Search found 26 matches

by Tiger
Sun Sep 06, 2020 2:46 am
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 11625

Re: ZX81 generates high pitched sound on CRT

I don't think that it is a software based fault. In my opinion modifying the ROM will not help. A reason can be the composite mod of the ZX81. There are so much possible ways to make the composite output. Maybe it is made with an capacitator it could be damaged - but then the noise must be heard in ...
by Tiger
Sat Sep 05, 2020 2:35 am
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 11625

Re: ZX81 generates high pitched sound on CRT

If the sound results from high-tension then it is not the location at the picture. But in the upper right corner at the tube-connector-PCB there is a solderpoint marked as C1 which I'm not sure that it looks damaged - if the wire isn't correctly soldered it may be the reason. At the monitor there mu...
by Tiger
Fri Sep 04, 2020 12:51 pm
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 11625

Re: ZX81 generates high pitched sound on CRT

@ dessony - thank you
@ mrtinb
maybe you can hear the sound with the ZX81 connected is that you get a mostly white screen. So the CRT needs a higher high tension level. I think you'll also hear this pitched sound with other equipment's that produce a bright video-signal.
by Tiger
Thu Sep 03, 2020 5:24 pm
Forum: Hardware
Topic: ZX81 generates high pitched sound on CRT
Replies: 28
Views: 11625

Re: ZX81 generates high pitched sound on CRT

@mrtinb vielleicht kannst Du ja deutsch verstehen, denn in englisch kann ich es leider nicht so ausdrücken: Bei Röhrengeräten (CRT) kommt im Hochspannungsteil ein Zeilentrafo zum Einsatz der eine Hochspannung zur Bildröhre erzeugt. Im laufe der Jahre ziehen diese Trafo's irgendwie Feuchtigkeit und d...
by Tiger
Tue Sep 01, 2020 3:51 pm
Forum: Welcome Area
Topic: Hello from Germany
Replies: 2
Views: 4629

Hello from Germany

Hello, nice Forum, so I'd decided to register here. My first contact with computers startet with a an Fairchild F8-Board in the 80s. The big step to program startet with an ZX81 which I bought as a kit-version. Mostly I transferred basic programs into machine language and shortened the routines to m...
by Tiger
Tue Sep 01, 2020 11:54 am
Forum: ZX Spectrum Lounge
Topic: Spectrum PCB and clones to sell
Replies: 0
Views: 9596

Spectrum PCB and clones to sell

Hello I'll sell my last repaired and build ZX parts:
https://www.ebay.de/sch/21gela/m.html?i ... 7675.l2562
if anyone is interested in it ...
Next time I'll offer the last spare parts (ULA for ZX81) I own for Sinclair computers