Mailist to discuss all issues regarding the Digitech GSP-2101 Guitar FX Processor

Here is what I have found. I have 2 sets of EPROMs 2.01.00 and 
3.0.0a. When I put them in my EPROM burner and read them, the 3.0.0 
ones are readable but it looks like they have been psuedo-erased. The 
2.01.00 ones read great, I was able to save their images also. The 
older eproms should work when I pull the PPC, the unit still will not 
boot up. I suspect that somehow (maybe some kind of ESD) screwed up 
these eproms, and even the memory (which I am having difficulty 
sourcing) the 2101 memories have an extra CS line, and are 70 ns or 
better. The RAM I bought (through Mouser) has built in battery 
backup, but not the extra CS, so I suspect that the RAM could be bad 
also. Anyone have the 3.00 eprom images? Since I already own the 
chips, passing me the images is completely legal, I will erase and re-
burn them.


--- In gsp-2101@yahoogroups.com, "wulffert" <mark@w...> wrote:
> Well, if I can't fix it, I will at least sell it for parts. It is
> looking more and more like a memory access problem, once I get some
> new parts in to swap out I will know. Could also be a bad decoder
> chip, the logic analyzer shows no memory reads or writes occuring, 
the
> Z180 boots up, trys the ram then gets stuck reading the eprom. Any
> Z180 programmers out there?
> 
> --- In gsp-2101@yahoogroups.com, Adrian Teo <adrian.teo@a...> wrote:
> > I'll buy it off ya! :)
> > 
> > -AT
> > 
> > 
> > > -----Original Message-----
> > > From: wulffert [mailto:mark@w...]
> > > Sent: Friday, August 20, 2004 7:57 AM
> > > To: gsp-2101@yahoogroups.com
> > > Subject: [gsp-2101] GSP-2101 processor problem
> > > 
> > > 
> > > I have working on my 2101 for several months on and off so far. 
I 
> > > have v3.00 with the PPC installed (both are SDISC II). It has 
the 20 
> > > MHz crystal with 10 MHz Zilog (even though schematic calls for 
> > > hitachi). This unit one day decided to blow fuses (it only does 
this 
> > > sporadically), turns out the current draw is at the threshold, 
I put 
> > > a slightly larger fuse (I know a big no - no) but unit turns on 
and 
> > > nothing gets hot, so other than a slightly elevated current, I 
can't 
> > > find any shorted parts. Nothing works, front panel is all 8 8 8 
and 
> > > blocks on the LCD. No communication with foot controller. Looks 
like 
> > > processor is running, I see acivity on address and data busses, 
on 
> > > all lines. I never see the CS line go low to the memory, 
although it 
> > > may at startup. Decoder chips seem to be ok. Anybody seen this 
before?
> > > I even tried the old V2.02 firmware, pulling the battery, 
factory 
> > > reset.
> > > 
> > > Mark 
> > > 
> > > 
> > > 
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> > >