ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi guys,
I've got two MCP 5000 each one half faulty, beside the usual blinds led bars.
First one do work exept columns 6 (TP1/2, Phono, Aux) and row 7 (Return green, Stop, Return white, <<).I've searched for broken traces, dirty contact in keys or broken ribbon wire but found nothing.No obvious marks of leakage, burn or rust.
Second one do work exept once in stand by it wont work again (similar to many Beo4 I have). If I take out the cells and insert them again, it will work until stand-by. No obvious damage inside.
The Service Manual being not very detailed (unless I dont know how to read it) could someone point me where to start. I've searched the forum but didnt found much information on those problems.
Thanks.
On MCP 5000 A (with non working row of keys).
Checked strobe output from IC=was OK.Checked strobe on D9 output=was OK. Checked Keyboard at Ribbon cable by pressing keys=OKChecked continuity at Ribbon cable for sucked keys=All OK
I'll check strobe signal at IC Keyboard input tomorrow but I think it can't be that or the problem would be by columns instead of row, isn't it? (as per schematics).
Do I miss something obvious?
Thank you for any help.
This morning I figured out i was using an idiot process: I checked at different test points but not BETWEEN the test points.So the keyboard did work, the strobe signal did make it through D10 but there was an (invisible) cut between keyboard pin 10 and D10.A strap did solve the issue. i want to thank a friend who supported me all along the process.
Of course an educated technician would have checked this first and avoid a deep and not so easy dismantling, but I'm happy still because in the process I learned a lot about thinking and refining the search to find the fault and using different test tools.
Hope it will help somebody one day.