User avatar
leighb2282

Posted Mon Jan 22, 2018 11:26 pm

Hello again folks!

Recently I bought an TC coin cell battery replacement for my A2000, the original Varta barrel battery had leaked somewhat but not to a terrible degree and I wanted to get the RTC back working.

Firstly, it WORKED! it now happily keeps time even after unplugging the mains power, which is quite a thrill after the journey to get in on there.
battery.jpg
Secondly HOLY !$?&%!@# is the solder they used terrible to get off the motherboard after its had a Varta acid bath! Honestly I was afraid I was bricking the motherboard due to teh amount of heat I was having to use to get the final pin removed and the hole unclogged even with a Solder sucker, the old solder refused to melt and when it finally did reflow the old pin kept hanging in the hole, after about 15 minutes of feeding more and more solder into the hole it was enough to push the old battery lin out and I was then able to suck away all the additional solder but for a while there I was expecting the worst.

Thirdly, I got introduced to those dreaded colored bootup screens, when I initially replaced the battery I wanted to test everything was ok with the minimum of upgrades in the machine, so I tried booting it up with just the floppy, not SCSI card, no additional RAM, no accelerator card, well, first I got a green screen, then a cyan screen, re powered the machine and got green and then pink, rinse repeat, so I double checked all my wiring, narrowed it down to it being sensitive to which floppy drive power connector I used; it was failing when I used the 'terminating' plug, but the one in the middle worked fine.

Fourthly(?) it seems Either GVP or the people I bought my accelerator from were being sneaky, the 68030 CPU and 68882 FPU are both 25Mhz chips, but the Crystal Oscillator that they used was running at 28Mhz, so i've been effectively overclocking my processor without even knowing it :( the only bonus from this is I found out the oscillator is actually in a socket, so I can in theory get a 50Mhz CPU/FPU and up the speed of the oscillator easily!

Fifthly(?) Commodore really didn't want people to get to the bottom of the motherboard, its a right pain to get that exposed (all the screws to remove the motherboard including 2 which sneakily go through DB sockets, and then you have to remove all the hexagonal screw receptacles before you can take the shield off!

I'm not complaining because she now has a working RTC again, but its has been 3 hours with a roller coaster of emotions and I needed to vent/ramble.

User avatar
Zippy Zapp
CA, USA

Posted Tue Jan 23, 2018 8:56 am

Yeah that corrosion is a bear to deal with when unsoldering. For those batteries, when I did the 2nd one, I snipped the battery out and left the legs behind. It was easier to unsolder that way.

Anyway, glad you got it all sorted and working. I still have one A2000 left to do. Battery is out, just need to put in a replacement.

User avatar
intric8
Seattle, WA, USA

Posted Tue Jan 23, 2018 9:19 am

Secondly HOLY !$?&%!@# is the solder they used terrible to get off the motherboard after its had a Varta acid bath! Honestly I was afraid I was bricking the motherboard due to teh amount of heat I was having to use to get the final pin removed and the hole unclogged even with a Solder sucker, the old solder refused to melt and when it finally did reflow the old pin kept hanging in the hole, after about 15 minutes of feeding more and more solder into the hole it was enough to push the old battery lin out and I was then able to suck away all the additional solder but for a while there I was expecting the worst.
I can totally related to this! I've unsoldered batteries from 3 Amiga 2000s. I was able to successfully save 2 boards. The third had indeed died a tragic death. And the original solder was really nasty stuff. Maybe back then it was just solid lead. Or melted down galvanized pipes from ancient times - who knows! It's really not easy to remove - you're right.

Glad to hear you were able to get it back up and running. Well done!





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