Search found 658 matches

by Lardo Boffin
Mon Dec 11, 2017 4:29 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2473

Re: ZX81 rebuild

gammaray wrote:
Mon Dec 11, 2017 3:27 pm
Is there a ZTX313 at TR1 position too? I would use a ZTX313 on both TR1 & TR2.

As Wilf wrote me once "...check the pin out...(again)"

Good luck!
Also wise words!
by Lardo Boffin
Mon Dec 11, 2017 4:28 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2473

Re: ZX81 rebuild

sirmorris wrote:
Mon Dec 11, 2017 10:21 am
Rule the third:
'there's always one more'
Wise words!
by Lardo Boffin
Mon Dec 11, 2017 9:21 am
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2473

Re: ZX81 rebuild

Found some very small solder strands (after much holding the board up to the light at odd angles to see if anything glinted) and removed them. No difference. :evil:
by Lardo Boffin
Sun Dec 10, 2017 9:53 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2473

Re: ZX81 rebuild

Don't Panic is a phrase on the cover of The Hitchhiker's Guide to the Galaxy... Hence is the standard response to any situation... :lol: Mark Clearly I forgot my towel. Available here and here apparently ;) <Galactic trading rules dictate that Earthlings must trade at their own risk> Have you got a...
by Lardo Boffin
Sat Dec 09, 2017 8:15 am
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2473

Re: ZX81 rebuild

1024MAK wrote:
Fri Dec 08, 2017 11:54 pm
Don't Panic is a phrase on the cover of The Hitchhiker's Guide to the Galaxy...
Hence is the standard response to any situation... :lol:

Mark
Clearly I forgot my towel.
by Lardo Boffin
Fri Dec 08, 2017 1:44 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2473

Re: ZX81 rebuild

Don't Panic! Just start your fault finding investigation from the start... Test the +5V power rails Check for solder splashes using your eye (and maybe a magnifying glass) Test the Z80 CPU pins, A14, A15 plus /RESET, /MREQ etc... You'll get there in the end ;) Mark Its more stress than panic. This ...
by Lardo Boffin
Fri Dec 08, 2017 9:26 am
Forum: Hardware
Topic: Improving Timex/Sinclair Tape Loading
Replies: 60
Views: 2030

Re: Improving Timex/Sinclair Tape Loading

Excellent! Having had some experience of fixing tracks I have broken ( :oops: ) I suspect it will be no problem to sort. 8-)
by Lardo Boffin
Thu Dec 07, 2017 2:40 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2473

Re: ZX81 rebuild

Did you change resistor values? No - I left the original resistor in and removed the test ones. The only thing I can think of is that I shorted something while soldering but cannot see anything. I’m getting the same pulse on pin 6 of the Z80 on this board as another working one so it looks like tha...
by Lardo Boffin
Thu Dec 07, 2017 1:18 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2473

Re: ZX81 rebuild

Arrggghhhh! The ZTX313s arrived today so I put them in (the right way round 8-) ), got a pulse and switched on. I get a white screen and no K. Did I say argh? :evil: The board was working - when I temporarily put the original TR2 back in earlier in the week I got a K. So I guess the question is - wh...
by Lardo Boffin
Wed Dec 06, 2017 4:54 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2473

Re: ZX81 rebuild

Paul wrote:
Wed Dec 06, 2017 4:53 pm
Lardo Boffin wrote:
Wed Dec 06, 2017 4:16 pm
Well, so long as they are polite! :D
I hope I wasn't unpolite.
No - you were very polite!