thoughts on Digitech Space Station eprom copying?

[digi2t]

I ordered the A1M dual-gang pot from Small Bear Electronics but neither of the knobs I bought (1 for the 6P4T, 1 for the A1M) fit the shaft. I emailed Small Bear for knob dimensions for the A1M.

The switch shaft is 1/4" splined. I used the pot from Tayda, which is also splined. In both cases, I used these knobs;



You'll just have to shorten the length of the switch shaft to get the knob to sit all the way down. If you pot shaft is not splined (smooth), then a knob with set screw will be required.

I also just ordered the 32-pin and 3x 18-pin sockets from All Electronics... they were labeled "IC socket" so I will assume for now they will work, but like I said, I didn't know the pin spacing for the RAM, EPROM chips so it was kind of a shot in the dark. I assume it's a standard size, though. Still waiting for those chips to arrive from eBay.

EPROM sockets; http://www.westfloridacomponents.com/SK044APH01/view.html
SRAM sockets; http://www.westfloridacomponents.com/SK018PF02/18+Pin+IC+Socket+DIP+Open.html
Pitch and pin spacings are listed in both cases.

Does the perf board need to have pads on both sides or just one? I was a little confused from the tutorial.

http://www.ebay.ca/itm/PCB-board-double-sided-prototyping-PCB-board-4-SMD-part-/220330242967?pt=LH_DefaultDomain_0&hash=item334cb4b397

Thru holes, with pads on both sides. If in doubt, use vero.

[pk1802]

I'm getting geared up to do the full monty. I bought a xp100 on ebay, and it arrived to me with the w100k pot on it broken(hopefully that is the only problem).

I'm having a hard time trying to find that part anywhere online. Does anyone know where I might be able to find one?

It looks like a 12mm pot with a D shaft, but I'm not sure how long the shaft is.

[Govmnt_Lacky]

@pk1802

I have some replacement pots. PM me and we will work something out.

Cheers and Happy New Year!

[pedalmaker]

Hey guys,
I have almost everything to do this mod, except the chip. How can I get the preset data on the chip? Can someone here do this for me for a fee? I would be wanting to do the XP-ALL. 

[Govmnt_Lacky]

Hey guys,
I have almost everything to do this mod, except the chip. How can I get the preset data on the chip? Can someone here do this for me for a fee? I would be wanting to do the XP-ALL. 

If you want an XP ALL then you are going to need (3 to 4) 27C256 chips. You will need to have them erased and then each one loaded with the appropriate program. What pedal are you planning to mod?

Unless you want to use the 27C1001 chip which can have all of the programs on 1 chip.

I recommend you try contacting Dino (digi2t) and see if he can hook you up. I would but, I only have 1 set of chips left for a mod I need to do 

[digi2t]

I don't supply chips. I can however provide the required specs/suppliers info, and you can buy the chips yourself. You may then send them to me for erasing and programming. I test all chips in my unit before shipping. I only charge for the return postage, which is generally $5 U.S. for North American destinations. $9 for the rest of the world.

This is my modis operandi insofar a programming 27C256, or 27C1001, for others is concerned.

PM me for more info.

[SISKO]

Does any one know if the 4464 DRAM would work on this project? Its listed on this schematic http://experimentalistsanonymous.com/diy/Schematics/Vibrato%20and%20Pitch%20Shift/Digitech%20XP100.pdf
The thing gas I was looking for 41464 all over the place but could not finde them.

[digi2t]

Does any one know if the 4464 DRAM would work on this project? Its listed on this schematic http://experimentalistsanonymous.com/diy/Schematics/Vibrato%20and%20Pitch%20Shift/Digitech%20XP100.pdf
The thing gas I was looking for 41464 all over the place but could not finde them.

I found lots on eBay. That's where I got mine from, but avoid seller G&C (Good and Cheap). I bought from there, and they turned out to be duds. Sellers that I have bought good chips from eBay are;
ACP Surplus (U.S. supplier)
U-Barn (Hong-Kong)

I'm sure G_L can chirp in here as well. He's done a few conversions.

[SISKO]

Ill buy them from a local store. Its a "serious" one but before I buy them, I need to know if the 4464 would be replacement for the 41464 DRAM that everyone seems to use around here.

[Govmnt_Lacky]

I need to know if the 4464 would be replacement for the 41464 DRAM that everyone seems to use around here.

Could you provide the complete part number?

I have only found one good replacement for the UPD41464C-10 RAM that comes in the XPs and they are the same prices as the original parts.

If you are referring to the part number called out in the Digitech schematic (4464), I believe that was just a number for in-house referencing. If you want the stock part number, it is UPD41464C-10.

[SISKO]

The complete part number is TMS4464-10

This are the only "datasheets" I could find:


More here:
http://www.ucontrol.com.ar/forosmf/explicaciones-y-consultas-tecnicas/hoja-de-datos-del-chip-tms-4464-10nl-de-texas-(memoria)/?action=dlattach;attach=7914
And here:
http://www.ucontrol.com.ar/forosmf/explicaciones-y-consultas-tecnicas/hoja-de-datos-del-chip-tms-4464-10nl-de-texas-(memoria)/?action=dlattach;attach=7916
and:
http://www.ucontrol.com.ar/forosmf/explicaciones-y-consultas-tecnicas/hoja-de-datos-del-chip-tms-4464-10nl-de-texas-(memoria)/?action=dlattach;attach=7918

Its seems to be pin to pin compatible with the D41464 memory.

The BOM on the XP100 schematic calls for (Quan   Reference   Part   SYMAN   Description)
1   U19   4464-100   72-3149-10   4464, 64K X 4 Dynamic RAM -100ns LH2464

Should I try?

[digi2t]

I've looked at the datasheets, read some Commodore (remember those?) memory upgrade posts, and picked out the following quotes;

I'm not using 4164's I'm using M41464 produced by OKI
compatible chips are
OKI M41464 Samsung KM41464AP Texas Instruments TMS 4464 Toshiba TMM41464AP NEC 41464C

Early C64 computers have eight 4164 TTL RAM chips installed.
Some interim brown case and all later OEM C64C (white case)
computers have only two 4464 RAM ICs (41464 is the same IC) as
those chips have four times the memory "density" of the 4164.

But then, I fell on to an Atari forum, where lo and behold, I found this link; http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?search_type=jamecoall&catalogId=10001&freeText=41574&langId=-1&productId=41574&storeId=10001&ddkey=http:StoreCatalogDrillDownView

With this quote;

Bill Garber over at comp.sys.atari.8bit pointed me to:
http://www.jameco.co..._10001_41574_-1
I ordered two of them and they worked just fine.

That blew my mind. Jamesco. $1.69 each.  Think I'm gonna stock up!

So, yeah, try the 4464. According to other forums, it should work fine. Just watch your speed, -10 (100nS) or -12 (120nS) at most should be fine. I found that anything slow might cause hanging at boot up. Please let us know how they work out, so I may update the build document.

[SISKO]

Will do! It may take a while, though. Ill keep you informed. Thanks for the research!

[Govmnt_Lacky]

I have used the TMS4464 chips and they work. Those are the only replacements I have been able to find.

[qwerty8787]

Hi all,

I'm currently trying to make an XP-ALL mod on a XP200.
I found that many components are already there (referring to the guide), like the 74HC574, J113s and others.

I made the adapter for the 27c1001 with breadboard. Eprom programmed succesfully with programmer, using XP-ALL code found on the web.

I'm trying to let it boot fixed on a pedal type (say 200 or 300) just to try it as I'm still waiting for the rotative switch to arrive.
So I just connect A14, A15 and A16 properly to Vss (or disconnected) to choose the right boot option. BUT I have problems: the pedal doesn't starts at all. The screen remains unlit or gets random bars lit.

The other crazy thing is that, when I'm back with the original Eprom, if I just add the other 3 RAM ICs, the unit gets the same strange behaviour. But If I swap the original D41464C-10 chip with one of the news the pedal works. So the new RAMs should be just fine...

Anyone has any advice on my issue? 
Thanks in advance 

[Govmnt_Lacky]

The other crazy thing is that, when I'm back with the original Eprom, if I just add the other 3 RAM ICs, the unit gets the same strange behaviour. But If I swap the original D41464C-10 chip with one of the news the pedal works. So the new RAMs should be just fine...

I have yet to do the mod with the 27C1001 chip but...

According to what you are saying above, you are putting the pedal back to "stock" mode. This would be with the XP200 EPROM in the U9 spot and the RAM chip in the U19 spot. In order to explain better, it helps to understand the following:

XP100 and XP200 ONLY use RAM in U19. The other RAM slots are unused.
XP300 uses RAM in ALL of the slots (U19, U18, U17, and U16)
XP400 uses RAM in U19, U18, and U17. (U16 is NOT used)

If you put the pedal back to original configuration (XP200), then the ONLY RAM chip that "should be" used is U19. I would suggest that you remove ALL of the RAM chips except for U19 and try the pedal. If the pedal is stock, then it should work. If it does not, then you have another issue.

It sounds to me like your NEW RAM chips might be bad. Try what I suggest above with the original RAM chip and get the pedal working. Then, swap the good RAM with a new RAM and see if it still works. Do this with all of the new RAM chips to verify them. If it is good with all of them, then your problem is somewhere in your mod work.

[digi2t]

It sounds to me like your NEW RAM chips might be bad. Try what I suggest above with the original RAM chip and get the pedal working. Then, swap the good RAM with a new RAM and see if it still works. Do this with all of the new RAM chips to verify them. If it is good with all of them, then your problem is somewhere in your mod work.

I concur with G_L on this point. You may have bad RAM. I ran into this problem with RAM that I purchased from eBay seller G&C (Good and Cheap). I bought 10 chips, and they were all crap. I tested them using the same process, inserting them into a working unit.

[qwerty8787]

Thanks for the reply.

Maybe I didn't explained myself in a good way 
If I take the stock eprom (XP200) with only the original RAM, It works.
If I take out the original RAM and I put in a new RAM instead of the original, it works too!

That's why I am assuming that RAMs are just fine.
I get the problem only when I put more than 1 RAM in those sockets. As in the complete mod there's nothing switching out RAMs between modes, I assume that putting 4 RAMs when it is just fixed in XP200 shouldn't be a problem. Or am I wrong?

I can't figure out what's the problem. By now I'm still waiting for the MC34064P, but it shouldn't be necessary for this "fixed mode" pedal...right?

I will also try to program a 27C256 with another code, say XP300, and see if it works. About this, anyone knows if an EPROM with 150ns access time is still good for this application?

Thanks again 

[digi2t]

The MC34064P is critical to the boot up process in the XP-ALL's. It sends an under volt signal to both U10 and U15.

In the original series, the MC34064P was only found in the XP-400, but not in the other three. I think in the 100 the boot up is handled internally from a submask. I'm not quite sure why it isn't used in the 200 or 300, but I don't think that the XP-ALL (+ or otherwise) will boot properly without it.

Having the extra RAM in there shouldn't be a problem, since they are there anyway when running the XP-ALL. Maybe check for bad solder joints where the RAM sockets are soldered to the board?

One thing other that might be happening, is code corruption from your burn. This has happened to me one time. Burned the chip, and it wouldn't boot up. I erased the chip again, burned it again, and it worked fine.

[Govmnt_Lacky]

Having the extra RAM in there shouldn't be a problem, since they are there anyway when running the XP-ALL. Maybe check for bad solder joints where the RAM sockets are soldered to the board?

One thing other that might be happening, is code corruption from your burn. This has happened to me one time. Burned the chip, and it wouldn't boot up. I erased the chip again, burned it again, and it worked fine.

To expound on what digi2t said....

I do not think that your EPROM chip is bad since it works in the stock configuration. I believe you have an issue with another part of your mod work. As suggested above, it may be with the soldering of the additional RAM sockets. You might have to bite the bullet and meter out the data lines between RAMs and the processor and EPROM chips  

EDIT: BTW... did you install the additional tantalum capacitors with the RAM sockets? C61, C64, and C65?