Silver Bullet Meter LED Issues

If you are experiencing issues where a portion of the meter does not illuminate you may have a faulty LED.  The 20-segment meter is comprised of three series of six and seven LED strings (6+7+7=20).  When one LED is faulty, then the entire string of 6 or 7 LEDs will stop illuminating.  Thankfully this is an easy problem to address.  To determine which LED is bad you will want to feed in a low level 1 kHz sine wave signal and slowly turn up the Gain and Output of a single Mojo Amp so that each LED illuminates one at a time.  When the signal level is high enough to trigger the faulty LED the entire string will go out.  The bad LED is the one immediately to the right of the last one that successfully illuminated.  For example, you slowly turn up the gain and are able to get all the LEDs upto -4 to illuminate, but once you reach -2 then all the LEDs from -10 to +2 go out.  The -4 LED was the last good one to illuminate.  This means the -2 LED is bad and must be replaced.

The following 3mm white LED can be used as a replacement: VAOL-3GWY4

To remove the meter board from the unit and complete the repair, perform the following steps:

  1. Power off the unit and unplug the PSU.
  2. Remove the top cover of the unit via the 7 countersink screws.
  3. Disconnect the ribbon cable from the connector on the back of the Meter PCB by gently wiggling and pulling it from the connector.
  4. Remove the three #4-40 hex nuts that fasten the Meter PCB to the front panel.
  5. Carefully remove the Meter PCB from the threaded studs on the back of the front panel.  Only touch the PCB on its edges and ensure you are grounded by touching the chassis.  This board is sensitive to electrostatic discharge.
  6. Set aside the two vinyl spacers that are fitted over the "ON" LEDs.  They serve as light shields.  Sometimes they stick inside the slots for the Meter windows.
  7. Remove and replace the faulty LED.  If you are not skilled with desoldering and soldering components, then we only recommend a capable technician do this repair.  Be mindful of of the orientation when replacing it.  The square pads on the PCB denote the cathode.  All LEDs are orientated in same direction so you can match the orientation of the other LEDs.
  8. To reassemble, perform these steps in reverse.

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