what goes wrong when you swap the ula position ??

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jojo
Posts: 129
Joined: Mon Mar 16, 2020 5:25 pm

what goes wrong when you swap the ula position ??

Post by jojo »

one of the problem speccies on my workbench has a "strange" problem ,
i don't know how many specialists tried to repair it , but their traces are everywere.
m_IMG_3068.jpg
and the socket too.
m_IMG_3069.jpg

Now of course i wonder what can i expect to be defective after discovering this ( and no rotating it does NOT solve any problem ) .



jojo
Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system-Currah microspeech -Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 floppy- Minerva - Qimi-and much more .
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1024MAK
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Re: what goes wrong when you swap the ula position ??

Post by 1024MAK »

The actual manufacturers that populated the PCBs for Sinclair were not too bothered about getting the IC sockets the correct way round :?

Normally if you put a chip in the wrong way round, it normally dies very quickly. It is possible, due to the design of a ULA chips, that it may have survived.

Mark
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jojo
Posts: 129
Joined: Mon Mar 16, 2020 5:25 pm

Re: what goes wrong when you swap the ula position ??

Post by jojo »

so i gave her a new ula , and the result now looks like this ;
m_18-7-2022 19-42-34.jpg

so i can say that something is working now , albeit with heaps of other problems .
Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system-Currah microspeech -Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 floppy- Minerva - Qimi-and much more .
bola_dor
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Re: what goes wrong when you swap the ula position ??

Post by bola_dor »

Not long ago I saw this...
I just put it back in the right way and all worked fine...
IMG-20220707-WA0000.jpg
Ernesto
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come :D
jojo
Posts: 129
Joined: Mon Mar 16, 2020 5:25 pm

Re: what goes wrong when you swap the ula position ??

Post by jojo »

unfortunately my project shows the image above ( after being fully dead , so ula was surely killed )

now to find the solution to get it fully working again
Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system-Currah microspeech -Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 floppy- Minerva - Qimi-and much more .
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