Line 6 DL4 Repairs

[fmashockie]

Hey everyone! I recently did some repairs on a few Line 6 DL4 pedals.  Figured I would share the outcomes on here for anyone's reference.  These guitar pedals are a staple on most pedal boards, but they are notorius for having tons of issues.  I'm sure anyone who uses one religiously has at least gone through more than one of these due to some kind of issue.  So I put some videos of the repairs onto my YouTube channel.  Also, I will attach a full schematic that I found online.  This schematic also includes instructions for putting the DL4 into test mode which can be helpful for troubleshooting.  Be advised this schematic is for the older revision DL4s.  At some point they revised the PCB on the newer models.  The most noticable changes are to the power supply section, the microcontroller, and the cirrus logic audio codec.  But the schematic is still helpful even for these versions.

Repair #1 - Bad audio output stage due to faulty precision op-amp.  Would not even bypass a clean signal. 


Repair #2 - Flashing low battery when battery is not low.  Due to interruption in battery life signal path to U6 ADC TLV0838


Repair #3 - Malfunctioning switches and LED upgrade. 


Hope this is helpful to someone! 

[Calambres]

I have a DL-4 that suddenly failed many moons ago. It was a real favourite of me. I still keep it.

 Thanks a lot! 

[fmashockie]

It's one of my favorites, too! Has always had a place on my board.  Feel free to reach out if you need help fixing yours!

[BarbarianATX]

Piggybacking from the ALL 4 LIGHTS FLASHING (LOW BATTERY) FAULT which I successfully repaired just now, and also replied on the Youtube video for reference:

"Reporting back on the repair unit...

R38 (220k) resistor had totally blown open circuit!  Replacing it (simply used a 1/2-watt through-hole part soldered to the smd pads), then reflowing all the toasted solder joints on R52/R53/D13/D14, and making sure U6 pin6 was soldered nicely restored functionality.  Also did the common fix of removing, cleaning socket, replacing the EEPROM chip.

That was done after previously rebuilding the Power Supply section:
Electrolytic caps (C40 : 1000uF/25V) and (C48, C58, C59 : 220uF/25V)
Diodes (D11, D12 : 1N4002 Schottky)
D16 (1N4729 3.6V 1-watt Zener) new diode raised about 1/2"  off the PCB and tilted away from the 1000uF cap...so that it won't toast the nearby pads like before.

Unit is happy again, as will be the customer.  Cheers!"

- Paul @ GREMLIN Machine Shop FX and BARBARIAN Electronics in Austin, TX.