There is an error on issue 3b schematic. ULA pin "27" is for sure the pin "37", like you see it on issue 2 schematic.
Here is the issue 3B Schematic with no error after an edit:
I mark every fixed Schematic with (-update-&date) at the end. In this case:
Original schematic with error: ZXSpectrumIssue3b-Schematics.gif
Updated schematic: ZXSpectrumIssue3b-Schematics-update-10-5-2019.gif
You can post here the errors you find in any issues, so we can fix it and have them correctly on this thread.
ZX Spectrum Schematics Errors & Fix.
- Muttley Black
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ZX Spectrum Schematics Errors & Fix.
Last edited by Muttley Black on Fri May 10, 2019 1:24 pm, edited 3 times in total.
Re: ZX Spectrum Schematics Errors & Fix.
You might want to date and version your 'fixed' files in case there are still things to fix later.
- Muttley Black
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Re: ZX Spectrum Schematics Errors & Fix.
Issue 3 to Issue 4B
https://www.worldofspectrum.org/forums/ ... ion/32717/
https://www.worldofspectrum.org/forums/ ... ent_857794
Note that the issue 1 and 2 boards did not use a transistor to drive the speaker. To increase the speaker volume, TR7 was added. It's collector connects to the +9V rail, and not the +5V as shown in most of the schematics.
Issue 3, 3B
https://www.worldofspectrum.org/forums/ ... ent_855560
Issue 4B
https://www.worldofspectrum.org/forums/ ... ent_781641
I know there are more, but these are just as a result of a quick search on WoSf.
Mark
https://www.worldofspectrum.org/forums/ ... ion/32717/
https://www.worldofspectrum.org/forums/ ... ent_857794
Note that the issue 1 and 2 boards did not use a transistor to drive the speaker. To increase the speaker volume, TR7 was added. It's collector connects to the +9V rail, and not the +5V as shown in most of the schematics.
Issue 3, 3B
https://www.worldofspectrum.org/forums/ ... ent_855560
Issue 4B
https://www.worldofspectrum.org/forums/ ... ent_781641
I know there are more, but these are just as a result of a quick search on WoSf.
Mark
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“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: ZX Spectrum Schematics Errors & Fix.
I found one more error in 3b.
ic24 pins 4 & 5 are swapped
ic24 pins 4 & 5 are swapped
- Ast A. Moore
- Rick Dangerous
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Re: ZX Spectrum Schematics Errors & Fix.
Hey, you’re right! Thanks.
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.