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Old 18 November 2017, 17:39   #1
ajk
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A3000 motherboard mod near U254

Hi,

I was working on my A3000 and noticed this solder blob in the front left section:



Does anyone know or recognize what this is for? I tried googling for photos of other rev 9.3 motherboards, but they don't seem to have this. And in any case it seems pretty poorly done. Can this be simply removed, or should I recreate the mod on the underside of the motherboard?
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Old 18 November 2017, 19:00   #2
nogginthenog
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I don't think it's deliberate.

Pins 17-20 of that 74F245 are connected.
Pin 20 is power and 19 is Output Enable.

OE is active low and it's connected to power (i.e. high) so the chip will never be enabled.
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Old 18 November 2017, 20:01   #3
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Too much solder on iron tip dropped in very bad place...? probably cooled very quickly and should be easy to be removed manually...
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Old 18 November 2017, 21:33   #4
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Interestingly I haven't noticed any side effects, at least nothing severe. I will clean it up and see if anything changes.
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Old 19 November 2017, 01:37   #5
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Well it's cleaned up now and the system seems to work still. I guess it was just some splashed solder then. Pretty lucky that it didn't actually shortcut anything important!

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Old 19 November 2017, 04:54   #6
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That was very lucky!
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Old 19 November 2017, 14:50   #7
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Quote:
Originally Posted by ajk View Post
Interestingly I haven't noticed any side effects, at least nothing severe. I will clean it up and see if anything changes.

Solder solidified to quickly and was unable to create electric connection (probably IC pins oxidized).

And yes - you are very lucky!
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Old 19 November 2017, 14:53   #8
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I must point out that it's not something I did, must have been either the previous owner or even from factory Several of the PLCC sockets were broken so perhaps someone has been working on the board in the years past. Got them all fixed now.
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Old 20 November 2017, 14:50   #9
idrougge
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The A3000 PLCC sockets are quite brittle.
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Old 21 November 2017, 12:37   #10
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And if you replace them, use 3M ones. I bit more expensive, but definitely better in the long run.
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Old 21 November 2017, 13:53   #11
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I already did. Not sure if these were specifically 3M but they are definitely much more solid than the old ones (Agnus socket is the new one in the photo).

I also made GAL versions of the original PAL chips, they sure run much cooler.

BTW, is there some way to resize images directly in BBCode? I tried [img=640x480] and other variants but it doesn't seem to work. It's a pain to manually make different sized versions of photos and the attachment size limit is so small that it's hard to include images that way either.

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Old 21 November 2017, 14:05   #12
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Quote:
Originally Posted by ajk View Post
BTW, is there some way to resize images directly in BBCode? I tried [img=640x480] and other variants but it doesn't seem to work. It's a pain to manually make different sized versions of photos and the attachment size limit is so small that it's hard to include images that way either.
Unfortunately not, although RCK may implement something to reduce the size for normal viewing but have an option to view at the original size if people wish to.
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Old 21 November 2017, 14:06   #13
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Sounds good, and if it can be done automatically, even better
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