Thread: Zx81
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Old 28th Apr 2020, 9:25 pm   #290
Slothie
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Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 1,168
Default Re: Zx81

Quote:
Originally Posted by John Earland View Post
Quote:
Originally Posted by Slothie View Post
John, I can't recall if you have replaced or tested the power supply electrolytics and any on the board? Poor smoothing can cause all kinds of intermittent and temperature related problems.
Hi, no I havenít tested that yet. I donít have access to an oscilloscope etc-minimal equipments really. :-(
If you can find a 20uF or larger capacitor and put it temporarily across C3 (or just replace C3) that would show if you have a problem. Just be sure to connect them the right way round. Since there are so few on the ZX81 and power supply, RAM pack it might just be worth replacing them all since they are likely to be failing after 40 years even if they appear to be functioning.
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