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Spare parts for Commodore 64, ZX Spectrum and more!

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ZX Spectrum Transistors

Some of the transistors originally used in the Spectrum are now obsolete - listed below are some suitable replacements.

Products:

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BC184 Transistor

TR8 and TR9 on Spectrum 16/48K issue 3 to 6 boards
Brand new

BC549C Transistor

A general purpose NPN transistor that can be used to make an alternative version of composite video mod on the Spectrum. Using a transistor instead of a simple wire or capacitor provides a stronger signal, usually giving a brighter picture. It also buffers the Spectrum's video circuitry so much of the load is taken by this transistor. However, it may not be compatible with modern LCD TVs.

Transistor video mod connections:

Collector (left lead in image) to 5V pad (TV modulator power, disconnect the TV modulator power wire)
Base (centre lead) to Spectrum video out pad (disconnect the TV modulator signal wire)
Emitter (right lead) to video socket - it's best to use a small piece of wire to extend this lead.

Note: Alternatively, two BC549s can be used to replace TR1 and TR2 to give a brighter picture when the composite mod is done uisng a capacitor (though they must be fitted rotated 180' compared to the silk screen legend). Please see this article for details.

Brand new

MPS2369 Transistor

A cheaper replacement for the obsolete ZTX313 (has same pin-out / case orientation and approx same spec)

Notes:

Should be oriented as per the silk screen printing on the PCB.
As the MPS2369 has a slightly higher gain, if used at TR1/TR2 it can increase the picture brightness slightly - this may create white flaring in the standard RF video output (but this not an issue if the Spectrum is composite modded) . If in doubt, use ZTX313 at TR1/TR2.
New, old stock

ZTX313 Transistor

Often found in the Spectrum 16/48 at TR1, TR2, TR3 and TR6 locations.
Also used in the ZX81
New, old stock

ZTX450 Transistor

For TR7 (speaker driver in Issue 3 and above boards)
Brand new

ZTX650 Transistor

Found at TR4 in the 16/48K Spectrums
New, old stock

ZTX651 Transistor

Replaces ZTX650 (TR4)
Can replace C2236A on revision 4S boards, but you must use the alternative pads provided to the right of the C2236A and fit the ZTX651 with the flat side on the left.

ZTX751 Transistor

Replaces ZTX213 in TR5 position (and A733 on 4S boards)
Brand new