Greetings and thank you very much.
Does not boot and red screen
Does not boot and red screen
A friend has given me a spectrum zx, but it does not start, on the television I can see the following image. I've oponed it and everything seems fine. I've read it may be low memory, but I'm not sure, and before changing it I want to make sure. Does anyone know what could cause the problem?
Greetings and thank you very much.
Greetings and thank you very much.
Re: Does not boot and red screen
Yes it seems, that it is a memory fault. Mostly Lower-RAM faults offer a scrambled screen, but there are a lot of variations. Upper RAM or a faulty ROM mostly displays a constant paper (mostly black) but in your case there is something in the lower right paper so it is one (or more) of the Lower RAM's. But first check the voltages -5V and 12V at the 4116's ...
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Ast A. Moore
- Rick Dangerous
- Posts: 2644
- Joined: Mon Nov 13, 2017 3:16 pm
Re: Does not boot and red screen
If the border is consistently white across reboots, then the CPU can execute some ROM code. So, the fault is likely with the RAM.
Every man should plant a tree, build a house, and write a ZX Spectrum game.
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Re: Does not boot and red screen
Thank you very much, first I will check voltage and if it is ok change 4116 chips.
Thank you.
Thank you.
Re: Does not boot and red screen
Before you start desoldering RAM chips use a diagnostic card, like Retroleum's Smart Card or a Dandanator, if you have one available. They might be able to point you to the culprit(s)!
Re: Does not boot and red screen
All good advice.
Checking for faults that prevent a ZX Spectrum booting is fairly straightforward for the first few steps.
* Check the voltages, both incoming and the generated -5 and 12v rails.
* Use a diagnostics card to check the lower ram ( if possible ).
* Confirm the ULA is working correctly.
It's usually after that, you can start the repairs. You may need to remove the lower RAM also if it stops you getting the voltage rails working again, as it's often the failure of the lower RAM that leads to the power rails failing.
Checking for faults that prevent a ZX Spectrum booting is fairly straightforward for the first few steps.
* Check the voltages, both incoming and the generated -5 and 12v rails.
* Use a diagnostics card to check the lower ram ( if possible ).
* Confirm the ULA is working correctly.
It's usually after that, you can start the repairs. You may need to remove the lower RAM also if it stops you getting the voltage rails working again, as it's often the failure of the lower RAM that leads to the power rails failing.
Re: Does not boot and red screen
Fixing ZX Spectrums in the 21st Century
https://github.com/brendanalford/zx-diagnostics
https://github.com/brendanalford/zx-diagnostics