Midway Gunfight

MrSinister

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Donor 9 years: 2015-2022, 2024
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Working on one for a friend from work. Who here repairs the pcbs and power supplies or can recommend someone else that does?

The fuses were blown and he never tried to power it on.
The 2n2905 on the power supply gets insanely hot.
8080 cpu had multiple legs corroded off. 1000003057.jpg
 
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Working on one for a friend from work. Who here repairs the pcbs and power supplies or can recommend someone else that does?

The fuses were blown and he never tried to power it on.
The 2n2905 on the power supply gets insanely hot.
8080 cpu had multiple legs corroded off. View attachment 726245
Wow. Gold (noble) legs corroded off.

Any idea what got to them?
 
I've seen legs rot on both gold and regular leads. After cleaning the legs are left if there is some of the original pin exposed you can solder on a new pin. I kept some dead EPROM chips just for the leads when I need some. Just recently had to fix some mask ROM's that way.

Chances are high that you'll need to replace the DIP sockets on that main MPU board and probably the four 10uf electrolytic caps too.
 
Less fecal, more urine and mouse house. But yes much of the same. The pcb took the grunt of the urine damage.
 
Working on one for a friend from work. Who here repairs the pcbs and power supplies or can recommend someone else that does?

The fuses were blown and he never tried to power it on.
The 2n2905 on the power supply gets insanely hot.
8080 cpu had multiple legs corroded off. View attachment 726245
that golden broken legged 8080 is worth $100 all day long on the bay.
 
I've seen legs rot on both gold and regular leads. After cleaning the legs are left if there is some of the original pin exposed you can solder on a new pin. I kept some dead EPROM chips just for the leads when I need some. Just recently had to fix some mask ROM's that way.

Chances are high that you'll need to replace the DIP sockets on that main MPU board and probably the four 10uf electrolytic caps too.
There is no reason to clean gold legs. Gold is noble and doesn't corrode.
 
There is no reason to clean gold legs. Gold is noble and doesn't corrode.
Gold doesn't corrode. But if you have a dirty environment you can get stuff deposited on pure gold. Dirt, nicotine, lime scale, battery acid and its secondary effects, etc. You should still inspect gold pins and clean them as needed.
 
Gold doesn't corrode. But if you have a dirty environment you can get stuff deposited on pure gold. Dirt, nicotine, lime scale, battery acid and its secondary effects, etc. You should still inspect gold pins and clean them as needed.
I cannot disagree with your assertion. However, the cleaner should fit the problem.

Don't sand gold contacts. Don't clean them with crocus cloth, or emery paper. It's a very thin layer of gold.

If you remove it, now you have a problem

So clean for the grime. Don't sand them down to tin.
 
Who mentioned or suggested sanding contacts? I don't see where that was discussed. Just that the chip leads should be cleaned. You use whatever methods are appropriate to the ones you are working on.

I don't sand any of the chip leads. I've had the best luck lately using some of the small round scotch bright pads meant for a Dremel motor tool. Just make sure the rotation is with the direction of the leads or disaster will strike. They come in a variety of grits and have done a great job for me. Typically are doing that on other chips without gold leads. But I have had to solder on replacement leads for chips with both regular and gold leads.
 
Who mentioned or suggested sanding contacts? I don't see where that was discussed. Just that the chip leads should be cleaned. You use whatever methods are appropriate to the ones you are working on.

I don't sand any of the chip leads. I've had the best luck lately using some of the small round scotch bright pads meant for a Dremel motor tool. Just make sure the rotation is with the direction of the leads or disaster will strike. They come in a variety of grits and have done a great job for me. Typically are doing that on other chips without gold leads. But I have had to solder on replacement leads for chips with both regular and gold leads.
I'm not saying you (or anyone) did say that.

As a NACE Corrosion Specialist, I'm just laying out some concepts so that those who read this go the right way, not the wrong way.
 
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