Quoted from Mitch:
Where did you get the replacement chip. Most nvram chips I've seen all say ramtron.
Yes, because it's a NVRAM (non volatile) and the Ramtron brand is specialized in this technology, but the original RAM is a basic 6264 Static RAM (CMOS). There is ton of manufacturers for the 6264. Original are from SHARP, but any other brand will fit nice.
Quoted from johnwest80:
I got it from action pinball. It’s their 6264 part #. Are there some that work better than others?
There is nothing weird here, they provided a memory from Alliance, which is a well-known manufacturer.
The original component is a LH5164-10, pinout and electrically compatible with 6264, having an access time of 100 ns. The component provide by Action Pinball is an AS6C6264-70, functionally identical, having an access time of 70 ns. So, it should work !
Unfortunately, it is becoming more and more common: sometimes new components do not work.
Myself, I've recently bought a batch of RIOT 6532 where about 40% were (partially) defective. And even worse with a 6821 batch, with 60% of default. And this is not a problem from China market ! this affect all countries, and even serious sellers can sell defective lots without knowing it.
I became very suspicious and now, I test all my components before using them.
If you have an EPROM programmer, usually, it include a test mode for basic components (TTL, CMOS and SRAM). Not all, but most of them have this feature.
I have been doing electronics for almost 40 years and we do not expect to come across faulty components when we buy new ones. But I think that today, we can no longer trust blindly, it is imperative to check its components before using them.