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Iss. 5 resurrected, but flickering/freezing
Posted: Sun Oct 10, 2021 9:51 pm
by af0l
I have this sweet iss. 5 on my hands that was pronounced dead. After inspecting it thoroughly, everything seemed fine except:
- CLA2310 was dead
- 8049 was dead
- spider mod was undone
I fixed the issues, but still this flicker/freeze is happening. Any ideas?
P.S. I also replaced all the capacitors
Video here:
https://youtu.be/BsxUu9OoMbk
Re: Iss. 5 resurrected, but flickering/freezing
Posted: Sun Oct 10, 2021 10:34 pm
by mk79
As always the first question is "does the monitor work correctly with another QL"?
Re: Iss. 5 resurrected, but flickering/freezing
Posted: Sun Oct 10, 2021 10:53 pm
by af0l
Yes, forgot to say that. I have my iss. 7 that works fine with this monitor/tv and scart cable.
Re: Iss. 5 resurrected, but flickering/freezing
Posted: Mon Oct 11, 2021 7:52 am
by mk79
RGB scart cable? There's basically no other component between the ZX8301 and the RGB output (which is why it so often dies)... the only other component involved is the RGB connector, maybe that has contact problems?
Re: Iss. 5 resurrected, but flickering/freezing
Posted: Mon Oct 11, 2021 9:52 pm
by af0l
That is an excellent Idea. I checked the connector and solders, they are solid. But then it dawned on me to recheck the voltages and all sorts of fun was happening on the 12V rail.
In the end it was my silly idea to socket the 1488, in orderr to redo a "clean" spider mod on the ULA, that was removed. I managed to turn the IC upside down... I am deeply ashamed, the only consolation being that the QL seems rock solid now.
Thank you for your ideas mk79.
Re: Iss. 5 resurrected, but flickering/freezing
Posted: Mon Oct 11, 2021 10:54 pm
by mk79
Ha, at least you caught it, that would have been difficult to debug remotely
Glad it works now!
Re: Iss. 5 resurrected, but flickering/freezing
Posted: Sat Oct 16, 2021 3:08 pm
by af0l
Alas, all is not well still. The F1/F2 screen comes up, but then everyttnig freezes. Nothing happens when I press the keys.
New membrane. New 8049. One of the 74257's had a faulty gate, fixed that, did not help. I also swapped the line drivers from my working machine - same results.
Open to all ideas...
Re: Iss. 5 resurrected, but flickering/freezing
Posted: Sat Oct 16, 2021 4:18 pm
by af0l
OH, it was the silliest of things... ROM failed... All seems well now
