Question: Why can't I disengage Lead 2? Help please!

The Boogie Board

Help Support The Boogie Board:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

rlord1974

Member
Joined
Jan 9, 2010
Messages
17
Reaction score
0
Hi All:

When I turn my Quad Preamp on, the Lead 2 LED is already lit. According to the users manual, this should not occur as, during power up, the Quad should revert to a "no mode" status until a particular mode is actually selected by the user by way of the footswitch or use of the external switching jacks.

In playing through it I have determined that Lead 2 is always engaged/activated - that is, even if I engage Rhythm 1, 2 or Lead 1, the Lead 2 LED remains lit and the Channel 2 controls still impact the tone.

I have tried disengaging/deactivating Lead 2 using the Lead 2 external switch jack on the rear of the unit, but it remains engaged with the LED on.

I have tried disengaging/deactivating Lead 2 using midi program change commands (I have the rare midi Quad), but it remains engaged with the LED on.

Has anybody ever had the same or similar problem (i.e., one of the channels being permanently activated) and, if so, can you offer any advice as to how to resolve the issue? Perhaps I can fix it myself, or maybe I need to take it to a tech?

Thanks!
 
Could be an bad optocoupler (they are used for switching). Finding which one is another story !
 
I have repaired this problem a couple of times. Usually it is the 7406N chip (this drives the front panel LEDs and a number of optocouplers depending on the function). It is located towards the rear of the PCB and is pluggable.

Do not attempt to replace this yourself unless you are competent to do so as there are high voltages inside even after the unit is depowered. Inserting a replacement IC the wrong way round can cause severe damage to the preamp.

Sometimes the optocoupler can cause this chip to fail but it's worth replacing the chip first.

Have fun.
 
Oh, I had forgotten I ever posted this here! This problem was resolved a day after the original posting. All I needed to do was flick a switch on the back of my midi Quad to select the Abacus instead of the FU-2. Easy fix. Sorry for the alarm bells! :lol:
 
My Quad preamp will turn all the channels on by itself. It will do it no matter what I use to change channels. I unplugged all the cables and it still does it. Here's a video -



https://www.youtube.com/watch?v=PiMC7PW_fbg
 
Back
Top