A3000 motherboard mod near U254

ajk · 18 November 2017, 16:39

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?

nogginthenog · 18 November 2017, 18:00

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.

pandy71 · 18 November 2017, 19:01

Too much solder on iron tip dropped in very bad place...? probably cooled very quickly and should be easy to be removed manually...

ajk · 18 November 2017, 20:33

Interestingly I haven't noticed any side effects, at least nothing severe. I will clean it up and see if anything changes.

ajk · 19 November 2017, 00:37

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!

r.cade · 19 November 2017, 03:54

That was very lucky!

pandy71 · 19 November 2017, 13:50

Quote:

Originally Posted by ajk

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!

ajk · 19 November 2017, 13:53

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.

idrougge · 20 November 2017, 13:50

The A3000 PLCC sockets are quite brittle.

A10001986 · 21 November 2017, 11:37

And if you replace them, use 3M ones. I bit more expensive, but definitely better in the long run.

ajk · 21 November 2017, 12:53

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.

DH · 21 November 2017, 13:05

Quote:

Originally Posted by ajk

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.

ajk · 21 November 2017, 13:06

Sounds good, and if it can be done automatically, even better

18 November 2017, 16:39	#1
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	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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18 November 2017, 18:00	#2
nogginthenog Amigan Join Date: Feb 2012 Location: London Posts: 1,311	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.

18 November 2017, 19:01	#3
pandy71 Registered User Join Date: Jun 2010 Location: PL? Posts: 2,771	Too much solder on iron tip dropped in very bad place...? probably cooled very quickly and should be easy to be removed manually...

18 November 2017, 20:33	#4
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	Interestingly I haven't noticed any side effects, at least nothing severe. I will clean it up and see if anything changes.

19 November 2017, 00:37	#5
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	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!

19 November 2017, 03:54	#6
r.cade Registered User Join Date: Aug 2006 Location: Augusta, Georgia, USA Posts: 550	That was very lucky!

19 November 2017, 13:53	#8
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	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.

20 November 2017, 13:50	#9
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,338	The A3000 PLCC sockets are quite brittle.

21 November 2017, 11:37	#10
A10001986 Registered User Join Date: Jun 2017 Location: 1986 Posts: 79	And if you replace them, use 3M ones. I bit more expensive, but definitely better in the long run.

21 November 2017, 12:53	#11
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	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.

21 November 2017, 13:06	#13
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	Sounds good, and if it can be done automatically, even better

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