Replace SRAM with faster/slower? Duplicating bios flash...

[Barry Klein]

I am repairing an Alesis A6 Andromeda music synth. It has a (common) problem where it boots to the "splash screen" but doesn't come all the way up and work. The problem is almost always fixed by swapping out the main pcb (CPU board). Now main boards are all used up. The board uses a Coldfire 90Mhz MCF3507 chip. I replaced it and the board works the same. I replaced the NVRAM part and still the same. Replaced the two SRAM chips with the correct and same part numbers and now two diagnostic/firmware load modes no longer work. I can solder the originals back but the service manual states a problem with another manufacturer's SRAM with these symptoms. So I am wondering, Should I try swapping these two chips with others that are faster or slower? These were 15ns parts.

Also I am thinking of removing the bios flash and writing its image to a new part. Should this work? When things with the original SRAM were sort of working I could load code to the synth via sysx file and it would start to write the flash but hang on a block verify.

 

[(*steve*)]

Typically you would replace with a faster part of you can't get a slow enough replacement

Oh, the original marking -15 probably means 150ns.

 

[Barry Klein]

no its nS.
This synth has been a challenge. I found a weak flash CS via that put all my testing of parts at risk.
I have to backstep on testing SRAM parts as well as really suspect bad flash programming at this point.
Explains why replacing with 15nS and 12nS didn't work and now the original parts don't either.
Thanks.

 

[davenn]

no its nS.

no, it's ns. ns = nanoseconds

"A nanosecond (ns) is an SI unit of time equal to one billionth of a second, that is, ¹⁄₁ ₀₀₀ ₀₀₀ ₀₀₀ of a second, or 10⁻⁹ seconds.
The term combines the prefix nano- with the basic unit for one-sixtieth of a minute."

 

[(*steve*)]

Yeah, nS is nano-Siemens

And that's a derived unit equivalent to kg⁻¹⋅m⁻²⋅s³⋅A²

 

[Harald Kapp]

no, it's ns. ns = nanoseconds

@davenn : It took you 5 years to figure that out?

 

[davenn]

@davenn : It took you 5 years to figure that out?

it came up as a new post, some how. in the new posts list
else I would never have responded