--- On Tue, 16/3/10, Jack Pratt wrote:
From: Jack Pratt
Subject: Re: [xl7] Re: HELP: FX RAM failed error
To: xl7@yahoogroups.com
Date: Tuesday, 16 March, 2010, 20:15
Hey steve.If the P2500 mother board is identical to an XL7 motherboard (I suspect so, but...) FX RAM is the SOJ28 (the one with missing central pins) package to the front left of the motherboard - U35; right next to the ROM slots. This is not memory used by the microcontroller (which is towards the right and back on the motherboard in a TSOP 54 package).The FX RAM (81C4256 = 256kBit) is used to produce a pipeline by the large IC next to it "IC405" (U34) for sound effects (not the FX bus) so that you'll probably find that any sound that has any effect (eg chorus) will be bad.It is unusual that a DRAM would fail, but if you have access to a hot air solder rework station you could try reworking the solder joints (which may have become dry). You also need to consider the bypass capacitors next to it and solder joints on U34 (with which it communicates). If the DRAM has not failed (and its not just a dry joint or two) then U34 could be failing which means that you're unlikely to ever get good sound out of the thing wihtout stipping all effects [making the sound output very bland].If you are not competent to do the rework yourself, then you probably need to find someone who is to avoid damage to your unit [not something you should attack if the soldering iron is not your friend].Unfortuantely 81C256's are not common at all these days, and the package makes removal a challenge without a solder rework station [and then its trivial]. So if you wanted to try replacing it...
From: steve_the_composer
To: xl7@yahoogroups.com
Sent: Tue, March 16, 2010 7:31:21 PM
Subject: [xl7] Re: HELP: FX RAM failed error
Footnotes:
(1) Since only the main outs are connected to the FX system, I suppose I could always use it was a non-FX E-Mu/sequencer/ controller using the sub outs. Still, it would be nice to have the FX working.
(2) Putting FX into bypass mode does not get rid of the noise.
--- In xl7@yahoogroups. com, "steve_the_composer " wrote:
>
> Does anyone have a solution for an FX RAM failed error?
>
> I have a backup P2500 that hasn't been used in several years. It used to work flawlessley. However, when I went to test it, there was an awful noise coming through the headphones. Everything testable in diagnostics passes, except FX RAM. I cannot imagine it would would have failed from lack of being used, but who knows. Any thoughts, suggestions? Is it possible to replace the FX RAM? If so, how? Thanks.
>
> --Steve
>