I check ULA (OK),Z-80 (OK) ,ROM (OK) y TR6 (OK). It hung / reset when It loaded games and also with some external interfaces. Some tests working well but the spectrum didn't work properly. Spectrum run very well.Īfter TR4 changing (there weren't -5v & +12v), the spectrum started well. Finally I discover that all electrolytic capacitors near of 7805 (C27,C46) fail when 7805 warm up. C44 is changed because is some ripple in +12VA of LM1889. Interference: Checked all electrolytic capacitors. Yellow colour: Adjusts white colour playing potentiometers VR1 and VR2.įalse contacts: Change power connector with a new one. TR4 burns during testing because this problem. Power connector doesn't make good contact and fails. It also shows a lot of interferences when spectrum warm up (ULA and 7805 warm up a lot in this spectrum model). Spectrum works but the screen is too yellow. The screen showed a lot of colour pixel (there weren't anyone flash pixel). Upper memory fault.Changed a 4532 chip (32Kx1) to new 4164 (64Kx1). It start, clear the screen but it hang and show white border and black paper. Changed IC10, 4116 chip with a new one.Īt start, the screen showed a white border, cyan paper and a tiny black line of pixel The message "1982 sinclair research" was corrupted. It started with normal screen but it had some cyan pixels. Showed RAM fault at chip two (see photo) but the ram chips were fine. Ql started with white screen (normally it was ram fault). This clon only have one RAM bank made by 4164 chip.Changed two chips. It started with a black screen with some vertical lines.Touching RAM chips, the screen changes and showed a lot of colour blocks. Spectrum didn't show divIDE screen and also NMI button didn't work.
Spectrum started like divIDE was not connected. Repair a Z-80, memory, transistor fault, etc, etc.
Today, It's not posible to repair a ULA fault but it's posible to I also repair some Spectrum that people gave me to see why they didn't
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