Z80 blown, slower in place of a faster chip?

ifkz

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As a side project during my Zero Team PCB fixes, I got a POW board yesterday. It appears the Z80 on it is blown, it is 6Mhz type. I only have 4Mhz chips on my parts boards, will these work, or not???
 
This POW? According to MAWS, the Z80 in this game only runs at 4Mhz anyway, so you should be fine. Probably someone just happened to only have 6Mhz parts on hand when trying to repair it themselves. Which begs the question, what's killing the Z80?
 
Check to make sure it is inserted the correct way. Don't just insert it the way the old one was. I get boards with upside down CPUs all the time. They generally don't like that.

Also regarding the CPU speeds. Contrary to popular belief, there is not a specific chip line cranking out 6MHz parts and a chip line cranking out 4MHz parts. There is one line. If they need 1000 6MHz parts they test the chips until they get 1000 that pass the tests at 6MHz. The ones that don't pass get thrown back to be tested at a slower speed and the ones that didn't get tested may work at 6MHz. The rated speed for chips means that they passed at least the speed they were tested at, it doesn't always mean the maximum speed the chip can do.

ken
 
Thanks, the chip is actually soldered into the board, so I have a little work ahead of me. It will get a socket so I can easily test things out.
 
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