Results 1 to 6 of 6

Thread: Johnson Amplification JM150 LCD display repair...

  1. #1
    Senior Member pecorporation's Avatar
    Join Date
    Jan 2010

    Johnson Amplification JM150 LCD display repair...

    This question may be moot, but I have to at least ask. Is there any replacement parts or repair fixes for the LCD display on a Johnson JM150. Everything works and the amp responds and passes a signal and the back light illuminates the LCD display but the screen is blank, displays no characters.

    Everything I've read online seems to indicated the customer is S.O.L. so I thought I'd check with the experts!

    Thanks in advance,


  2. #2
    Supporting Member Jazz P Bass's Avatar
    Join Date
    Dec 2008
    Wernersville, PA
    Yeah, SOL for sure.
    That display has a character driver chip that is specific to that particular LCD.
    Attached Thumbnails Attached Thumbnails johnson_jm150_featured.jpg  

  3. #3
    g1 is offline
    don't forget the joker g1's Avatar
    Join Date
    Feb 2010
    Canada, somewhere north of Fargo
    Have you tried a re-boot? Otherwise the only generic repairs for displays I can suggest are that some may have elastomer strips that could be cleaned or maybe low power regulators (78L05?) which could go bad. Beyond that, what JazzP said...
    Certified Dotard

  4. #4
    Lifetime Member Enzo's Avatar
    Join Date
    May 2006
    Lansing, Michigan, USA
    A visit to their web site shows 801-566-8800 as the phone, and you can order parts.

    Just for grins, have you tried reinitializing the thing? A bad bit in memory could be sending blanks to the screen.
    Education is what you're left with after you have forgotten what you have learned.

  5. #5
    Senior Member
    Join Date
    Jul 2007
    Needless to say, that you can perform the hard reset:

    1. Press and hold the CONFIG button while powering the amp.
    2. Release CONFIG button after about 5 sec (in fact you
    must see an asterisk appearing in the information line on the screen,
    but in your case LCD shows no information).
    3. Press MOD button.

    If this does not help, see below.

    If encoders affect the sound, the digital core is OK.
    Check control signals on the H15 connector. You must see “low” level on the pin 11 and pulses (at least when you turn encoders) on the pins 10 and 12. If all control signals present and LCD shows no information, you need to order new LCD (its p/n 30-6297-A).
    If at least one of the control signals is wrong, check what’s the matter.

    By the way, do you have the JM-150 schematics? If you need, I can upload it here.

    Good luck

  6. #6
    Junior Member
    Join Date
    Jun 2015
    Tyler, Texas
    Last Time I talked to Digitech, they inform me that they do not support that Amp anymore. I own has the main processor out ( 2101 ) and had NO luck speaking with them...just hate to have to part out such a great amp
    Play Like Your Hair Is On Fire

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Kurzweil PC2X LCD Screen Replacement
    By oc disorder in forum Music Electronics
    Replies: 8
    Last Post: 02-07-2011, 11:18 AM
  2. (possible) LCD monitor repair tip
    By dai h. in forum Fun with computers
    Replies: 3
    Last Post: 05-14-2009, 02:20 PM
  3. Johnson JT50 Mirage Amplifier HELP!!
    By roth135 in forum Maintenance, Troubleshooting & Repair
    Replies: 1
    Last Post: 12-17-2007, 04:24 PM
  4. eric johnson pickup specs?
    By chevalij in forum Pickup Makers
    Replies: 8
    Last Post: 11-05-2007, 04:18 AM
  5. G-Dec display
    By drewl in forum Maintenance, Troubleshooting & Repair
    Replies: 2
    Last Post: 08-15-2007, 03:18 AM


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts