Try repair an a4000 motherboard - help

[roy bates]

loedown, i like the way you think,not only that but you "improvised".

sometimes you have to do things like this,to make repairs possible.

roy.

[8bitbubsy]

TTD, the resistor values are probably OK for what they are used in (there's no such thing as negative ohm).
I think you should desolder the SMD caps and install new ones. Don't bother with the two big through-hole caps yet, as they are a pain in the butt to desolder without a very stable soldering iron with a thick tip. Not to mention removing the solder from the ground plane hole.

[Loedown]

Originally Posted by roy bates

loedown, i like the way you think,not only that but you "improvised".

sometimes you have to do things like this,to make repairs possible.

roy.

I never see the point in wasting things just for the sake of it, we live in far too much of a 'throw away society' and there's no need for such.

I am a notorious horder for exactly this reason. I have a project that will be done soon which is a cable tester and cable investigator, meaning that if you have a cable with a D25 at each end it will tell you where each wire goes.

Will also do network cables, HDMI, USB, serial, firewire and anything else I can find. All this becomes possible because I have old PC motherboards here with connectors on them.

[TTD]

@8bitbubsy If there is no negative ohms then why do I get the readings? because of the ic on different locations is defective?

[8bitbubsy]

I've never ever heard about "negative ohm", maybe it happens if you measure resistance through a line with current in it?

[Loedown]

Originally Posted by 8bitbubsy

I've never ever heard about "negative ohm", maybe it happens if you measure resistance through a line with current in it?

This is close enough, if voltage is present when measuring resistances then it can sometimes show a negative resistance, mainly from charged capacitors and alike.

[TTD]

Sorry have not reply to this for long and thanks for all help and info I can get.

I have try used a toothbrush and not lemon juice but lime instead, also use isopropyl achohol it did job and rails should be working near battery on a4000 motherboard on location u177.

I also try repair an a500+ rev 8 motherboard.

I have also work on a500+ motherboard which has very heavy battery leakage (I have seen fitzsteve have some near that or same when searching on battery leak remove)

I was doing on that first with lime + toothbrush, water and isopropyl alchol.

I through it was dead, since I got this motherboard free from a friend that say it was dead.

I have try get the plug for keyboard from motherboard on a4000 but that is hard to get rid off, with my small soldering skills so still practice on my a500+ I have removed battery some resistors checked these and should work there is a capasistor that I dont know to test, on open circuit the place on the a500+ motherboard name on location c913 with these looking on service guide - says:
mlc axial npo 22pF
- so how do I check it - because this is very greeny from acid.

It looks that I need to replace it with a new one, but most capasistors I have as spare is with uF and not pF.

[roy bates]

dont bother checking the capacitor,just replace it.

there very cheap and easy to get.

roy.

[TTD]

Thanks for advice roy_bates I will do when I have got my spare parts to repair with I try make a list of components I need for my repairs.

EDIT Updated

Well some other jobs have be more on focus than fixing my a4000 problem and still need the electronic component list done, before bying these.
I also try fixing som atx psu and my a500+.
I should also get one of my friends old laptop and or old amigas soon so maybe I need to see what to repair on these too, before buying electronic components.

[TTD]

Case is more or less inactive at the moment