Emax

In response:
"I've never seen an IC kind of work.”

I would hazard to say you’ve never worked in electronics repair industry then. 
In 16yrs experience I certainly have. Thats where the term “flaky” came from. Intermittent and often not easily explainable faults…
NTE had a reputation for making semiconductors in the 80s and 90s that would easily fail as their new parts spec didn’t hold up over time or was lower than the OEM part, even though their cross ref said it was an equivalent part.
If there was any way to get another brand quickly and NOT use NTE, we would do it.
I can’t say whether that’s true now. But that is why I buy from mouser and digi-key and avoid buying from the local shop.
Much as I like the staff there, NTE is not my goto brand and that’s what they stock… cuz it’s cheap.

But remember that there is a MTBF # hours on any part.
EPROMS 20yrs old can lose their programming and fail. It’s not unheard of…. In point of fact- 10 yr old EPROMs in Pinball machines could fail if the AC fan in the cabinet failed and the board ran hot all the time. As heat over time affects semiconductors.
This is probably less prevalent today, as electronics tech is much more robust than it was 20-30 yrs ago.

One or two people copied the Emax parameter EPROM and put in the copy into their machine and it worked.
But I tried it some time back and it didn’t work for me.
So I don’t think it’s as simple as all that.
Maybe the challenge code for some batches of machines was the same, so if you had two machines in a short serial number sequence or maybe the exact same rev EPROM, they would have the same challenge code, but one with different rev EPROM and or serial grouping would end up with a different code.

There isn’t enough data available to make a determination on that. 


-T





On Feb 7, 2016, at 12:42 PM, midipuppies@... [emax] <emax@yahoogroups.com> wrote:

I fully understand the adjust features element. I upgraded my original Emax II over the phone with E-mu in 1992.


I was under the impression that inserting the 8MB binary into that EEPROM is the same as what the keyboard would do if the correct adjust features code was put in. Is it possible that the chip itself is not working properly? I've never seen an IC kind of work.





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