130XE Problem - "Corrosion" on solder joints (power, RF and trim)

[bbking67]

I found an old 130XE in my archives tonight and this one was marked as not working. I took a look at the motherboard, and of course it has the dreaded Micron DRAM. it's a 16-chip Rev. 5 motherboard. I'm not sure it's worth restoring, but in any case there is a problem I am not familiar with.

 

First of all when powered up, the system's LED does not come on, but the screen goes black with no sound (I am using RF).

 

Upon examination, the motherboard appears to have some kind of white residue underneath the power switch, trim pot, and RF modulator (possibly a couple of other locations as well). It's not too visible on the top of the board.

 

is this fixable? Where to start... replace RAM perhaps?

 

/bbking67

[Rybags]

Fixable of course. So long as the motherboard is intact and doesn't have broken traces everywhere it can still be brought back.

 

Where to start... that's tricky. Given the XEs tend to not have sockets, it means you can't just pull and test the major chips in another machine.

 

If you've got a flashcart you could try making a diagnostic cart and using it to test for signs of life.

[bbking67]

What is the corrosion caused by? Do you think I just need to redo the connections to the various components?

[Rybags]

Probably cheap-arsed solder from original construction... plus the fact you're dealing with a ~ 25 year old machine, plus the fact it might have been stored in a humid environment for some time.

 

You could continuity test some samples of the joins from chip pin to chip pin.

 

If you don't have the skill/confidence to desolder stuff then you're probably better off sending it to sloopy or someone with the skill to fix it.

Problem is, a 2 way journey through the postal system alone might cost almost as much as you'd pay for a working replacement machine.