How hot should chips be on a PCB?

GoneMad

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I just started some trouble shooting on my double dragon.I will not boot up at all. Has all good voltage so when it was on, for shits and giggles, I felt a few of the chips on the front board. The first 3 in the row of 7 next to the ribbon cable were warm and the other 4 were cold. The large removable chip in the center of the board was so hot I could not touch it for any more than a second. Is this normal for some of these chips?
 
Too hot to touch is usually a bad sign, what are the markings on the chip?

In general....

PAL/GAL chips run borderline hot
74ls240s and 245s run warm
Z80s and 68000 CPUs are slightly warm after ten mins.
The rest of the common chips hardly put out heat at all.
 
Too hot to touch is usually a bad sign, what are the markings on the chip?

In general....

PAL/GAL chips run borderline hot
74ls240s and 245s run warm
Z80s and 68000 CPUs are slightly warm after ten mins.
The rest of the common chips hardly put out heat at all.

It's a 40 pin. The markings are
MC6809EP
T6R8117
 
Thats a 6809 CPU, it should be slightly warm to the touch, if it is stinking hot it is bad. Is it in the socket the right way round?
 
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Some chips have heat sink glued right on top of them. My Ms Pac has about 4-5 with heat sinks on them. Like you observed though, some get warm, other don't.
 
Thats a 6809 CPU, it should be slightly warm to the touch, if it is stinking hot it is bad. Is it in the socket the right way round?

Sorry to be picky, but that's a 6809E CPU. It's different from the 6809, but still should only be warm to the touch.

The E signifies external clock and it doesn't have the ability to drive a crystal directly. You can't swap the 2... E fits a board designed for an E and the plain fits a board designed for the plain.

RJ
 
I double checked again this morning and a bit more than "warm to the touch". After having the game for about 2 minutes, it was getting very uncomfartable to hold the back of your finger to it for any more than about 5 seconds. If it's bad, would there be something to cuase it to go or just die on itself?
 
The most likely cause is that someone has been trying to fix the board and has put the chip back the wrong way round. If it is still reversed then it is 99% likely to be dead, if it is in the correct way round now then it is 100% dead.

Having said that I have met one board with a Z80 on it that was doing the same thing and that was soldered to the board so could not have been reversed, there wasn't much else wrong with the board so I don't suspect the board had it is power applied incorrectly.
 
I only have a few games to check to see if one would have another chip the same, but my Robocop and Commando seem to be different. I,m not gonna mess with R-type. I finally got it working well. I do have another double dragon coming in the mail, whenever that will arrive, so I guess I will wait for that to get here. I bought it untested so not sure what to expect. It may or may not work. Hurry up and wait. Not much else to do.


Doug
 
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