Digitech XP All debugging

[Rockmusikeren]

I have modded this XP-100 into a xP-all some years ago, used the m27c1001 eprom, it seems to work perfectly until I switch to the XP-100 mode and back to another XP-xxx, then it goes silent, numbers and switching still works, but no sound until I remove the power and wait for 5 minutes, plug it back in and it works again until I switch back to the XP-100 mode - It works in the XP-100 mode, it is when I go from XP-100 to another XP-xxx the problem starts.

I hope someone can help me!

[antonis]

If we only be able to catch your mods.. 

Brute approximation for time_only_delay_working effects is some big power supply electro cap..

[digi2t]

Just so I understand correctly;

You modded the XP-100 into an XP-ALL "some years ago". Has the problem always existed, or it's appeared of late?

First, I would check your switch. It should be a BBM (break before make) type switch. This is what the MC34064 needs to trigger the power reset sequence. The contacts in the switch might be defective, possibly loose in the first position, not breaking cleanly going from XP-100 to something other mode. This might be a cause.

The MC34064 undervoltage sensing IC (U13) is responsible for the power reset switching. C28 (1uF/50v) capacitor is the timing element. I wouldn't point the finger here, since it's only happening in the "XP-100 to something else" sequence, but something to think about.

Have you tried doing a factory reset?

[Rockmusikeren]

Hi digi2t

Thanks for replying to my post!

Yes the problem has always been there, I tried to burn a new Eprom, but it's still the same, so I guess it's not the problem.

Maybe it could be the switch, I will have to check it again. I tried to lift A14 as I read in this forum it was not needed but
it didn't change anything.

I have done a factory reset, but the problem persist. 

[Rockmusikeren]

Btw! In the long thread about converting this, there was a guy (mitchschaft) who had the same problem,  at page 30.
But I don't know If he ever solved it, he also used the adaptor board and had the same issues. 

[digi2t]

Btw! In the long thread about converting this, there was a guy (mitchschaft) who had the same problem,  at page 30.
But I don't know If he ever solved it, he also used the adaptor board and had the same issues. 

Reading further into the thread, it would seem like MuThing also encountered the same problem. Apparently, it perhaps stems from a problem with the relay switching. I myself have never encountered this problem, but I'll take a closer look when I have some time.

I would PM MuThing, and ask for details.

While we're on the subject of the relay, what manufacturer/model relay did you use for your build?

[Rockmusikeren]

Yeah I read something about the relay switching somewhere in the thread, I hear the clicking from the relay forth and back from XP100 mode.

The relay I used is the Omron G5V-1

Would be great if MuThing solved the problem

I traced all the wires from the alp rotary switch and it looks to be as it should be, measured the terminals too and they too seemed okay.

[Govmnt_Lacky]

Rockmusikeren,

Did you use an adapter PCB for the 27C1001 EEPROM? I am assuming you did since you referenced the switching relay.

If so, can you post up pics of your build? I think I may know your problem but, I need to see how you built it. Specifically, the wiring and connections between your adapter PCB and the rotary.

[Rockmusikeren]

Hi Govmnt_Lacky

Yes I used the adaptor board made by marmaliser.

It's a bit messy as it is now, hope you can see what you need in the pictures.

[Govmnt_Lacky]

Ok... couple of initial questions:

- From what I can see, this was an older XP 100 pedal. The type that had the XP 100 program on an EEPROM chip and NOt in the processor masking, correct?

- Whats the deal with the wire attached to the mounting screw? What is that there for? EDIT: Nevermind. I see you are using that to GND the LEDs

- What is the exact Part number of the RAM chips you are using? I would definitely look at those to make sure they are seated VERY tightly and that they are ALL the exact same part number. Especially the number after the dash. They should ALL be -10s or -80s

[Rockmusikeren]

It's not the one with the program in the EEprom, there where one ram chips in the build before i Modded it.

All the ram's are -10 and I tried to change them with others, it didn't make any difference.

You are right it's for grounding the led's

[Govmnt_Lacky]

It's not the one with the program in the EEprom, there where one ram chips in the build before i Modded it.

I can tell from your pictures that your XP 100 was the older type (i.e. already had the SMD chip installed in U8 and had an EEPROM installed in U9)

Which XP ALL program do you have on the EEPROM? If it is the XP ALL In then I believe (Dino or Prehistoricman can correct me) you do not need the relay setup anymore as the coding was changed to allow stereo output with the XP 100 mode.

To capture more data for troubleshooting, please do the following:

Remove power from the pedal. Put rotary switch in the XP200 setting. Power on the pedal. Check for audio output on BOTH outputs.
Repeat this process for each of the other XPs. Remember to remove power and switch before re-applying power. Be sure to check BOTH outputs.

Reply with results.

[Rockmusikeren]

Okay, I think I misunderstood you, it is the one with chip in U8 and so on.

I tried both the XP-all and The XP-all In, didn't change anything regards to my problem.

I checked the output as you said and there is sound in both outputs in all XP modes.

[Rockmusikeren]

I gave it a try and removed the relay and the problem was gone, I can change back and forth from XP100 mode and it works as it should, only problem now is I have only sound in one side in XP100 mode. So there must be a problem around the relay

[Govmnt_Lacky]

I gave it a try and removed the relay and the problem was gone, I can change back and forth from XP100 mode and it works as it should, only problem now is I have only sound in one side in XP100 mode. So there must be a problem around the relay

Based on your test results above, I was going to say it is either

- Bad Relay
- Bad soldering with the relay or associated wiring
- Short at R30 (where the relay wiring connects to the XP PCB.

Good luck. Almost there 

[digi2t]

OK. I'm using the same relay, but haven't had a problem TO DATE...

Now, if the relay is the problem, I'm wondering if maybe the coil needs a flyback diode. Maybe it's coil bounce that's causing the problem? At this point, the relay might be damaged, so I would replace it. I would add a 1N4148 diode across the relay coil, diode cathode to the positive side.

Since there has been more than one occurrence, there may be a revision in the wings for the adapter board. Since there are relay units out there, it would be important to have a solution and workaround ready.

The latest XP-ALLin code which reinstates audio to the stereo side brings a wet signal. The original XP-100 output wet on the mono side, and dry on the stereo side. The relay simply brings back the dry stereo side, post mod. This is really personal choice as to which you prefer. We didn't know that the code would be advanced to the point of bringing wet output to the stereo side in 100 mode, so the relay is really an element of evolution.

Personally, I would ditch the relay, and go with the latest code. Wet/wet in 100 mode is fine. Besides, losing the relay takes some of the load off the main regulator. I haven't tried the latest code myself, but if it works as advertised, it's a good update.

[Rockmusikeren]

Tried another relay, still the same result, so maybe there are a fault on the adaptor board..hmm!

I think i'll go without the relay, my head can't take anymore debugging today

Thanks for your help Digi2t and Govmnt_Lacky!!!

[Govmnt_Lacky]

Tried another relay, still the same result, so maybe there are a fault on the adaptor board..hmm!

I think i'll go without the relay, my head can't take anymore debugging today

Thanks for your help Digi2t and Govmnt_Lacky!!!

If removing the relay lets the pedal work completely correct, then the problem must be either with the adapter board OR the wiring between the adapter board and the XP PCB/Rotary (the relay wiring)

[Rockmusikeren]

You are right Govmnt_Lacky and I have checked and double checked the wiring and soldering. Next move is to try out with a prefboard and if that works
there must be a flaw in the adaptor board.

[digi2t]

Is that an OSH Park board?