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1
MPX G2 / Re: Can't Exit Edit Mode
« Last post by bsellon on January 17, 2017, 01:15:37 AM »
I would also run the button test in the diagnostics. Press and hold the Edit button while powering up I believe.

There is also a possibility that the some bad value has gotten into memory somewhere either from a bug or a component failure and is somehow managing to prevent the system from going into the Program select mode.  Because of the Program Chains, Midi Program Maps, etc. the Program mode is not actually that simple in terms of code and could possibly be derailed by some corrupted memory but I was thinking that you might be able to get it to run a full factory initialization by lifting one of the pins on the battery and leaving it overnight. On power up, the G2 is expecting to see a few specific pieces of data at specific locations in the battery backed up RAM to indicate that the initialization has already been done. If the battery is disconnected for a while the data in the RAM gets randomized so the G2 should perform a clean startup. It's also worth looking in the diagnostics in case we put something in there to reinit memory (it's been a while).
2
MPX G2 / Re: Can't Exit Edit Mode
« Last post by NotASpeckOfCereal on January 16, 2017, 11:51:20 PM »
Another thing occurred to me as I was re-reading the full post: another possibility is that padding on the plunger for the edit button came off and is stuck on the board causing the button to be permanently pressed.

Thanks Bob.

I got all of that taken apart, made sure none of the soft buttons were permanently pressed or their conductive parts mucked up. Nothing there.

So I ended up shorting the wire grids you speak of. I found that I could actuate every button except for the PROGRAM button.

NOTE: just to be sure it's clear, I started this thread saying that the EDIT button was stuck, but that's not the case. It turns out that I could get into the SYSTEM, STORE, EDIT, and all other buttons except PROGRAM. So the statement "can't get out of EDIT mode" is still mostly true, but only because the PROGRAM button is the faulty one (meaning I can't change patches/programs, so forever in Edit mode).

Also, the KNOB is wonky (this unit took a fall once), so I could use the entire assembly, which is listed as Item 14 on page 8-49 of the service manual. On page 8-51, it's listed as Part #750-11565.

Digikey doesn't seem to have any Lexicon parts (they aren't listed on http://www.digikey.com/en/supplier-centers). The part number doesn't turn up anything.

Should I contact Lexicon through their web site? They seem to want to point me to service centers, which means parts mark-up and labor, perhaps shipping.

I'm not currently employed and this is a plug-in part, so I can do this work myself if the part is affordable enough.

Thanks, Chris
3
MPX G2 / Re: Can't Exit Edit Mode
« Last post by bsellon on January 16, 2017, 10:54:48 PM »
Digikey is your best bet for parts though some might only be available through Lexicon.

Another thing occurred to me as I was re-reading the full post: another possibility is that padding on the plunger for the edit button came off and is stuck on the board causing the button to be permanently pressed.

If you look at page 8-43 in the service manual you'll see the schematic page for the front panel. The buttons are set up on a 4 x 5 wire grid where each button shares the wire with others. On the schematic you'll see that the PROGRAM button is on the same wire as the GAIN, EFFECT 1 and  EFFECT 2 buttons vertically (when the page it rotated) and the EDIT, SYSTEM and STORE buttons horizontally. If all of the other buttons are working, then the problem is not a chip.  You should be able to short pin 8 of J2 to the cathode (the side with the line) of the diode D32. If that causes you to get into the Program mode, the problem is the connector or etch leading to and including the switch contacts and that you can probably finagle a replacement momentary button.   

4
MPX G2 / Re: Can't Exit Edit Mode
« Last post by NotASpeckOfCereal on January 16, 2017, 06:35:23 PM »
Can someone point out a good path to follow to order the part?

Also, if I can find this part, I might be interested in picking up v1.1 of the system. I'm still on v1.0.

Any contact info is appreciated.
Thanks,
Chris
5
MPX G2 / Re: Can't Exit Edit Mode
« Last post by NotASpeckOfCereal on January 16, 2017, 06:28:49 PM »
Hi all,

I think I've identified the part I need to replace to get this Lexicon MXP G2 working again.

I have the service manual that I picked up on this site and have ID'd the item and part number.

Can someone point out a good path to follow to order the part?

Thanks for any help,
Chris
6
MPX G2 / Re: Can't Exit Edit Mode
« Last post by NotASpeckOfCereal on January 07, 2017, 05:32:02 PM »
Hi Bob, delayed reply.

Thanks for the post. I saved it for when I had time, which was last night.

I took it apart, took off the rubber front with the conductive contacts, and was able to switch buttons back and forth using a screw driver (with a rubber handle to be sure) by touching it across the circuit mesh (what the conductive backing part of each button would normally do).

I conclude that all buttons work including the Edit button, but except the Program button (so 7 of the 8 buttons work, some of them such as the left/right arrows only when in the proper sub-menu of course). I can activate all of the other LEDs with the screwdriver except the program button. I can get into the System menu, find the Init, and reset the entire device back to factory settings, but when done, it goes back to the Edit button, or at least, the Edit button is the only way to exit the System menu.

I suspect that the Program button would exit system, and that it is also the method to leave the Edit menu, but I just can't do it.

I even tried removing the main ROM chip (the v1.0 I think would be replaced were I to get the v1.1 chip) and fire it up, then replacing the ROM chip hoping that this would clear the button state, but it didn't.

So I'm at a loss now at how to fix this device. It's a shame to throw it away. Perhaps replacing that one board behind the buttons?

Chris


7
MPX G2 / Midi phantom power breakout box for MPX G2 & R1
« Last post by hapsong on January 03, 2017, 05:36:58 PM »
I have a custom midi phantom power breakout box and AC supply that works great with the MPX G2 & R1. It allows you to power the R1 and additional stomp boxes all through the 7-pin midi cable coming from the G2. It is for sale on ebay - you can check the details at http://www.ebay.com/itm/modified-Pedal-Power-midi-phantom-power-breakout-box-AC-supply-Lexicon-MPX-/222367981949?hash=item33c62a217d:g:s6QAAOSw-4BXcYmU
8
MPX G2 / Re: MPX G2 and buffers
« Last post by bsellon on November 15, 2016, 01:46:10 AM »
What are you adding the buffers for? Signal level or tone? If the buffer is going to be affecting the tone, you might want to keep it in front of any reverb and delays though a distorted echo on a clean guitar can be interesting. 
9
MPX G2 / Re: Creating Tap Tempo for MPX G2 delay on MPX R1
« Last post by efoster on November 09, 2016, 10:09:20 PM »
Bob,

That was the ticket!  Great memory.  Works as advertised.

Thanks, again, for your generosity with your time.

e
10
MPX G2 / MPX G2 and buffers
« Last post by efoster on November 08, 2016, 12:53:38 PM »
I'm considering adding at least one outboard buffer pedal to my setup which is currently:

guitar --> aby splitter ==> output 1 to L side of stereo volume pedal --> Dry Amp
                                         output 2 to R side of stereo volume pedal --> Tease wah pedal --> ProCo rat --> G2 input --> Wet Amp input
                                                                                                                  Wet Amp FX Loop --> Eventide H9 --> Ehx Cathedral --> G2
                                                                                                                        --> Wet Amp FX Loop Return

I have read in some of the G2 manuals about buffers already included in the circuits and am curious if they are already doing the job I'm wanting done on the G2 side of the house.  If not, this would leave me (I'm thinking) with options of a buffer post G2 into the FX Loop return or a buffer pre G2 guitar input.  I'm trying to figure out how to get it into a support position in the signal chain that would allow me to keep it out of the way of the Fuzz circuits or other front end effects with which it may not play well.  It takes a lot of cable to get this done, and my tone is a tad dark, so I'd like to address it and leave my self the option of going dark when I want to, not because I've sucked all the treble out of my tone with my chain.

Thoughts?

Thanks,

Ed
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