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ZX Spectrum +3 (Issue 1) Sound Fix *updated*

August 22nd, 2009 Leave a comment Go to comments

Sound fix diagram here. (pdf)

from Cristian Secară Homepage:

The first release (the +3) has a fatal hardware mistake: the 128K sound output is completely distorted.

  • Tech explanation: the analog output of the AY-3-8912 sound chip was intended to be amplified by a one stage common-emitter transistor. In practice, they have forgot to put a resistor to the transistor’s emitter. The result: the transistor works in switch-mode – the sound is converted from analog multi-level amplitude to digitized two-level amplitude, same as the old 48K sound system.

source: secarica.ro ay8912 Demos

Categories: Gallery, Projects / Repairs, Retro Computers and other stuff..., Sinclair family, Today, Various
  1. Tachbach
    November 24th, 2011 at 05:45 | #1
    Reply | Quote

    As I can solve this problem in the issue 2 Spectrum +2a ???? this sounds like a guitar through a BOSS OVERDRIVE

    thanks friend.

  2. Tachbach
    November 24th, 2011 at 05:48 | #2
    Reply | Quote

    how can i solve this problem in the issue 2 Spectrum +2a ???? this sounds like a guitar through a BOSS OVERDRIVE

    thanks friend.

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