Jump to content

Philips VG-8010 Troubleshooting Guide

From RetroTechCollection
Philips VU-0022 power supply circuit diagram
The VU-0022 supply used by the VG-8010, from its Philips service manual

Faults on the Philips VG-8010 split between the external VU-0022 supply, the main board and the encoder board that produces the video signal. Component references are those of Philips's service manual for the VG 8000 and VG 8010.[1] Adjustments and opening the case are on Philips VG-8010 General Maintenance.

Warning: the VU-0022 is a switch-mode mains supply with about 310 V on its reservoir capacitors. Unplug it before opening it.[2]

Symptoms

[edit | edit source]
VG-8010 symptoms
Symptom Probable cause Action
Power LED off VU-0022 output capacitor C203, fuse, plug or lead Measure the supply off the computer
Power LED on, black screen; starts after pressing reset Reset circuit, corroded tracks See Black screen at switch-on
Power LED on, black screen A supply rail out of range, RAM, ROM Check the rails, then the board
Noisy or shaking picture Partly by design; supply and video capacitors See Poor picture
No colour or wrong colours Pins between the main board and encoder board, PAL clock, TDA2501 See Colour faults
GRAPH or CODE seems stuck Normal: both keys toggle Press the key again

[3][4][5][6]

Supply checks

[edit | edit source]

Measure the supply first, with the computer unplugged from it, so that a supply giving too much voltage cannot damage the computer.[3]

VU-0022 output
Rail Rated output Measured on a working supply (VG 5000 Bazar)
+5 V 1.55 A About +5.2 V
+12 V 100 mA About +11 V
-12 V 100 mA About -11.4 V

[7][3]

  • +5 V erratic and +12 V well below 11 V: the 4700 µF output capacitor C203 has very likely failed short. On the Bazar supplies it was warm to the touch. Replacement is on Philips VG-8010 Capacitor Replacement Guide.[3][2]
  • +5 V present but not 5 V: set R168 for 5 V across C201.[8]
  • -12 V low: one owner with a black screen measured +5.1 V, +11.8 V and -9.1 V from his VU-0022 and obtained another supply; the thread does not record the result.[9] On the -12 V side check C204, C205, D186 and R159.[2]
  • Supply dead: check the fuse VL213 (630 mA slow-blow), the switch and the mains lead, then the TEA1039 circuit.[2]

On the main board the three rails arrive through filter capacitors: C832 and C834 on +5 V, C833 and C835 on +12 V with the choke L461, and C836 and C837 on -12 V with L462. Measure across them with the computer running.[10]

If no VU-0022 is available, a bench supply can be used for testing. One member found that a VG-8010 sold as broken started normally with only +5 V connected to the board, and later fitted a 30 W triple-output switch-mode supply inside the case in the space left by removing the RF modulator.[11] The +12 V and -12 V rails are still needed for the sound and cassette circuits.

Black screen at switch-on

[edit | edit source]

If the machine shows a black screen when switched on but starts normally after the reset button is pressed, look at the reset circuit near the Z80 (IC652): TS400 (BC548B), the 74LS04 IC670 and the 7406 IC673. On one VG-8010 the cause was corroded tracks in that circuit.[4]

If reset does not help:

  1. Check all three supply rails on the main board (above).
  2. Check that the socketed chips are fully seated and their pins are clean.[12]
  3. Check the 32K RAM board and its two connectors. On the VG-8010 all the user RAM is on that board.[12][13]
  4. Try the composite output and the RF output in turn; a fault in the encoder board or modulator can leave a working computer with no picture.

Poor picture

[edit | edit source]

A noisy picture is common on this model. sdsnatcher73, who has seen several VG-8010s, puts it down to the design of the VG-8000 and VG-8010, and Manuel found that leaving a machine switched on for a few hours improved the picture considerably.[4] Capacitors still play a part: one owner found that recapping the VU-0022 reduced the noise, and another that replacing the electrolytics in the supply, main board and encoder board made a shaking picture steadier.[4][5] The VG 5000 Bazar author notes that some VU-0022 supplies cause a wavy picture that replacing C203 does not cure.[3]

Colour faults

[edit | edit source]
  • Black and white only: check the pins and connector between the main board and the encoder board. In mjnman's machine some were broken, and with the R-Y signal interrupted the picture had no colour. Replacing the TDA2501 had not helped.[5]
  • Wrong or drifting colours on the /00: set the PAL clock with C900 for 4.433619 MHz at pin 3 of IC721.[8] Some encoder boards use an oscillator circuit (IC672, X872, C903) instead of crystal X871.[14]
  • /19 (RGB): the encoder has one adjustment, R576, for 2.5 V at the junction of R557 and R558.[8]

Cassette and sound

[edit | edit source]

The cassette motor is switched by TS398 and TS399 from the 8255. The cassette output is taken from the 8255 through R219, R218 and C819; the input is squared by an LM311 comparator (IC665) on the encoder board, so a cassette input fault can be on the encoder board as well as the main board.[10] The VG-8010 has no separate audio output; sound reaches the television through the modulator or the monitor socket.[6]

[edit | edit source]

References

[edit | edit source]
  1. ↑ Philips, Service Manual, Home computer VG 8000/00/19/20, VG 8010/00/19, PDF page 1. Hosted as File:Philips VG-8000 VG-8010 Service Manual.pdf.
  2. ↑ 2.0 2.1 2.2 2.3 Philips, Service Manual, Home computer VG 8000/00/19/20, VG 8010/00/19, PDF pages 11 and 12, external power supply unit: VL213 (630 mA T) and filter S207 on the mains side; bridge D224 to D227 (BYW55) and reservoirs C196 and C197 (22 µF 385 V) at about 310 V; IC192 TEA1039 controller and TS190 BUX84 switching transistor on transformer T211; outputs 5 V (D189, C203 4700 µF 10 V, S210, C201 330 µF), +12 V (D187, C200 330 µF, S209, C199 220 µF) and -12 V (D186, C204 150 µF, R159 1 Ω, C205 47 µF); regulation through the CNX62 optocoupler U191 and trimmer R168. Hosted as File:Philips VG-8000 VG-8010 Service Manual.pdf.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 VG 5000 Bazar, "Dépanner une alimentation VU-0022", version 1.0 of 17 March 2018, revised 3 February 2025. http://vg5000bazar.free.fr/html/depannage/vu0022.htm In French. Symptoms of a failing supply on the computer: the red power LED does not light, flashes, or comes on dim and brightens slowly; a buzzing from the supply. Output voltages of a working supply about +5.2 V, +11 V and -11.4 V; in three failed supplies the +5 V output was erratic, the +12 V below 7 V and the -12 V normal, and the 4700 µF capacitor beside the output cable was hot and short-circuited; replacing it repaired all three. On two of the three, one lead of that capacitor had come loose; resoldering it repaired a fourth supply. The fuse and switch had not failed in any of them.
  4. ↑ 4.0 4.1 4.2 4.3 VG8010/00 - Video noise and power up trouble, April to November 2023—link(accessed 2026-10-21) emilen72: a VG-8010/00 stays on a black screen at switch-on and starts after a reset, with noisy RF and composite video; recapping the VU-0022 reduced the noise, and an ATX-based supply did not remove it. sdsnatcher73: of the VG8010s he has seen, all had relatively bad video; one had the same reset fault, fixed by Alexey, caused by corroded tracks in the reset circuit; poor video on all VG8000 and VG8010 models is a design issue and not only capacitors; he has seen machines with no video come to life after being left on. Jipe: the functional diagram shows the reset control near the Z80 (IC652) with TS400 (BC548B), IC670-2 and IC670-3 (74LS04) and IC673-4 (7406N). Manuel: leaving a machine on for a few hours greatly improved the picture.
  5. ↑ 5.0 5.1 5.2 Philips VG-8010 with bad video quality, November and December 2023—link(accessed 2026-10-21) mjnman: a VG-8010 with a shaking picture; replacing all electrolytic capacitors in the supply, main board and PAL encoder board made it steadier but the colours were wrong; a new TDA2501 gave black and white, as did refitting the old one; solved by repairing broken pins between the main board and the PAL encoder board, since interrupting R-Y loses the colour.
  6. ↑ 6.0 6.1 Philips VG-8010, MSX Resource Center wiki—link(accessed 2026-10-21) GRAPH and CODE work as toggles on both versions; external VU 0022 supply.
  7. ↑ Philips VU 0022, MSX Resource Center wiki, 21 February 2024—link(accessed 2026-10-21) Rated outputs 5 V 1.55 A, +12 V 100 mA, -12 V 100 mA; input 220 V 50 Hz; proprietary DIN connector.
  8. ↑ 8.0 8.1 8.2 Philips, Service Manual, Home computer VG 8000/00/19/20, VG 8010/00/19, PDF page 2: power supply voltage, adjust R168 for 5 V across the output (C201); clock frequency /00 and /20, counter on pin 3 of IC721, C900 for 4.433619 MHz; modulation depth, C901; UHF channel 32, adjustable 31 to 33 with L650; /19 voltage, R576 for 2.5 V at R557 and R558. Hosted as File:Philips VG-8000 VG-8010 Service Manual.pdf.
  9. ↑ problems with VG8010, July 2007—link(accessed 2026-10-21) msxrestarter: a VG8010 with the red power LED lit and a black screen; the VU-0022 measured +5.1 V, +11.8 V and -9.1 V; he found another VU-0022 to try; no result posted.
  10. ↑ 10.0 10.1 Philips, Service Manual, Home computer VG 8000/00/19/20, VG 8010/00/19, circuit diagrams: PDF page 21, supply input from the power connector BU-G with C832 and C834 (150 µF) and C796 (4.7 nF) on +5 V, C833 and C835 (68 µF), L461 and C797 on +12 V, C836 and C837 (68 µF), L462 and C798 on -12 V, the power LED D896 (CQV60A4) through R208 (330 Ω) from +5 V; PDF page 24, reset lines through IC673 and IC687, cassette motor switch TS398 (BC548B) and TS399 (BD140) from PPI port C bit 4 with diodes D345 and D347, cassette output from bit 5 through R219, R218 and C819, caps LED D898 from bit 6 through IC676 and R191; PDF page 25, code LED D897 from the PSG and the cassette input comparator IC665 (LM311) on the encoder board (U100-B). Hosted as File:Philips VG-8000 VG-8010 Service Manual.pdf.
  11. ↑ Power supply for Philips VG-8010 MSX, May 2019—link(accessed 2026-10-21) Wierzbowsky: a VG-8010 sold as broken without its supply booted normally with +5 V connected to the board; the power connector is non-standard; he removed the RF module and fitted a 30 W triple-voltage (+5 V, +12 V, -12 V) switch-mode supply inside, with ventilation holes and an extra aluminium heat sink, and found minor interference on composite video; the /00 has no RGB output. gdx: an MSX1 without disk drive rarely draws more than 25 W, mostly on +5 V.
  12. ↑ 12.0 12.1 Philips, Service Manual, Home computer VG 8000/00/19/20, VG 8010/00/19, PDF page 15, mechanical parts list: IC sockets (28 and 40 pins), keyboard socket (18 pins), power supply connector (5 pins), reset push button; connectors of the 32K RAM circuit (4-way and 9-way). Hosted as File:Philips VG-8000 VG-8010 Service Manual.pdf.
  13. ↑ Philips, Service Manual, Home computer VG 8000/00/19/20, VG 8010/00/19, PDF pages 3 and 4, specification of ICs: user RAM IC657 and IC658 on the VG 8000 only; VG 8010 RAM board IC662 to IC665 (TMS4416-15) and IC666 (74LS74AN, CAS1 and CAS2); video RAM IC660 and IC661 (TMS4416-20NL); BIOS ROM IC663 (23256AC); refresh counter IC714. Hosted as File:Philips VG-8000 VG-8010 Service Manual.pdf.
  14. ↑ Philips, Service Information CT85-2, 7 February 1985, VG8000/VG8010 (PDF page 18 of the service manual): in some versions crystal X871 on the PAL/CVBS encoder is replaced by an oscillator circuit. Hosted as File:Philips VG-8000 VG-8010 Service Manual.pdf.



Retrieved from "https://retrotechwiki.com/index.php?title=Philips_VG-8010_Troubleshooting_Guide&oldid=28129"