Search found 225 matches

by Erm
Sun Dec 29, 2019 2:22 pm
Forum: Hardware
Topic: ZX80 troubleshooting with oscilloscope.
Replies: 11
Views: 4280

Re: ZX80 troubleshooting with oscilloscope.

Good idea. But it is proving quite tricky! I shall persevere.
by Erm
Sat Dec 28, 2019 10:08 pm
Forum: Hardware
Topic: ZX80 troubleshooting with oscilloscope.
Replies: 11
Views: 4280

Re: ZX80 troubleshooting with oscilloscope.

Everything on the Z80 and the RAM looks the same as the known good ZX80, as far as I can tell.
by Erm
Sat Dec 28, 2019 9:27 pm
Forum: Hardware
Topic: ZX80 troubleshooting with oscilloscope.
Replies: 11
Views: 4280

Re: ZX80 troubleshooting with oscilloscope.

Ignore the above. One was set to AC, the other DC!
by Erm
Sat Dec 28, 2019 8:11 pm
Forum: Hardware
Topic: ZX80 troubleshooting with oscilloscope.
Replies: 11
Views: 4280

Re: ZX80 troubleshooting with oscilloscope.

Edit: IGNORE this post, I noticed one probe was set to AC and the other DC! Ok, I think there is activity where there should be and highs where they should be. I compared the dodgy new ZX80 to my known good original. Here is a pic showing the read out for pin 16 on the Z80. Yellow is the good one, ...
by Erm
Sat Dec 28, 2019 5:04 pm
Forum: Hardware
Topic: ZX80 troubleshooting with oscilloscope.
Replies: 11
Views: 4280

Re: ZX80 troubleshooting with oscilloscope.

Thanks so much Mark. I will check those things in due course. I did also try with a known good 16k RAM pack and there was no change. The RAM chips I got with the board are: MM2114N-2L and MM2114-3. Interesting about them having to be different, as I changed them for 2 from a ZX81 (because I knew bot...
by Erm
Sat Dec 28, 2019 4:01 pm
Forum: Hardware
Topic: ZX80 troubleshooting with oscilloscope.
Replies: 11
Views: 4280

ZX80 troubleshooting with oscilloscope.

Hello. I got an oscilloscope for Christmas! I won't pretend I know how to use it. I thought I could use it to find out why my ZX80 Russian clone isn't behaving properly. Problem: there is no K cursor. When I power it on it flickers with a brief black horizontal line (which appears normal), goes comp...
by Erm
Thu Dec 26, 2019 11:15 am
Forum: Hardware
Topic: I got a ZX80!
Replies: 10
Views: 3320

Re: I got a ZX80!

Don't know if Grant Searle's ZX80 page is of any help. He shows how to modify the setup in order to use a different EPROM. I think it also has links to the ROM images. http://searle.wales/ Kind regards Andy Thanks, yes, I've read up on everything and know it's fairly easy, but for the sake of origi...
by Erm
Thu Dec 19, 2019 9:00 pm
Forum: Hardware
Topic: "Different" ZX81's
Replies: 201
Views: 73860

Re: "Different" ZX81's

And then there are the manuals. https://www.sinclairzxworld.com/viewtopic.php?f=14&t=2903&hilit=Different+manuals&start=10#p31076 Must have a look through mine at some point... Yes, and the first edition version is actually a little wider and takes up all of the width in the poly base. And of cours...
by Erm
Thu Dec 19, 2019 6:38 pm
Forum: Hardware
Topic: "Different" ZX81's
Replies: 201
Views: 73860

Re: "Different" ZX81's

I noticed something so anorak today that it is (almost) embarrassing!

There are different polystyrene packaging parts, with slight mould differences to both halves.
by Erm
Sun Dec 15, 2019 9:19 pm
Forum: Development
Topic: New ZX80 cases
Replies: 28
Views: 26729

Re: New ZX80 cases

The 4 versions are quite simple, its the hole for the antenna connector, looking from the rear, the UK etc the hole is nearest the power socket on the left, the USA version its next to the edge connector on the right. Most clones its dead centre and there will be a version available with no hole at...