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Intellivision II Capacitor Replacement Guide

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Intellivision II Model 5872 power supply board test points (Mattel)
Mattel's drawing of the Intellivision II power supply board (Figure 6). The drawing shows the parts but labels only the test points.

Capacitors in the Intellivision II, model 5872. Mattel's service manual gives the full logic board parts list, which has a single electrolytic capacitor. The power supply board, where most of the console's electrolytics are, appears in that list only as a complete assembly (part 5872-9539), and the manual has no schematic or parts list for it.[1] Mattel published no values for the power supply board capacitors. What the manual does show is below, with a method for recording your own board before replacing anything. See Capacitor Failure Symptoms for the signs of a failed capacitor.

Logic board

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Model 5872 logic board, electrolytic
Ref Value Rating Type Mattel P/N Position on the schematic
C19 4.7 µF 6.3 V Electrolytic 0085-0031 Reset circuit, with R9 (10 kΩ) to +5 V, diode CR3 and the reset switch S1

Value, rating, type and part number from the parts list; position from the schematic.[1][2]

The other logic board capacitors in Mattel's list are not electrolytics:[1]

Model 5872 logic board, other capacitors
Ref Value Mattel P/N
C1–C5, C7–C11, C13–C15, C18, C30, C33, C35, C36 0.1 µF 25 V 0085-1510
C16 20 pF 15 V NPO 0085-0720
C17 Variable, 5–50 pF 0099-0730
C20 220 pF 15 V 0085-0028

C17 trims the master clock; set it only with a frequency counter, to 3.579545 MHz ± 100 Hz at U10 pin 15.[3] Mattel's power supply flowchart also names C38 and C39, with the AC jack and fuse F1, on the path from the AC input to the power supply board; neither appears in the parts list, so read them from the board.[4][1]

Power supply board

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Mattel describes the board as a switching regulator: it rectifies the AC from the wall transformer and varies the duty cycle of a square wave to keep its outputs steady as the load changes. It also senses the ON/OFF/RESET button.[5] Its outputs and the control line are measured at the test points on its connector strip (see the table below).[4]

Mattel's Figure 6 drawing shows a large cylindrical part standing at the right-hand end of the board, two upright cylinders beside the heatsinked component, several smaller cylindrical parts towards the left and two wound parts at the front, beside the connector.[4] The drawing carries no reference designators or values. Treat it as a guide to where parts sit, and identify each one on the board itself.

Recording your board

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Before removing anything:

  1. Photograph both sides of the board.
  2. For each electrolytic, write down the reference designator printed on the board (if any), the capacitance, the voltage rating, the temperature rating and which side carries the negative stripe.
  3. Note the physical size, especially height, so the replacements fit under the console's top housing.
  4. Keep the record with the console.

Replace each part with the same capacitance and the same or a higher voltage rating. TP8 reads about +21 V DC with the console off, so part of the board runs at that voltage or more.[4] Never fit a replacement rated at or below the voltage you measure across the original's position.

Replacement procedure

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  1. Unplug the AC adapter and open the console as described in the maintenance guide.
  2. Remove the three Phillips screws that hold the power supply board to the standoffs on the logic board and lift it straight up off its 10-pin connector.[6]
  3. Record the board as above, then replace the capacitors one at a time, checking polarity against your notes for each.
  4. Refit the board, plug in a known-good adapter and check the test points below before running a game.

For C19 on the logic board, take the logic board out (four screws; lift it by the cartridge connector so the channel switch clears its opening) and observe its polarity on removal.[6]

Post-recap checks

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Power supply board test points (against TP3)
Test point Expected
TP1 to TP2 16–20 V AC
TP4 −2.10 to −2.40 V DC
TP5 +5.45 to +5.95 V DC
TP6 +11.5 to +12.5 V DC
TP7 +4.85 to +5.15 V DC
TP8 About +21 V DC off, +5 V DC on, 0 V with reset pressed

From Mattel's Figure 6 and troubleshooting flowchart. Press and release reset within 2 seconds before reading TP8 in the on state.[4]

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References

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  1. ↑ 1.0 1.1 1.2 1.3 Mattel Electronics, Service Manual, model 5872, parts list, pp. 21 and 23: logic board capacitors C1–C20, C30, C33, C35, C36; power supply board with parts, 5872-9539. File:Mattel Intellivision II Service Manual Model 5872.pdf.
  2. ↑ Mattel Electronics, Service Manual, model 5872, Figure 8, schematic diagram, p. 25 (PDF p. 26): C19 4.7 µF with R9 10 kΩ, CR3 and S1. File:Mattel Intellivision II Service Manual Model 5872.pdf.
  3. ↑ Mattel Electronics, Service Manual, model 5872, "Adjustments", p. 20: master clock adjustment with C17. File:Mattel Intellivision II Service Manual Model 5872.pdf.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Mattel Electronics, Service Manual, model 5872, troubleshooting flowchart, pp. 12–13 (including the check of the AC jack, C38, C39 and F1), and Figure 6, p. 19. File:Mattel Intellivision II Service Manual Model 5872.pdf.
  5. ↑ Mattel Electronics, Service Manual, Intellivision II model 5872, "System Description and Operation", pp. 5–6: switching regulator power supply board, senses the ON/OFF/RESET switch, 10-pin connection to the logic board. File:Mattel Intellivision II Service Manual Model 5872.pdf.
  6. ↑ 6.0 6.1 Mattel Electronics, Service Manual, model 5872, "Disassembly Procedure", p. 9. File:Mattel Intellivision II Service Manual Model 5872.pdf.


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