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Sinclair Spectrum Break – Recovering & Repair *updated*

Sinclair Spectrum Break - Recovering & Repair

This gallery shows some stages of the repair of the Sinclair Spectrum 48k.

Defects found on the Sinclair Spectrum #1:

  • Black Screen of Death/Garbage Screen.

Components replaced:

  • 8 x 4116 RAM
  • 1 x Z80 CPU
  • Extra:
    • Composite Video

Defects found on the Sinclair Spectrum #2:

  • There are no colors.

Components replaced:

  • 5 x Electrolytic Capacitors 22uf / 16v
  • 1 x SN94459 (LM 1889) Tv video Modulator IC with Chroma Reference Signal (Color)

Defects found on the Sinclair Spectrum #3:

  • Jaundice problems.

Calibration:

  • Calibration of Trimmer (VR2)

Defects found on the Sinclair Spectrum #4:

  • Black Screen of Death.

Components replaced:

  • 1 x RAM TMS4532
  • 1 x Transistor ZTX650
  • Extra:
    • Composite Video
    • Conversion from Spectrum (Issue 2) To Spectrum +

Defects found on the Sinclair Spectrum #5:

  • Garbage Screen and high absorption on the 12v line and 0v (ground) with explosion of the transistors ZTX-650 (651) and ZTX-213

Components replaced:

  • 1 x Zener 5v1
  • 12 x Electrolytic capacitors
  • 3 x 4116 RAM (two of these in total short circuit between pin 8 and 16)
  • 8 x OKI 3732 RAM
  • 1 x Sinclair ROM
  • 1 x 74HCT(LS)32
  • 1 x Transistor ZTX-213
  • 1 x Transistor ZTX-650
  • Extra:
    • Composite Video
  • Info:
    • About the explosion of the transistors i have isolated the problem, are the ram (LOW).

      The bad way used some years ago was cut the pin 8 of the all 4116 ram to isolate the bad one, in this case, i didn’t cut the pins of the ram, but i have cut the track of 12v which is part of all the 4116 ram, doing so, the transistor ZTX650(651) doesn’t explode.

      At this point there is a short in one or more RAM between +12 and 0v. I have measured the absorption where i have cut the track and it absorbs too much.

      I just have to unsolder the pin 8 of the 4116 ram and trying to isolate it for find which ram is short-circuited.

  • …it was not over:
    • When the repair is finished and i have replaced all OKI 3732 RAM with a new one, another IC has decided to die, a 74HC(LS)32. I have no words.

Defects found on the Sinclair Spectrum #6:

  • Faulty / AutoLoad.

Components replaced:

  • 1 x TMS 4532 RAM
  • Extra:
    • Composite Video

Sinclair Spectrum Faulty / AutoLoad Video:

  1. Emiliano
    November 4th, 2018 at 08:13 | #1

    Ciao, ho uno ZX Spectrum 48k issue 3, con modifica composito, ma lo schermo è sempre nero, è possibile ripararlo?

    grazie

    Emiliano

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