New Membrane Malfunction

Nagging hardware related question? Post here!
User avatar
Cristian
Gold Card
Posts: 464
Joined: Mon Feb 16, 2015 1:40 pm
Location: Veneto

Re: New Membrane Malfunction

Postby Cristian » Tue Mar 21, 2017 9:10 pm

Rich and Dave,
thanks to your hints now my keyboard seems OK :-)
To be accurate, the little holes in the membrane seem not precisely centered with the little plastic pivots, so the membrane looks slightly grooved. But apparently this don't affect the good keyboard function. I suppose this is due to the metallic plate that flattens the membrane and correct the little grooves


User avatar
Dave
SandySuperQDave
Posts: 1996
Joined: Sat Jan 22, 2011 6:52 am
Location: Austin, TX
Contact:

Re: New Membrane Malfunction

Postby Dave » Tue Mar 21, 2017 9:14 pm

Glad that between us we got you sorted, one way or another.


Silvester
Trump Card
Posts: 185
Joined: Thu Dec 12, 2013 10:14 am
Location: UK

Re: New Membrane Malfunction

Postby Silvester » Thu Apr 13, 2017 1:43 pm

miked

Just a thought, as a quick check that the 8049 is actually up and running (maybe faulty 11MHz crystal?) do you hear a click from the speaker when you press RESET button. Since it is driven from output pin of 8049, if it is dead it shouldn't click.

If OK, are 8049 keyboard outputs strobing? (any pin on J11 connector)

The next best test would be using a Minerva ROM to see if, after it times out F1/F2 prompt, it displays normal windows and flashing cursor.


User avatar
kordics
ROM Dongle
Posts: 11
Joined: Tue Apr 12, 2016 6:30 pm
Location: Kotor, Montenegro

Re: New Membrane Malfunction

Postby kordics » Sat Feb 17, 2018 9:45 pm

I have finally found what was the problem with my QL and maybe it can help some other members of the forum!

I have replaced faulty Intel 8049 coprocessor & old keyboard membrane with a new one. After changes, I could reach F1/F2 screen and then nothing more, since keyboard/membrane was completely unresponsive. I thought that it was something wrong with either membrane or some of the two molex connectors.

Yesterday evening I had a time and I removed and re-seated all socked chips, except 8049, but that didn't help. Finally, I re-seated 8049 and my QL was again operable, just as it was in 1985 when I bought it! So, the cause of the problem was bad re-seating of 8049!

Now, I couldn't be more happier! After not managing to fix my original QL, I bought another one from UK. That means the I have 2 operable machines. QL networking here I come…

Saluti,
Stevan


User avatar
1024MAK
Super Gold Card
Posts: 515
Joined: Sun Dec 11, 2011 1:16 am
Location: Looking forward to summer in Somerset, UK...

Re: New Membrane Malfunction

Postby 1024MAK » Sat Feb 17, 2018 11:55 pm

Well done :D

Mark


QL, Falcon, Atari 520STFM, Atari 1040STE, more PC's than I care to count and an assortment of 8 bit micros (Sinclair and Acorn)(nearly forgot the Psion's)
User avatar
Cristian
Gold Card
Posts: 464
Joined: Mon Feb 16, 2015 1:40 pm
Location: Veneto

Re: New Membrane Malfunction

Postby Cristian » Sun Feb 18, 2018 2:01 pm

kordics wrote:That means the I have 2 operable machines. QL networking here I come…

:-)



Return to “Hardware”

Who is online

Users browsing this forum: No registered users and 7 guests