Space Invaders Clocks @ C7 (74LS160 issues)

Scucci

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I'm trying to get a Midway (L) Space Invaders set back up and running. I started with gibberish on the screen... Eventually found that C7 (9310/74160) was bad and missing 2 signals out (pins 13 and 11 IIRC). I didn't have a 74160 so I bought a couple of 74LS160s. Now I'm getting good clock signals on every pin except for 13... it should be 2MHz, but it flutters between 3.3MHz and 5MHz. I tried both of the LS160s and they both behave the same, even with the pin lifted out of the socket.

Is a 74LS160 not fast enough? I'm checking before I order 74160/9310s since they aren't exactly giving those away (looking at eBay).
 
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... so I bought a couple of 74LS160s. Now I'm getting good clock signals on every pin except for 13... it should be 2MHz, but it flutters between 3.3MHz and 5MHz. I tried both of the LS161s and they both behave the same, even with the pin lifted out of the socket.
Are you using LS160's or LS161's? Both have same pinout, one is a BCD and the other is a Binary counter - incorrect one will produce a different output frequency.

 
Are you using LS160's or LS161's? Both have same pinout, one is a BCD and the other is a Binary counter - incorrect one will produce a different output frequency.

I'm using LS160s
 
I'm using LS160s
I only asked because you mentioned both and those keys are not normally next to each other to be a typo.

Maybe check all the Pads and tracks on both sides of the socket. You might have a hairline bridge or open on a trace between some pads causing it to do strange things.
 
I only asked because you mentioned both and those keys are not normally next to each other to be a typo.

Maybe check all the Pads and tracks on both sides of the socket. You might have a hairline bridge or open on a trace between some pads causing it to do strange things.
Typo... I had to go back and re-re-read the original post. Guess I fat thumbed the "1" instead of the "0" (I use the number pad most of the time). Fixed the typo.

Verified no bridges or anything like that... just acting wonky.
 
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