asdf87 Posted December 12, 2020 Share Posted December 12, 2020 (edited) Greetings from Australia. I'm finally having a go at repairing my CC40. It had battery leakage damage which I've repaired - scrubbed the contacts clean and soldered in new wires. There was some damage on the ground plane too - it had gotten under the conformal coating too so I removed the coating and cleaned the blue residue off. I also took the opportunity to completely disassemble and clean the case and keys. Otherwise, I can't see any obvious damage. However it won't power on. Using either batteries or my 6VDC bench supply I can only get half the screen whilst I hold the power button down. Letting go of the button switches off again. Will start poking around but thought I'd check here in case any of the far more experienced people knew where I should zero in on (i've got an oscilloscope, logic analyser, etc.). Thanks, Brett. Edited December 12, 2020 by asdf87 typo Quote Link to comment Share on other sites More sharing options...
asdf87 Posted December 13, 2020 Author Share Posted December 13, 2020 I found my second CC40 (used) and it does remain powered on but shows the same half-screen of characters as this one - so that'll be the second issue I need to fix I guess Quote Link to comment Share on other sites More sharing options...
+dhe Posted December 13, 2020 Share Posted December 13, 2020 Have you tried just going through the motions and typing beep <enter> - maybe it's a screen only issue? Quote Link to comment Share on other sites More sharing options...
asdf87 Posted December 13, 2020 Author Share Posted December 13, 2020 (edited) 1 hour ago, dhe said: Have you tried just going through the motions and typing beep <enter> - maybe it's a screen only issue? Thanks for replying. I gave it a try: [1] Holding down ON button and typing beep<enter> gave no sound or displayed anything other than my original pic [2] Pressing ON then releasing - screen displays then disappears - typing beep again gave no sound or other display I can see the CPU gets +5V when I press/hold the ON button but this disappears when I release it. I'm not familiar with how these "soft" ON buttons work - I'm assuming some sort of transistor is involved - I can see the ON button goes via a transistor to the left of the speaker/ribbon cable ... ? In the picture, the ON button is the two left-most tracks on the ribbon cable (IIRC) Edited December 13, 2020 by asdf87 Added picture Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted December 13, 2020 Share Posted December 13, 2020 Hmm, I found some anomalies, probably not the current issue, but still worth a go over ...perhaps. Leftover solder splatters - Yellow Possible bridge - Red Leftover solder splatters - Red whisker connection - Yellow It looks like you're only showing one side of each board... ...maybe there's more to be discovered? Quote Link to comment Share on other sites More sharing options...
asdf87 Posted December 13, 2020 Author Share Posted December 13, 2020 17 minutes ago, HOME AUTOMATION said: Hmm, I found some anomalies, probably not the current issue, but still worth a go over ...perhaps. It looks like you're only showing one side of each board... ...maybe there's more to be discovered? Oh wow, thanks! Sorry for my earlier, shoddy photos I've taken a snap of each board, but I'll have a look at those bit you highlighted already. I was wondering whether the pair of transistors near the speaker were for the soft ON/OFF ... maybe a BC237 and a 2N2222A? Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted December 13, 2020 Share Posted December 13, 2020 One other thing I see--the square surface mount chip (1041036-1) has been replaced. Double-check all of the connections there, as the solder job looks a bit sloppy and the pins are really close together. Quote Link to comment Share on other sites More sharing options...
asdf87 Posted December 13, 2020 Author Share Posted December 13, 2020 3 hours ago, Ksarul said: One other thing I see--the square surface mount chip (1041036-1) has been replaced. Double-check all of the connections there, as the solder job looks a bit sloppy and the pins are really close together. Yep, you're right, now that I look at it closely there appears to be a lot of flux residue around that one chip. All the connections "look" okay with a loupe but will double check it. Quote Link to comment Share on other sites More sharing options...
+dhe Posted December 13, 2020 Share Posted December 13, 2020 Just like I asked about beep, just in case it was just the screen, did these work at one time, and just quit when you pulled them out of storage? Quote Link to comment Share on other sites More sharing options...
asdf87 Posted December 13, 2020 Author Share Posted December 13, 2020 Just now, dhe said: Just like I asked about beep, just in case it was just the screen, did these work at one time, and just quit when you pulled them out of storage? Unknown - I got them off eBay last year, or earlier this year. They didn't immediately work so I put them aside until I had time to try to figure out the problems. Quote Link to comment Share on other sites More sharing options...
+dhe Posted December 14, 2020 Share Posted December 14, 2020 ok... thanks... just establishing a baseline... Anything could have happened to these. I think you mentioned you have a scope... I think I'd check to see if Mr. Crystal was working and then see if you see anything on the data or address lines on start up. Quote Link to comment Share on other sites More sharing options...
+acadiel Posted December 14, 2020 Share Posted December 14, 2020 Here's the schematics. 2 Quote Link to comment Share on other sites More sharing options...
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