thoughts on Digitech Space Station eprom copying?

[digi2t]

Thanks Dino,

Shipping from Nightfire was much more reasonable

J

Glad I could help. 

[mongo]

Well, I finally had time to go back to this, got replacement RAM (I bought RAM from China that COULD  be duds) from a respectable seller in the US, and the result is the same:  clean bypass, distorted output, digital noise, th hint of effects in the faraway background etc.

So, I've oficially reached a dead en here. I assumed it was just bad RAM but now I'm sure it's not only that. I've checked and double checked cap orientation and solder from the RAM sockets and everything seems to be in order.

Could it be that the EPROMS were not burned correctly? how to check it? some guy did it for me and I don't have access to another EPROM burner.

Any hints or help are greatly appreciated.

M+

[Govmnt_Lacky]

Any hints or help are greatly appreciated.

Post some pics of your mod. One quick thing you can do is to turn on the pedal (any mode) and test your voltage regulators to make sure they are outputting the right voltages.

Did you try a factory reset?

[mongo]

Any hints or help are greatly appreciated.

Post some pics of your mod. One quick thing you can do is to turn on the pedal (any mode) and test your voltage regulators to make sure they are outputting the right voltages.

Did you try a factory reset?

Need to scroll through the thread to remember the factory reset, Pics are here, It's a XP400, nothing fancy, I just want an XP300, not interested in the other XP thingies. Volume mod not implemented yet.

[Govmnt_Lacky]

Just from looking at the last pic you posted, I can see that the far right RAM chip (D41464-10 closest to the EEPROM) is NOT seated properly in the leaf socket. Also, that is the ONLY one of the RAM chips that is strictly used by the XP300 chipset.

I would carefully remove that RAM chip, check the chip for improperly bent legs and check the leaf spring IC holder for damage, then carefully reseat the RAM chip into the socket. BE SURE that it is sitting ALL THE WAY down in the socket. (They should ALL look like the far LEFT chip in the picture... that one is seated properly)

After this, do a reset and you will probably get it fixed 

[mongo]

Well, NO DICE. I reseated all the chips, swapped them around and nothing. After that I tried the other XP300 EPROM I have and it produces the same distorted noise with faint hints of effects in the distant background. One thing I noticed just now is the the presets ony go up to 40 and then back to 1. Odd. I swapped to the original EPROM (XP200, I stated incorectly before that it was a XP400) and it works perfectly.

I guess the EPROMS are not ok? What do you think?

Thanks in advance!

Mongo

[Govmnt_Lacky]

Well, NO DICE. I reseated all the chips, swapped them around and nothing. After that I tried the other XP300 EPROM I have and it produces the same distorted noise with faint hints of effects in the distant background. One thing I noticed just now is the the presets ony go up to 40 and then back to 1. Odd. I swapped to the original EPROM (XP200, I stated incorectly before that it was a XP400) and it works perfectly.

I guess the EPROMS are not ok? What do you think?

Thanks in advance!

Mongo

I am confused by this....

You mention that one of the EEPROM presets only went to 40. The XP300 has 40 presets in it.

If the XP200 EEPROM works perfectly when installed, then the problem can only be the RAM chips (specifically U16, U17, and U18), their sockets, or the XP300 EEPROM or it's socket.

BTW... here is how the presets are numbered for each pedal:

XP100 = 01-29
XP200 = 1-61 (skipping all numbers ending in 7, 8, 9, and 0)
XP300 = 1-40
XP400 = 1-50 (skipping all numbers ending in 9)

[digi2t]

The eprom could be verified by doing a read comparison with the .bin file. If there was any corruption, a compare read would reveal it. I always do a compare read before I use a chip, since I've had the occasional corruption issue in the past. Only once or twice mind you, but it's aggravating nonetheless.

One thing that worries me is the ram, specifically the two right most units. I notice that they are stamped with identical serial numbers. This brings back bad memories of the ram I bought from a Chinese supplier. 10 ram chips, all identical numbers. None worked.

Did you try swapping back to the 200 eprom, and then test all the ram with that?

[Govmnt_Lacky]

Did you try swapping back to the 200 eprom, and then test all the ram with that?

I concur 

After re-reading... the fact that you get even "distant" effects (and I assume they are the right effects for the preset numbers) tells me that the EEPROM is probably good.... just probably.

Definitely focus on the RAM chips (U16, 17, and 18) and go from there as Dino mentions above  Swap each one into U19 slot and try with the XP200 EEPROM.

[mongo]

Ok, I'll try the RAM swap and report back. I don't have the means to test the EEPROMS, a guy burn them for me and I don't have a programmer or anything.

I assumed the XP300 had more than 40 presets

Thank you for your answers!

[SISKO]

that is the ONLY one of the RAM chips that is strictly used by the XP300 chipset.

Can you tell me wich RAM chips are used for each xp mode?

[slacker775]

I don't have the doc in front of me but if I remember correctly, the XP-100 only uses the leftmost RAM chip and the other three models use all four RAM banks.

[digi2t]

I don't have the doc in front of me but if I remember correctly, the XP-100 only uses the leftmost RAM chip and the other three models use all four RAM banks.

According to the schematics;

XP-100 and XP200 - U19 (leftmost) only.
XP-300 - U19, U18, U17, and U16.
XP- 400 - U19, U18, and U17 only.

When converting an XP-100 (or 200 for that matter), there's a greater risk of running into ram problems i.e. bad sockets, ram, solder joints, etc. than with a 400.

[SISKO]

Thanks!

[mongo]

Well tried all the RAM I had , same results. It's SO frustrating to be this close to have a working XP300 and not being able to figure out what is wrong with the mod... 

for reference, here's a pic of the RAM I have, on the right, RAM bought from China, on the left, RAM bought in the USA:



and here is a video of my mod in action:

[Govmnt_Lacky]

Is that video with the XP200 chip installed and only U19 populated as discussed in the post above?

[mongo]

No, that's a video of the XP300 chip installed and all the ram slots filled. Same unit with XP200 chip works normally, even with all the ram chips in.

Mongo

[slacker]

I would try it with the XP200 chip and a ram chip in only the U19 socket, swap ram chips in the U19 socket until you find 4 that work, then at least you know you have 4 good ram chips.

[Govmnt_Lacky]

I would try it with the XP200 chip and a ram chip in only the U19 socket, swap ram chips in the U19 socket until you find 4 that work, then at least you know you have 4 good ram chips.

Yep! That's what Dino and I were suggesting earlier.

[slacker775]

I finally got me xp-all completed but I have a slight odd problem.  For background, I burned my own eeprom, the switch seems to be working right, the appropriate LEDs light up and the program's seem to switch properly.  What I am not getting is any effect output.  I did not yet do the output volume mod.  I get dry signal on the 100, 200, and 400 modes but nothing out of 300.  Tuner, bypass, calibration modes all seem to work as expected.  Could it be the eeprom?  Perhaps the wiring around r30?  Any suggestions?