ZX Spectrum Schematics Errors & Fix.

[Muttley Black]

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.

[Guesser]

You might want to date and version your 'fixed' files in case there are still things to fix later.

[Muttley Black]

You might want to date and version your 'fixed' files in case there are still things to fix later.

Yes thats better, i edit my post

[1024MAK]

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

[zx64]

I found one more error in 3b.

ic24 pins 4 & 5 are swapped

[Ast A. Moore]

I found one more error in 3b.

ic24 pins 4 & 5 are swapped

Hey, you’re right! Thanks.