Retro Revival

 

ZX Spectrum Bits & Bobs Bytes

Maintenance and Repair : Capacitor Replacement


Capacitor List and Notes Layout diagrams


Capacitor List and Notes

16/48K Rubber Key and Plus models

Below is a list of the standard capacitors required for a 16K/48K Spectrum, along with the Vishay part numbers. Vishay's are high quality, will last for many years, and come in a blue package that therefore reflects the originals as close as possible.

  • 3 x 1uf 63v (Vishay: MAL203038108E3) [2 x on Issue 2, 4A and 4S motherboards]
  • 1 x 4.7uf 63v (Vishay: MAL203038478E3)
  • 6 x 22uf 25v (Vishay: MAL203036229E3) [7 x on Issue 4B and 4S motherboards]
  • 2 x 100uf 25v (Vishay: MAL202136101E3 )
16/48K Capacitor Kit at Retro Revival Shop
16/48K Refurb Kit at Retro Revival Shop

The voltage ratings may be higher than the originals in some cases, but this is the maximum voltage that can be safely applied to the capactior and the Spectrum works well below these voltages and hence will be fine (and safe!). The important rating is the capacitance which must be correct.

Capacitors are polarised and you MUST install them the correct way around. The positive end is marked on the circuit board with a + symbol in most cases, with one exception on the Issue 2 board (see below). There are also a couple of service mods for Issue 2 and 3 motherboards that may or may not have been performed. The DC-DC mod on Issue 3 boards also appears in slightly different places. Therefore you may find some differences from 'standard' or between 2 boards of the same issue.

Issue 2 boards:

  • C46 has a printing error on the board and it is marked incorrectly with the positive on the right. The capacitor should be mounted with the positive on the left.
  • C27 and C47 are often replaced by a higher rated 105 deg C capacitor due to the heat they are subjected to by proximity to the heatsink.
  • C65 may be ceramic type with no polarity marked and should be replaced with a 22uf capacitor with the +ve on the right.
  • The DC-DC mod may exist, with a 4.7uf capacitor fitted with +ve lead connected to the top lead of c34 and negative to the left lead of R58. R60 will also have had the 100 Ohm resistor replaced with a 270 Ohm.
Issue 3 boards:

The service mod for the DC-DC circuit will probably have been done.
  • C47 should be removed
  • Diode D19 is replaced with a 1uf capacitor (C79) with the +ve lead to the right.
  • Two BA157 diodes will have been added, although the actual location varies it is often just below the keyboard membrane connector KB2 on the right hand side. A new 22uf capacitor (C78) is added with the -ve lead connected to the junction of the 2 new diodes.

 

128K 'Toastrack' UK model

  • 3 x 1uf 63v
  • 1 x 4.7uf 63v
  • 4 x 22uf 25v
  • 3 x 47uf 25v
  • 3 x 100uf 25v
128K 'Toastrack' UK Capacitor Kit at Retro Revival Shop
128K 'Toastrack' UK Refurb Kit at Retro Revival Shop

 

Plus 2 and Plus 3 models

NOTE in some cases people find that the installed capacitor has a larger voltage value than the above listing. It is believed that this is as Sinclair were struggling/as Amstrad took over, in order to cut costs they used whatever stock was available in the factory. The values listed/supplied are the correct official Sinclair values and your machine will not be harmed by installing these lower values.

128K +2 'Grey' Iss 3 model

  • 4 x 1uf 50v
  • 1 x 4.7uf 16v
  • 1 x 10uf 25v
  • 5 x 22uf 16v
  • 2 x 47uf 16v
  • 2 x 100uf 16v
  • 2 x 220uf 16v
128K +2 'Grey' Iss 3 (Incl. Tape m'board) Capacitor Kit at Retro Revival Shop

128K +2A 'Black' model

  • 2 x 1uf 50v
  • 2 x 1uf 100v
  • 3 x 100uf 25v
128K +2A 'Black' (Incl. Tape m'board) Capacitor Kit at Retro Revival Shop

128K +3 (Disk) model

  • 4 x 1uf 100v
  • 3 x 100uf 25v
128K +2A 'Black' (Incl. Tape m'board) Capacitor Kit at Retro Revival Shop

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Layout diagrams

All layouts in a single PDF

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