Yes, I am a bit ignorant on this issue unfortunatelyPerhaps I need to do a little “teach in” for you based on this specific fault. Would that help?
Hi Dave,Yes, if you touch UA3 and the noise pattern changes on the screen - you may have found the culprit.
Equally well, it could also be the ROM... But this is the last scenario you should consider. Assume it is a contact problem first.
As an aside, if you are going to be repairing vintage computer equipment as part of a hobby - then can I suggest writing out a list of tools and test equipment you will need. As time progresses, you could consider purchasing some more useful tools. The top of the list would be a better oscilloscope - along with learning how to use it. Finding noise issues like this is relatively easy with an oscilloscope - but you do need to know what 'good' and 'bad' looks like. Unfortunately, this can only really be determined by looking and experience.
Dave
Eheheh Dave...when i finished the pet ... i have a dual floppy to connect and test if it worksThis is the PET machine that just keeps on giving!
The character generator must have been failing for it to be sensitive to the electromagnetic field you were inducing into it from your body.
Let's see what happens when you get the replacement 6520s...
We finally finished our jigsaw. We are just debating breaking it up and doing the other side (it is two for the price of one). My wife is not too keen about this - but my son is up for it...
Dave
>>> sometimes I turn on and get a black or blank screen or just a few words ....
With EDIT ROM in place!Is that with the PETTESTER or the proper EDIT ROM in place?