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zx 48k no graphics

Posted: Tue Sep 26, 2023 1:47 pm
by swalker
So I finally got my dodgy 48k from the bay of thieves and it was described as above, but was overall dodgy, one of the ribbon s broke on opening and the other was bent! The neutral wire was also loose in the plug, but neither if these fixed the issue. Thanks to @1024MAK I followed his advice in another post and found that the -5V is not there so I have a ZTX 650 on order.
Also the 80s display I mentioned in my hello post is now taking shape.
Image

Re: zx 48k no graphics

Posted: Tue Sep 26, 2023 2:28 pm
by 1024MAK
Hopefully just replacing the transistor will get the display back to normal, but don’t be surprised if one or more of the ‘lower’ DRAM chips have failed (or been killed). By the way, the ZTX650 is obsolete, but the higher voltage parts, the ZTX651 or the ZTX653 (both still in production) are suitable replacements.

Mark

Re: zx 48k no graphics

Posted: Wed Sep 27, 2023 9:08 pm
by swalker
Its alive... ish
I get the boot screen but only half the keyboard works.
Bottom 2 rows right hand side out.
I will do a bit of keyboard mashing ( on a workign computer ) to see if the problem is addressed else where. If not ill start a new post.
Thanks for reading
And replying of course Mark.

Re: zx 48k no graphics

Posted: Thu Sep 28, 2023 8:04 pm
by swalker
Fixed, i did mention somewhere the ribbon was in bad nick, quick trim and i have a fully functional keyboard again.
Let the fun begin...

Re: zx 48k no graphics

Posted: Fri Sep 29, 2023 6:51 am
by hellraiseruk
Another one lives again! Good work 👏

JD

Re: zx 48k no graphics

Posted: Sat Sep 30, 2023 4:26 pm
by 1024MAK
@swalker

Well done on bringing it back to life :D :dance

Mark