thoughts on Digitech Space Station eprom copying?

[Processaurus]

A local friend got a space station recently up here and I must admit it is actually a really cool, strange pedal, unfortunately they go for $300+ used, so I was wondering if anyone here knew what it would take to copy the chip off my friends and put it in a cheaper pedal from that XP series, like the modulator or whammy/wah, or reberberator, whichever is the cheapest.  There are reports of a guy copying it, and also someone who puts all 4 of the eproms in one pedal with a rotary switch to select the model.



Thanks for any thoughts on this, I may even have a suitable programmer at my work...

[slacker]

Don't know if it's any help but I remembered that something similar had been discussed before. http://www.diystompboxes.com/smfforum/index.php?topic=35600.0

[swt]

you should contact maneco. He's got the program of all xp series, plus can program the chip for you, and upgrade from xp100 to 300 if you have the pedal...

[Processaurus]

Maneco eh?  I'll pick his brain, once I get my hands on a modulator, hopefully its something I can do in house, I understand it may need some extra RAM soldered in, luckily I can refer to a real space station when converting it.  What would totally cool and out of my league is to mix the patches from the different models!

[joelap]

IF anyone is interested in giving this a shot, I'll gladly help out any way I can.  I had thought about compying the Eprom of a WH-1 whammy to just get a peak at the programming out of curiousity, and IIRC the XP-100 and WH-1 have the same programming.  I'd be willing to shell out some dollars for a way to connect my PC to the chip, assuming its not too expensive.

[Processaurus]

No luck getting ahold of Maneco, but i got ahold of a Modulator and Reverberator.  They are indeed the same PCB.  The Reverberator comes with 3x  NEC 41464 DRAM chips
(same chip as the DD-2 and DD-3), and an empty 4th socket, and the modulator comes with one DRAM chip, and no sockets in the extra positions (which are filled with solder, so it would be a little chore desoldering them and installing the sockets.    We just happened to have a suitable programmer hooked up to the PC at my work (shows how much I know about this stuff), I could read the 27c256 eprom and store it on the computer ( MUUUHAHAHA!), but all we had around were these 27c512 eproms, which gave me an error when programming them.  I got some 27c256s coming in the mail sometime, I guess I'll wait til they get here.

Incidentally the obsolete NEC DRAM is really hard to find, I'm going to try a substitute 64K x 4bit, 100ns DRAM chip, we'll see if it works out.

On a non digital side note, I wonder if there is anything that can be done about the taper feel of the rocker control, the action is all bunched up in the middle.  Any ideas?

[Processaurus]

Its Aaalive!  Pretty cool, huh?  I thought I would have wait for parts, but I stole the eprom and DRAM out of the modulator, and copied my bro's space station eprom, it didn't work at first, I think because the reverberator and modulator were missing some parts, compared to the space station:
C65, C60, and C61 = 10uF 16v tant
R31 = 4.7K, 805 size (surface mount)
[EDIT]  the modulator was missing u13, an mc34064 undervoltage reset goodie.
All my fiddling with it must have corrupted something on the eprom the first time, I was totally confused why it wasn't working, tried the newly space stationized eprom in the real space station, it didn't do nothing, I briefly envisioned the conversation breaking the news to my friend that I had killed his new space station.  But then I erased it and tried it again,  this time with a label on it from the get go, and ta da!  I was worried that the DRAM in the reverberator and modulator was too slow, it is the 100ns kind, and the stuff in the space station is 80ns, but it works fine with the 100ns DRAM, soo...  Such a weird pedal...  my favorite right now is the setting that when you play something, after an amount of time (short or long) it comes back backwards, its better than other reverse delays, because the seam in the blocks of reversed playback is right on the beginning of your note, every time.  That sounds confusing, i'm sure.  So is this pedal.

Oh, it was fun desoldering the filled in empty socket holes in the modulator, I used the heat gun to heat up the whole section, and then smacked the board on the trash can, flying solder galore!

[Processaurus]

Eeeek! I procured an xp100 whammy/wah to space stationize it and hawk to a friend who needs space station in their life, thereby enhancing local music, but it doesn't have any eprom or socket or anything in sight.  It must be the newer version of the xp100.  Looked like a pain to figure out everything to change around, and now I remember reading something the Jetpack mods guy said that they were a pain to mod, so I guess that's that, mattress man.

[Processaurus]

People complain about the bypass on these.  It would be fine (it uses FET switching and an opamp buffer, no monkey business like leaving the DSP engaged) except it has a gain control on the input that is used to get a good level for the A/D converter.  Unfortunately they did nothing to attenuate that gain back down to the original level.  So it gives a pretty hot signal to whatever is after it, which will change how an amp reacts.  On one of mine I stuck a dual pot on the two outputs as a volume control, works well.  I can't tell the difference between it and my true bypass loop.

What would be ideal, and digitech should have been on this, would be to use a pot to simultaneously turn the output down as the input gain goes up, or use a rotary switch or something instead, to keep things at unity.

[Jaicen_solo]

I just rediscovered this thread, and it's got me all  excited again!

Processaurus, do you think there's any chance you could sort me out a brief tutorial on what you did, and also possibly a new EPROM so I can convery my XP100??

[clayton9610]

I would love to be able to upgrade my xp100 eprom.If only I could find an xp300 eprom copy

[Processaurus]

Just found this picture, it is of the modded Modulator pedal, the toggle switch there is the chip enable switch, to decide whether it boots up as the whammy or space station.  It doesn't have the whammy eprom in its piggybacked socket, yet, in the photo.

[Paradroid]

It would be fine (it uses FET switching and an opamp buffer, no monkey business like leaving the DSP engaged) except it has a gain control on the input that is used to get a good level for the A/D converter.  Unfortunately they did nothing to attenuate that gain back down to the original level.  So it gives a pretty hot signal to whatever is after it, which will change how an amp reacts.  On one of mine I stuck a dual pot on the two outputs as a volume control, works well.

Sorry, I know that this is an old thread but I have this very problem with my own Space Station: I love the wild sounds it makes but sorting out the levels is a real problem. Setting the input too low means that the FX don't work as they should yet when the input is set correctly the resulting high output creates other problems down the line.

Processaurus, can you please provide details on exactly what kind of dual pot you used i.e. what was it rated? Also, I'd be interested to know where you mounted the pot on the unit. Any photos would be a real bonus!

Thanks for your help.

[Processaurus]

I just used a dual 10K (audio taper) pot, cutting the traces with an xacto knife to the L & R output jacks and inserting the pot in between:

before:
---------------------------- jack tip connection

after:

             cut
 --------o----X---o----- jack tip connection
         |        |
         |        |
        .-.       |
        | |<------'
   10K  | |
        '-'
         |
        GND


(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

I don't have the pedal here to take a picture, but I wanted the pot not to get bumped, so I cut the shaft mostly off, leaving about 1/8" out of the threaded collar, and hacksawed a slot in in the end so it could be adjusted with a screwdriver or fingernail.  The hole for it was in the plastic side piece, under the top ledge.  I used shielded wire because I was paranoid about noise.   You could use mic cable (the hot to the pot, the cold from the wiper to the jack, shield connected to pot ground and pedal ground) for that.

Another place to stick your control is under the rocker pedal, it is safe and quiet (and usually dusty) under there.  That's where that funky light green toggle switch in my photo is.  One of small bear's 16mm dual gang pots would fit there.                 
                                                         

[Jaicen_solo]

So any idea where I can source a copy of the SpaceStation EPROM?

[Paradroid]

I just used a dual 10K (audio taper) pot, cutting the traces with an xacto knife to the L & R output jacks and inserting the pot in between.

Thanks so much for the speedy and informative reply! Really helpful information! I'm going to open up my unit tonight and start planning where the output level control pot will go. Under the rocker pedal sounds good (if it will fit).

Out of interest, do you know what value the stock input gain pot is?

[Paradroid]

Out of interest, do you know what value the stock input gain pot is?

Answered my own question by opening up the Space Station and having a look: the pot says "W100K". Mixed information about that one on Google...

[Processaurus]

Schematic for the XP series, analog section is on page 2:
http://experimentalistsanonymous.com/diy/Schematics/Vibrato%20and%20Pitch%20Shift/Digitech%20XP100.pdf

[Paradroid]

Schematic for the XP series

Great! Thanks again for the help!

I've soldered in an output control to my Space Station and it's SO much more enjoyable now! I can feed the effect a healthy level without having the output result in a massive boost to my signal. Much better! Nice to finally be able to tame the this wonderful sonic manipulator and not have it overload everything further down the line.

Since you seem to know the unit pretty well, I'll ask another question: are you aware of any points on the mainboard where I could get a DC voltage suitable for powering an LED? It seems the schematic gives some clues but, at my skill level, it would take me a very long time to work out how the schematic relates to the physical circuit.

[Paradroid]

Well, I finally completed my mods!

My Space Station now has a nice big output control next to the stock input control. I also installed a true bypass footswitch and red LED indicator to show when the unit is bypassed. The true bypass only works on the left channel (the right channel gets the stock Space Station bypass) but that suits me since I don't use the unit in stereo.

Having the true bypass is really useful for level matching since I can switch the unit in and out while adjusting the output level, carefully comparing the output. Without the bypass it's really hard to setup unity gain.

Of course, the levels of the actual effects vary quite a bit but with a unit as simple and quirky as this you have to roll with what you get. At least now my unit is setup not to boost the overall level and can be taken out of my chain completely when not in use.

I installed the 3PDT switch in between the 2 black footswitches on the unit. If I could do it all again I'd probably wouldn't have centered the 3PDT since it sticks right out of the unit and makes it trickier to press the stock switches with your foot. The 3PDT stands so high because of the wedge shape of the case: it's not deep enough to lower the switch down.

Overall, I guess I'm done with modding this pedal... unless someone comes up with a step-by-step guide for adding the other XP EPROMS.