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MPX R1 Problem (Read 6291 times)

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#1 MPX R1 Problem
May 24, 2011, 04:57:51 PM
 I have a Lexicon MPX R1 and the Bypass footswitch does not trigger the
tuner function no matter how long I hold it down for (the G2 bypass button
performs this function fine). I also noticed that this same Bypass switch
also makes a lot of double-tapping, even with a firm stomp and turns the
bypass off/on when I am just trying to turn it off. I am wondering if I
might simply just need to change the switch over, and noticed you sell
those and often give advice on these Lexicon units. Could you please let me know if you think a new switch would solve my problem?
 Thank you

Hello, I would suspect the switch, as they are now starting to fail in the R1's or another thing that seems to be happening with them is the spring within the push button actuators are starting to get compressed and when taping the button the spring does not have enough length or tension to activate the tap switch.

On the R1 you do not need to take the PC board out to test the tap switches, with ohm meter. Remove bottom cover and all leads are right in front of you. You can tell which leads you need to connect the ohm meter to, as you can see the tracers on the pc board that lead to the pins used on the switch. A good healthy switch in circuit should read between 39 ohm and 41 ohm. I think the bypass switch has only one trace going to it so only one side of the tap switch is used.

If the switch passes your ohm test then you would need to remove the PC board to get at the switch actuators to check out the spring. You can remove them from the body of the actuator by removing the nut at the bottom of the actuator body, just note how it comes out as they are tapered springs and need to go back in the same way. Try stretching the spring out a bit to give it a bit more length.

Note: While you have the PC board out would be a good time to replace the battery as they are at the end of their life span and will eventually start leaking acid, this can do some nasty harm to the PC board.

Thanks for following up Keith!  Unfortunately, i stretched the spring on the Bypass switch and it still doesn’t trigger the tuner if held.  In fact it might be a bit worse than before.  What are my other options?

Noe did you check the switch out with an ohm meter first? should be around 40 ohms. I guess maybe I should have said stretch the spring just a small bit,   Another thing I was thinking you may try, is to re-flow the solder on the switch pins. The way to do this is put the solder iron to a pin and the second you see the solder melt pull the iron away, do this to all 4 pins. Also try holding down the #1 switch while power up and see if you get any E codes. When you press switch #1, you should see 04 on the display, this means you are in diag mode let go of #1 switch. The test you are most interest in is to press switch #4, this tests the switch relay, if it passes test you will see a P on the display, if the test fails you will see an E4.

Thanks Keith, will try asap! I Don't have an ohmeter handy, but it sounds like this test should troubleshoot it without one anyway.
Thanks again, will def keep you updated. I have been so disappointed with the G2 and R1 units (only had them a few weeks) as it has been almost nothing but trouble. Still, I see huge potential in it, if I can get it working right it would be downright the best effects unit ever, just so many options and the sounds are great. A bit more processing power wouldn't go astray so more fx could be run simultaneously, but then again I like to set the eq as a solo boost (and the eq appears to be a real processing sucker). Anyway, I will keep trying in hope to solve all these little glitches. Thanks one more time! Will keep in touch with my progress for sure, you are just so helpful.  I would have definitely sold it by now if I hadn't spoken to you!

« Last Edit: May 25, 2011, 12:14:46 PM by Keith »
Mapex Pro M Maple standard, Pearl 800 series cymbal stands, Vex hi hat stand, Pearl P201P double bass pedals, Tama mid level throne, All Zildjian A cymbals, 21" Rock Ride, 18" med thin crash, 16" med thin crash, 10" splash, 14" new beat hi hats.