MZ-80K displaying garbage chars on screen

S_U_C
Posts: 69
Joined: Sun Feb 17, 2019 6:41 pm

Re: MZ-80K displaying garbage chars on screen

Post by S_U_C »

You reported that pin 26 is low, look at the power on reset circuit.
The Z80 only needs a short low pulse to reset itself.
It must he high for the Z80 to run.
charminator
Posts: 18
Joined: Tue Apr 17, 2018 8:38 am
Location: Germany, Hamburg

Re: MZ-80K displaying garbage chars on screen

Post by charminator »

fetch all RAM ics and clean the contacts ... i just had this issue with some dust on the chips. And i had to replace my system EPROM ... a fresh burnt one runs fine.
Have an eye on the tantal caps inside the powers supply and dont forget to check the cap in the power SWITCH ;)
Collecting -K- since 1978

Supporter of Karl Heinz Maus famous MZ site ;)
hlide
Posts: 681
Joined: Thu Jan 25, 2018 9:31 pm

Re: MZ-80K displaying garbage chars on screen

Post by hlide »

Good! :)
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