Search found 41 matches
- Thu Aug 12, 2021 3:45 pm
- Forum: Hardware
- Topic: VLa81 noisy video signal
- Replies: 19
- Views: 4112
Re: VLa81 noisy video signal
Change the capacitor C2 (located close to the modulator) into a bigger one, 100nF or 1µF.
- Tue Aug 10, 2021 6:31 pm
- Forum: Hardware
- Topic: VLa81 noisy video signal
- Replies: 19
- Views: 4112
Re: VLa81 noisy video signal
Check the Ground Line. Do you have noise between the ground at the modulator and the ground at the 7805 regulator (heat sink)?
- Fri Jun 25, 2021 3:20 pm
- Forum: Hardware
- Topic: ZX81 Troubleshooting
- Replies: 13
- Views: 5164
Re: ZX81 Troubleshooting
Check also the signal at CPU/18(=HALT) and ULA/17(=HALT) as well as the signals around TR1.
- Thu Jun 24, 2021 5:07 pm
- Forum: Hardware
- Topic: ZX81 Troubleshooting
- Replies: 13
- Views: 5164
Re: ZX81 Troubleshooting
Try a different CPU or look for shorts around pin17. (I use a Andy Rea's ULA).
- Fri Apr 02, 2021 10:55 am
- Forum: Hardware
- Topic: Power consumption and the voltage regulator
- Replies: 6
- Views: 2275
Re: Power consumption and the voltage regulator
Hi patters,
look for Step Down regulators at e Ba* as an alternative.
look for Step Down regulators at e Ba* as an alternative.
- Thu Apr 01, 2021 11:12 pm
- Forum: Hardware
- Topic: Power consumption and the voltage regulator
- Replies: 6
- Views: 2275
Re: Power consumption and the voltage regulator
Hello patters, we've detected the same problem in https://forum.tlienhard.com/phpBB3/viewtopic.php?p=49046#p49046 . The internal regulator will be overheated. A switching regulator is strongly recommended to overcome this problem. I usually use cheap Chinese step down regulators as shown in the pict...
- Sun Mar 21, 2021 4:55 pm
- Forum: Software
- Topic: Pascal for ZX81
- Replies: 71
- Views: 20548
Re: Pascal for ZX81
It seems there is no direct way to write a program, to compile it afterwards and run immediately. You have to save in between. Is this true or am I wrong?
- Sun Mar 07, 2021 12:30 pm
- Forum: GAMES
- Topic: New ZX81 Games
- Replies: 363
- Views: 682054
Re: New ZX81 Games
@DrBeep: Thank you for assisitance, with WRX on EO it runs perfectly. Also on my ZX81NU, even with WESPI+Display. My score is 85
- Sat Mar 06, 2021 12:29 pm
- Forum: GAMES
- Topic: New ZX81 Games
- Replies: 363
- Views: 682054
- Fri Jan 29, 2021 11:54 pm
- Forum: Hardware
- Topic: ZX-81 Power supply question (USA)
- Replies: 3
- Views: 1252
Re: ZX-81 Power supply question (USA)
Don't worry, this PSU can be used. If there is no load then the voltage goes up by the factor sqrt(2)=1.41. So, 9.75V * 1.41 = 13.7V is near to your measured value. And since it is original, there is also no problem with the polarity.