SOLVED !! not a happy ql , but what causes it ??

[techy]

this is how it looked on monday-morning ;

And THIS is how it lookes now ;

and it lookes like this with and without the gold-card , minerva , and hermes

tried on cv-out and rgb , both display the lines .

Any help is help .............

[bwinkel67]

Looks like you are loading a ZX81 program from cassette and it's close to the end of the load :-/

[techy]

unfortunately , that is not the case ................

[bwinkel67]

If you weren't running Minerva I'd speculate it's RAM, but I think Minerva gives a code if it is. Check out this forum post as the first image looks similar to your (tough there is some additional part that yours doesn't have). You could PM the original poster to see if they ever solved their issue. Hope that helps:

viewtopic.php?t=3807

[bwinkel67]

...oh, and I found another post on this forum with similar display:

viewtopic.php?t=2811

...and here is what Dave said about the black and white lines:

The pattern in the screen shot is ROM copied into RAM.

There is no failure pattern of RAM that would cause that image. Solid black or white bars indicate 8 ICs all returning a 0 or 1 bit together. If one RAM IC was asserting or de-asserting on address lines, it would have to be either A14 or A12 or both to make a pattern that changes in that way.

The 8301 only cares about A16 and A17, so it is likely ok.

The only place all those items come together is the CPU and the crappy CPU socket on your UK Issue 5 QL...

So yes, confusing.

Good luck tracking it down...

[jobdone]

Try reseating the roms, the CPU and the zx8301( In that order) also check for bent pins on the roms. I would also say the above answer (from Dave is correct) the only time I've seen this pattern is when I've been playing with roms or they are not seated correctly, of course the path to and including the CPU. so would a bent edge pin cause this too?

[jobdone]

I do remember seeing a post elsewhere about a stuck reset switch causing this too. I've only ever seen this when I've been playing with roms and that thought also reminded me if using a third party Minerva board, make sure the jumper is on. Corrosion on that too might be an issue as well as a socketed ROM.

[techy]

thank you all for your reply ,

It will be testing-day on saturday !!

[techy]

first test update ;

cpu , does not change a thing
rom's , do not change a thing
8301 , does not change a thing
reset button , does not change a thing

all parts taken from a working ql , and put back after the test the donor ql works fine


Heeeeeeeeeeeeeeeelp

[jobdone]

In which case, check what was wrong with the guy on fbook. Stuck reset. In his case stuck button..