Dm74s287an

XianXi

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(256 x 4) 1024-BIT TTL PROM

Can this be read as a 74XX287?

Fixing a PCB that has 3 of these for the RGB output and they all run at about 120 degrees F after about 10 minutes the video drops out then once it cools the video comes back.
 
That's a N82S129 sub, there are many part numbers that sub these. If your just wanting to read it you should be fine setting your programmer on N82S129. As far as programming one you need the setting for the exact PN your programming to guarantee results.
http://www.twistywristarcade.com/bi-polar-proms/786-hm-3-7611-n82s129.html
It is normal for proms to run very hot to the touch.
 
Go pick up a can of "air", turn it upside down, and spray the chips to see if cooling them down brings the video back...

Or, even better would be to check the input pins and the enable pins on the PROMs with your logic probe to see if they have activity before you pronounce the chips bad. It could simply be that they are losing their input and/or control signals which is affecting the data they output. ;)

This only works if the game is still playing "blind" - if the CPU is locking up then the output PROMs aren't the problem.

As for the PROMs, you can read 'em as some other supported chip by your programmer as long as the pinouts and enable pins are the same. (Some enable pins are active high vs. active low so double check!)

You can't always program the PROMs the same if they have the same pinout. Some manufacturers created PROMs that are all "00" (logic zeros) when blank and others are all "FF" (logic ones) when blank. There are also different programming algorithms - voltage levels, pulse length, pins active when programming, etc. - and these algorithms must be compatible before you can program one part # PROM by telling your programmer it's a different one.

RJ
 
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This IC is set to all low from the factory and altered from the paired ICs according to the datasheet.

It plays blind when it gets too hot, so the CPU isn't locking up. I'll try placing a heatsink on them to see what happens and probe them before hand to see if the inputs are getting lost.
 
It was a Terra Cresta. Everything else was fixed about the board but just wondered about that aspect of it as I own one myself.
 
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