Wanted - ZX81 Issue 3 board.

ZX80 / ZX81 hardware and software requested for either sale or swapping
Post Reply
User avatar
Andy Rea
Posts: 1606
Joined: Fri May 09, 2008 2:48 pm
Location: Planet Earth
Contact:

Wanted - ZX81 Issue 3 board.

Post by Andy Rea »

Hi,

I'm after an issue 3 board in any condition with or without case

Thanks Andy
what's that Smell.... smells like fresh flux and solder fumes...
sirmorris
Posts: 2811
Joined: Thu May 08, 2008 5:45 pm

Re: Wanted - ZX81 Issue 3 board.

Post by sirmorris »

I'm pretty sure I can sort you out Andy.

I'll check tonight. Any particular colour, sir? :lol:
Moggy
Posts: 3231
Joined: Wed Jun 18, 2008 2:00 pm

Re: Wanted - ZX81 Issue 3 board.

Post by Moggy »

sirmorris wrote:I'm pretty sure I can sort you out Andy.

I'll check tonight. Any particular colour, sir? :lol:
Careful Charlie not all issue 3s were red early ones were still green :lol:
User avatar
Andy Rea
Posts: 1606
Joined: Fri May 09, 2008 2:48 pm
Location: Planet Earth
Contact:

Re: Wanted - ZX81 Issue 3 board.

Post by Andy Rea »

Doh now i kearn that there where 2 different colours !

@SirMorris, no any colour will do, just decided it's about time i extended my collection of Zeddies and what better way than to get a issue 3 board, since as all mine are issue 1's

Regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
User avatar
Andy Rea
Posts: 1606
Joined: Fri May 09, 2008 2:48 pm
Location: Planet Earth
Contact:

Re: Wanted - ZX81 Issue 3 board.

Post by Andy Rea »

I now have a question for owners of issue 3 boards.

does any of your boards have an extra resistor solder from the right side of C6 (above the CPU) ?

Thanks Andy
what's that Smell.... smells like fresh flux and solder fumes...
olpo01
Posts: 3
Joined: Wed Nov 17, 2010 7:19 am

Re: Wanted - ZX81 Issue 3 board.

Post by olpo01 »

Yes my issue3 zx81 have that resistor.
User avatar
PokeMon
Posts: 2264
Joined: Sat Sep 17, 2011 6:48 pm

Re: Wanted - ZX81 Issue 3 board.

Post by PokeMon »

Me too. It's 1k resistor connecting C6 / X1 (quarz oscillator) to ground.
User avatar
Andy Rea
Posts: 1606
Joined: Fri May 09, 2008 2:48 pm
Location: Planet Earth
Contact:

Re: Wanted - ZX81 Issue 3 board.

Post by Andy Rea »

PokeMon wrote:Me too. It's 1k resistor connecting C6 / X1 (quarz oscillator) to ground.
Quartz or ceramic resonator ?

reason i ask it the oscillator circuit i am using in the Replacment ULA did not work until i disconnected this ' extra ' resitor, Which is not present on the issue 1 boards.

I shal have a tinker with the circiut and see if it can be altered to work with both.

Andy
what's that Smell.... smells like fresh flux and solder fumes...
User avatar
PokeMon
Posts: 2264
Joined: Sat Sep 17, 2011 6:48 pm

Re: Wanted - ZX81 Issue 3 board.

Post by PokeMon »

ceramic resonator ...

You can place a resonator on your "ULA replacement board" I think and forget the resonator on the issue one or issue 3 board ...
It's not used for something else, so why not build the oscillator on your ULA ? ;)
The ULA is the boss of the clock ...
Post Reply