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

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

Sometimes, if the source of AC doesn't have enough wattage
can cause the problems. Did you try connecting the unit in
a different location?
--- wulffert <mark@...> wrote:

> 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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-AT

> -----Original Message-----
> From: wulffert [mailto:mark@...]
> 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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>

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 
> > 
> > 
> > 
> > ------------------------ Yahoo! Groups Sponsor 
> > --------------------~--> 
> > Create your own customized LAUNCHcast Internet Radio station. 
> > Rate your favorite Artists, Albums, and Songs. Skip songs. Click here!
> > http://us.click.yahoo.com/5ddjqC/xA5HAA/n1hLAA/XkLolB/TM
> > --------------------------------------------------------------
> > ------~-> 
> > 
> >  
> > Yahoo! Groups Links
> > 
> > 
> > 
> >  
> > 
> >

anyone have a clue what they charge?

On Sat, 2004-08-21 at 14:55, Graham Pearson wrote:
> DigiTech is still willing to repair GSP-2101s.  Why don't you send it
> back to them?
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>         Service.
>

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 
> > > 
> > > 
> > > 
> > > ------------------------ Yahoo! Groups Sponsor 
> > > --------------------~--> 
> > > Create your own customized LAUNCHcast Internet Radio station. 
> > > Rate your favorite Artists, Albums, and Songs. Skip songs. 
Click here!

> > > http://us.click.yahoo.com/5ddjqC/xA5HAA/n1hLAA/XkLolB/TM
> > > --------------------------------------------------------------
> > > ------~-> 
> > > 
> > >  
> > > Yahoo! Groups Links
> > > 
> > > 
> > > 
> > >  
> > > 
> > >

After replacing the EPROMS and the RAM, the unit is up and running. 
It looks like the SDISC chips are fried also, there are no effects 
and I can only use bypass. I did some signal tracing and verified 
that the SDISC chips are both gone. My 2101 was loaned to a friend, I 
think he fried it, some kind of power surge (so he says). Ironically 
the Zilog chip is fine. Anyone know what the difference is between 
SDISC I and II chips are? I have the SDISC II ones.

Incidentally, I am using a Dallas 1245Y ram module, and I did a mod 
to the battery backup circuit (battery is no longer needed because 
the 1245y has it built in)

This teaches the lesson not to loan people items that are important to you. Only loan things that can be easily and cheaply replaced. My brother had a video camera that I loaned to some friends. They returned it and we didn't use it for over 6 months after that. When we took it out it didn't work. It turned out they used it near a pool. Water probably got in somehow. Hopefully it doesn't turn out your friend now has a GSP2101 also. He could have bought it damaged for real cheap and used your unit to fix it. Also, some people just like to open up stuff to see how it works. That's ok with his own stuff but not when it's someone else's stuff. Don't immediately take either to be the case. It could really have been an electrical surge but I think either way, he was irresponsible with your unit either by leaving accesible to damage or by not paying for the damage even if it was not his fault. If he's broke then I know he can't pay.

wulffert <mark@...> wrote:
After replacing the EPROMS and the RAM, the unit is up and running. 
It looks like the SDISC chips are fried also, there are no effects 
and I can only use bypass. I did some signal tracing and verified 
that the SDISC chips are both gone. My 2101 was loaned to a friend, I 
think he fried it, some kind of power surge (so he says). Ironically 
the Zilog chip is fine. Anyone know what the difference is between 
SDISC I and II chips are? I have the SDISC II ones.

Incidentally, I am using a Dallas 1245Y ram module, and I did a mod 
to the battery backup circuit (battery is no longer needed because 
the 1245y has it built in)


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