Search found 2303 matches

by 1024MAK
Wed May 22, 2019 10:40 am
Forum: Development
Topic: ZX Printer Belt
Replies: 130
Views: 21952

Re: ZX Printer Belt

Looking good :D :D :D

Mark
by 1024MAK
Thu May 16, 2019 5:35 pm
Forum: Hardware
Topic: ZX80 video improvements
Replies: 2
Views: 149

Re: ZX80 video improvements

ZX8-CCB can be used ;)
I upgraded the ZX80 that Richard owned. I put the ZX8-CCB in the modulator can as that was what was requested. But you don’t have to do that.

Chroma 80 interface (coming soon) according to Paul’s web site...

Mark
by 1024MAK
Mon May 13, 2019 3:42 pm
Forum: Hardware
Topic: White screen and no cursor at all
Replies: 17
Views: 463

Re: White screen and no cursor at all

The ceramic resonators are not polarity sensitive as such. However, there may be differences between the two sections of three terminal devices. It’s real intended purpose is as part of a filter circuit in television sets, hence it having three terminals. In the ZX81 circuit, one of the outside term...
by 1024MAK
Mon May 13, 2019 1:20 am
Forum: Hardware
Topic: White screen and no cursor at all
Replies: 17
Views: 463

Re: White screen and no cursor at all

I’ve got an issue 3 board (possibly produced for the French market given that it has a transistor inverting the video signal to the modulator) that has a resistor as mentioned in the posts above. Here are some photos of it: 85A05790-6F39-40AD-8FDE-A7DB1109A83B.jpeg 4CCD466D-D438-4461-B7A1-45F72059E2...
by 1024MAK
Sat May 11, 2019 7:14 pm
Forum: Sinclair Misc
Topic: CGC 2019
Replies: 2
Views: 130

Re: CGC 2019

by 1024MAK
Sat May 11, 2019 2:39 pm
Forum: Hardware
Topic: White screen and no cursor at all
Replies: 17
Views: 463

Re: White screen and no cursor at all

Test the Z80 /MREQ, /RFSH, /RESET, A14, A15 and A6 pins with your logic probe.

There is a pin out on the forum, check the link in my sig below.

Mark
by 1024MAK
Mon May 06, 2019 10:03 pm
Forum: Hardware
Topic: NOOO.. My just arrived TS 1500 is flakey!
Replies: 10
Views: 560

Re: NOOO.. My just arrived TS 1500 is flakey!

Good :D

Mark
by 1024MAK
Sat May 04, 2019 3:38 pm
Forum: Hardware
Topic: TS 1000 artifacts after warming up
Replies: 14
Views: 291

Re: TS 1000 artifacts after warming up

The Sinclair ULA uses a 6.5MHz ceramic resonator. Inside the ULA this frequency is divided by two to give the 3.25MHz CPU frequency. IIRC Andy’s replacement ULA module uses it’s own crystal and ignores the 6.5MHz ceramic resonator on the main board. Have you tried another monitor / TV ? The video ou...
by 1024MAK
Sat May 04, 2019 1:35 pm
Forum: Hardware
Topic: TS 1000 artifacts after warming up
Replies: 14
Views: 291

Re: TS 1000 artifacts after warming up

How much ripple is on the 9V PSU output and what voltage do you get?
Same question, but on the +5V rail.

Both can be tested on the pins of the 7805 voltage regulator, just be careful not to short anything out.

Mark
by 1024MAK
Fri May 03, 2019 3:20 pm
Forum: Hardware
Topic: Maplin ZX81 Voice PCB
Replies: 2
Views: 153

Re: Maplin ZX81 Voice PCB

This photo shows the Maplin expansion bus type card: https://www.sinclairzxworld.com/download/file.php?id=4333 These links should help: http://k1.spdns.de/Vintage/Sinclair/80/Peripherals/Maplin%20ZX81%20Talk-Back%20%28Kit%29/mvzx81.html https://www.sinclairzxworld.com/viewtopic.php?f=7&t=2493 Mark