Search found 452 matches

by gozzo
Sun Oct 09, 2011 8:42 pm
Forum: FAQs
Topic: Monitor for ZX81
Replies: 6
Views: 25121

Re: Monitor for ZX81

I have a circuit idea for a simple add-on RF to composite converter unit so that no alterations would be needed to the insides of a ZX81 or any other home computer with RF TV output - will post details when (and if!) I get time to test it(if it works!).
by gozzo
Sun Oct 09, 2011 8:38 pm
Forum: FAQs
Topic: Monitor for ZX81
Replies: 6
Views: 25121

Re: Monitor for ZX81

The best thing to use with a ZX81 IS an old black-and-white portable(or big one) TV - that's what they were 'designed' to be used with - some ZX81's give a dark picture when used with colour TV's(back porch incorrect) - modern LCD things could be a bit hit or miss unfortunately unless you 'modify' t...
by gozzo
Sun Oct 02, 2011 10:15 pm
Forum: Software
Topic: Timex Sinclair TS 1500 vs. Sinclair Spectrum
Replies: 6
Views: 4670

Re: Timex Sinclair TS 1500 vs. Sinclair Spectrum

You'll need a TS2068, - as far as I understand it ,there was a ROM cartridge to make it more 'spectrum' compatible, but still not 100%, your best bet is to buy a proper spectrum somehow - you will also need a 50Hz capable TV.
by gozzo
Sat Aug 06, 2011 10:25 pm
Forum: Hardware
Topic: ZX81 Video problem
Replies: 10
Views: 7713

Re: ZX81 Video problem

Looking more carefully at the second of the 2 pictures above, it looks a bit like a tuning drift problem -the tell tale sign is the lighter 'ghosting' outline on the right of the characters - try manually 'fine tuning' your TV - if you can!, some modern TV's have no facility for this - if this 'cure...
by gozzo
Sat Aug 06, 2011 9:18 pm
Forum: Hardware
Topic: ZX81 Video problem
Replies: 10
Views: 7713

Re: ZX81 Video problem

You will need a can of 'freezer spray' - one at a time, squirt the middle of chips inside the zx81 (don't get it on the keyboard membrane tails, though, it will make them brittle and crack)- including the regulator - to see if it makes any difference - when it does, thats the dodgy chip! , if not , ...
by gozzo
Fri Aug 05, 2011 9:06 pm
Forum: Hardware
Topic: ZX81 Power supply specs
Replies: 17
Views: 18624

Re: ZX81 Power supply

Before trying your zx81 out for the first time I would advise carefully opening it up to see if the keyboard membrane 'tails' are ok, and then check if any of the chips are in sockets - if so, carefully remove each chip, squirt the chip pins and the sockets with a good contact cleaner which has a lu...
by gozzo
Fri Aug 05, 2011 8:56 pm
Forum: Hardware
Topic: ZX81 Power supply specs
Replies: 17
Views: 18624

Re: ZX81 Power supply

It should be possible to pick up a genuine zx81 psu eventually as they do turn up on various 'auction' sites now and again - just look for the 1.2 amp version not the older 700mA (0.7amp) version! Unfortunately I cant supply you with one as I only have one 1.2amp type ,and I am keeping it, otherwise...
by gozzo
Fri Aug 05, 2011 8:51 pm
Forum: Hardware
Topic: ZX81 Power supply specs
Replies: 17
Views: 18624

Re: ZX81 Power supply

No, thats just the MAXIMUM amount of current you can draw from this PSU. The zx81 uses quite a bit less than this, just don't use a power supply with a current rating LESS than 1.2amp, especially if using the ZX printer or some other add-ons as it will overheat that PSU.
by gozzo
Fri Aug 05, 2011 8:41 pm
Forum: Hardware
Topic: ZX81 Power supply specs
Replies: 17
Views: 18624

Re: ZX81 Power supply

The lower one - which shows the positive (+) going to the 'dot' in the diagram. Although I said some add-ons need a bit more than 9v, do NOT be tempted to try the 12v setting as it is as this will probably cause the zx81 regulator to overheat, and maybe kill your add-ons, unless you wire in 1 or 2 3...
by gozzo
Fri Aug 05, 2011 7:34 pm
Forum: Hardware
Topic: ZX81 Power supply specs
Replies: 17
Views: 18624

Re: ZX81 Power supply

Set it for 9v with a positive 'pin' /'centre' polarity and it will probably be ok, - but - if using some 16k rampacks(cheetah, viscount, not sure about the sinclair ones, maybe some others), they may need a slightly higher voltage - about 10 to 11v - to work (the zx81 psu actually produces a bit mor...