 : READ C
30 FOR N = 0 TO 9 STEP 2
40 POKE (L+M+N) , 127 : POKE (L+M+N+1) , C
50 NEXT N : NEXT M : RESTORE
60 NEXT L : PRINT
70 SOUND 255,255,4
80 GOTO 70
90 DATA 7,3,6,2,5,1,4,0

VU-0022 power supply

The supply opens by removing the four cross-head screws in the wells at its corners and lifting off the light grey cover. To take the board out, unplug the lead from the on/off switch (spread the horseshoe-shaped catch and pull the grey plug) and lift the switch out of its housing. There are two versions of the board: the earlier one has two large reservoir capacitors, the later one, made from mid-November 1984, only one. The only adjustment is R168, set for 5 V across the output capacitor C201. Checks and the common failure are on Philips VG-5000 Troubleshooting Guide and Philips VG-5000 Capacitor Replacement Guide.

VY-0030 cassette recorder

The VY-0030 is the cassette recorder most often sold with the VG5000. Its drive belt hardens and stretches with age, so the tape runs slowly and loading becomes unreliable or fails. The VG 5000 Bazar author uses belt CR-118/12 (74 mm diameter, 1.2 mm thick) and reports the same mechanism in Exelvision, Matra Alice and Yeno recorders and in the Schneider TR3644 and TR3645.

Changing the VY-0030 belt (VG 5000 Bazar)

Step	What to do
Top cover	Slide off the battery cover, remove the four screws underneath (one is longer and goes back in its own hole), open the cassette door and free the small rectangular block above the power lead. Lift the top off and unscrew the small LED board from it.
Mechanism	Remove two screws (one beside the motor, one on the metal plate near the counter), lift the mechanism out from the motor end and turn it over. Remove the two screws on the circuit board and the screw at the end of the triangular metal plate above the main wheel.
Belt	Lift the circuit board slightly and take off the old belt. Fit the new one round the large pulley on the right first, then the small white plastic shaft on the left, then push it onto the pulley under the circuit board with a small screwdriver. It must not twist, and it must run over the small green pads beside the motor shaft.
Reassembly	Do not pull on the fine wires; if the mechanism resists going back into the case, a wire is caught underneath.

Related pages

• Philips VG-5000
• Philips VG-5000 Troubleshooting Guide
• Philips VG-5000 Capacitor Replacement Guide
• Philips VG-5000 Documentation