Digitech JamMan Stereo Potentiometer Replacement

Introduction

A heavy object fell on top of one of the knobs of the Digitech JamMan Stereo. The unit continued to function, but the loop level was very low and could not be increased. Upon inspection with a multimeter, it was determined that the potentiometer controlled by the knob was not working. This guide details the process of replacing this component.

The author contacted Digitech support, who provided a replacement potentiometer and knob free of charge. The author notes they are an amateur with limited soldering skills.

Tools Required:

• Multimeter
• Pro Tech Toolkit
• Soldering Workstation

Step 1 - Assess the Damage

Each knob on the unit controls an internal potentiometer. The image shows that the loop level knob was cracked. The replacement parts, a new potentiometer and knob, are shown alongside the unit.

Step 2 - Remove the Knobs

To separate the top and bottom parts of the enclosure, all the knobs must be removed. The knobs are held in place by pressure. They can be pulled off directly or gently pried off using a small screwdriver as a lever.

Step 3 - Unscrew the Bottom Part of the Enclosure

The bottom part of the enclosure is secured by screws. Remove the four screws located at the corners of the bottom plate, as well as the single screw in the center of the bottom plate.

The unit has a label on the bottom indicating: Model No. JML2V-02, Serial No. [Serial Number], FCC, CE, RoHS compliance, and Made in China by Harman Music Group.

Step 4 - Separate the Top and Bottom Parts of the Enclosure

Use a small screwdriver as a lever to carefully separate the top and bottom halves of the enclosure.

Step 5 - Unscrew the Board with the Potentiometers from the Enclosure

Slide the top part of the enclosure to expose the internal components. There are five screws securing the circuit board with the potentiometers that need to be removed.

Step 6 - Disconnect the Cable

A delicate ribbon cable connects components. Handle this cable with care to avoid damage.

To disconnect the cable: First, gently pull the black plastic part of the connector. It will slide a small amount, releasing the cable. Then, pull the cable out of the connector. The black plastic piece remains attached to the board.

Step 7 - Prepare for Desoldering

It is now time to desolder the faulty potentiometer. A soldering clamp can be a useful tool for this task.

When flipping the circuit board, ensure you correctly identify the potentiometer to be desoldered. Double-check and triple-check before proceeding.

Step 8 - Desolder the Potentiometer

The components to be desoldered are small. Using a small piece of desoldering wick held with pliers can make the process easier.

Apply a small amount of flux to the desoldering wick to help it absorb the solder from the joints.

Step 9 - Check the Damaged Part

After removing the potentiometer, it was opened to examine the cause of the damage. As noted in the introduction, a heavy object falling on the knob caused the crack.

Step 10 - Before Reassembling

Before reassembling the device, use a multimeter to verify that all connections are sound and that there are no shorts between the pins of the new potentiometer.

To reassemble the device, follow these instructions in reverse order.