Revolution X cap leak-o-rama

Those traces are at the RCH level - they are so fine.
 
Bummer. But I'm not surprised. There's a reason these boards gets tossed when the caps leak and why nobody offers to work on them. It's almost always a lost cause. But if you have the time and determination, anything can be fixed. Two of the issues that are really hard to find are eaten traces/vias under surface mount components and chips that have gone bad by the corrosion/electrolyte creeping inside the chips via the corrosion/electrolyte on the legs.
For sure it's not easy; i'm not an expert but I have enough soldering skills to make a good attempt. I might pickup some new 245 & 374 chips and give that a go. Fortunately @irepairsega does fix these boards and he's somewhat local to me. If I run into a wall i'll have to accept defeat and bring in the expert!
 
@zenomorp, i'm pretty sure these ICs are functionally equivalent; can you confirm? Or maybe share where you sourced yours?

1740179023493.png
 
I didn't replace mine. Just removed them, cleaned the oxidized pads/legs, and reinstalled them.
I thought you replaced them from a donor?

 
Thus far, I've now replaced all the SMC caps and checked the adjacent traces. Almost all the caps have a small trace that run to a via hole that carries the connection to the back (or inside) of the board somewhere else.

Basically each cap you have to verify there is continuity from the pad, to the via, and the via to wherever it goes.

So that work is done, and I have done a ton of trace repair, but we have nothing but a grey screen.

Next steps are to pull and dump the roms to make sure they are ok.

I have some 245 & 374 chips on order that I believe are correct and will try swapping them out. Fortunately they come right off with hot air, so should be reasonably easy.

After that I'm out of ideas!

IMG_2788.jpeg
 
So I just finished dumping the ROMs; either I have a un-dumped version or more than half my chips are missing data? I'm not really sure if that's possible.

C:\mame>mame64.exe -romident revx.zip
Identifying revx.zip....
U101.bin NO MATCH
U102.bin NO MATCH
U103.bin = revx.103 revx Revolution X (rev 1.0 6/16/94)
= revx.103 revxp5 Revolution X (prototype, rev 5.0 5/23/94)
U104.bin NO MATCH
U110.bin NO MATCH
U111.bin NO MATCH
U112.bin NO MATCH
U113.bin = revx.113 revx Revolution X (rev 1.0 6/16/94)
= revx.113 revxp5 Revolution X (prototype, rev 5.0 5/23/94)
U120.bin NO MATCH
U121.bin NO MATCH
U122.bin NO MATCH
U123.bin NO MATCH
U51.bin = revx.51 revx Revolution X (rev 1.0 6/16/94)
= revx.51 revx Revolution X (rev 1.0 6/16/94)
U52.bin = revx.52 revx Revolution X (rev 1.0 6/16/94)
= revx.52 revx Revolution X (rev 1.0 6/16/94)
U53.bin = revx.53 revx Revolution X (rev 1.0 6/16/94)
= revx.53 revx Revolution X (rev 1.0 6/16/94)
U54.bin = revx.54 revx Revolution X (rev 1.0 6/16/94)
= revx.54 revx Revolution X (rev 1.0 6/16/94)
U63.bin = revx.63 revx Revolution X (rev 1.0 6/16/94)
= revx.63 revxp5 Revolution X (prototype, rev 5.0 5/23/94)
U64.bin NO MATCH
U65.bin = revx.65 revx Revolution X (rev 1.0 6/16/94)
= revx.65 revxp5 Revolution X (prototype, rev 5.0 5/23/94)
U66.bin NO MATCH
U71.bin = revx.71 revx Revolution X (rev 1.0 6/16/94)
= revx.71 revxp5 Revolution X (prototype, rev 5.0 5/23/94)
U72.bin NO MATCH
U73.bin NO MATCH
U74.bin NO MATCH
U81.bin = revx.81 revx Revolution X (rev 1.0 6/16/94)
= revx.81 revxp5 Revolution X (prototype, rev 5.0 5/23/94)
U82.bin NO MATCH
U83.bin NO MATCH
U84.bin NO MATCH
U91.bin NO MATCH
U92.bin NO MATCH
U93.bin = revx.93 revx Revolution X (rev 1.0 6/16/94)
= revx.93 revxp5 Revolution X (prototype, rev 5.0 5/23/94)
U94.bin NO MATCH
Out of 32 files, 11 matched, 21 did not match.
 
Checking my labels, they did indeed say "rev 1" which I will take as a 1.0 version at least:
 

Attachments

  • IMG_2792.jpeg
    IMG_2792.jpeg
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Wondering about the ROM dump; is it possible to have so many bad chips? Or do I just have a un-dumped version? I compared my dump to ver1.0 and prototype v5. I haven't found any other versions online.
 
Wondering about the ROM dump; is it possible to have so many bad chips? Or do I just have a un-dumped version? I compared my dump to ver1.0 and prototype v5. I haven't found any other versions online.
Yes, it is possible. If the checksum doesn't match, it's a problem.

I have seen tin whiskers in chips going between internals shorting stuff out. Try to re-flash the ROMS or get in touch with @steph at Hobby Roms and see if you can get some from him.
 
Thus far, I've now replaced all the SMC caps and checked the adjacent traces. Almost all the caps have a small trace that run to a via hole that carries the connection to the back (or inside) of the board somewhere else.

Basically each cap you have to verify there is continuity from the pad, to the via, and the via to wherever it goes.

So that work is done, and I have done a ton of trace repair, but we have nothing but a grey screen.

Next steps are to pull and dump the roms to make sure they are ok.

I have some 245 & 374 chips on order that I believe are correct and will try swapping them out. Fortunately they come right off with hot air, so should be reasonably easy.

After that I'm out of ideas!

View attachment 802409
only the top row of roms in the picture without labels are the program roms, the rest are graphic roms that are the same between P5 and L1. I made the mistake of reprogramming all 32 roms once. :ROFLMAO: I am uncertain about why so many roms are showing bad. that will probably remain an unsolved mystery.
 
only the top row of roms in the picture without labels are the program roms, the rest are graphic roms that are the same between P5 and L1. I made the mistake of reprogramming all 32 roms once. :ROFLMAO: I am uncertain about why so many roms are showing bad. that will probably remain an unsolved mystery.
Ok, given these all check out fine, then it might be the 245/347 chips that @zenomorp had mentioned in his video.

I already reflowed mine, but the 245 chips at U39 & U17 got a lot of corrosion on their legs, and possibly inside the chip:
1740606548525.png1740606500207.png

Especially U39, being directly tied to the reading of the program code might need to be replaced. I have some on order.
 
Do you know if the board is just a 2 layer board or a multilayer board with internal traces? If multilayer then some of the vias may go to internal layers.
 
Do you know if the board is just a 2 layer board or a multilayer board with internal traces? If multilayer then some of the vias may go to internal layers.
I'm pretty sure it's a multilayer; there are some vias on the caps that go no where on the backside. I had to tone a few out to figure out where they went.

This guy for example. The Positive side goes to the resistors on the right, the neg grabs a ground somewhere, but no traces on the back.

1740607982156.png
 
Do you know if the board is just a 2 layer board or a multilayer board with internal traces? If multilayer then some of the vias may go to internal layers.
yes Williams may have used multi layer since NARC Z-unit. I know for certain from T-unit onward is multi layer.

I'm pretty sure it's a multilayer; there are some vias on the caps that go no where on the backside. I had to tone a few out to figure out where they went.

This guy for example. The Positive side goes to the resistors on the right, the neg grabs a ground somewhere, but no traces on the back.

View attachment 802652
weren't the roms showing bad in your programmer? also if the goop gets on the chip legs it does trickle inside and will wreck TTL.
 
Yeah, i'm pretty sure that the 2 chips I pictured above are toast. The corrosion was much worse than pictured, these are mosly cleaned up with deoxit.
 
Yeah, i'm pretty sure that the 2 chips I pictured above are toast. The corrosion was much worse than pictured, these are mosly cleaned up with deoxit.
I would think so the legs look pretty bad you could not get then any cleaner or were you worried about them breaking off at the chip? Some of those legs have to be bad
 
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