Dead Line 6 DL-4

[kingsteven]

I have a dead DL-4 here which seems to work fine when connected with a 6VDC 1A PSU across the battery terminals but not at all with the Line 6 external 9VAC PSU...

The guy who owns it has been running the DL-4 with a DC PSU (not sure how it works, but it seems to bypass the internal transformer). After a bit of poking around I discovered one of the diodes in the transformer stage has been blown to bits (D16)... I was wondering if anyone could tell me the value/type of this diode or have a schematic of the pedal I could look at?

[pdman]

I too have a power supply problem with a unit I got off of ebay.
My unit will not work with batteries or an external 9 VAC adapter.
I have been trying to find a schematic but no luck.
It looks like I have a couple of damaged diodes but that is all i can tell at this point.
The voltage regulator looks like it is surface mounted and I did get numbers off of that but haven't looked it up yet.
I beleive it was a Maxim chip.
So I can'y really help now but if I can find any info or schematics I'll pass the info on to you.
Good Luck

[kingsteven]

Yep, here's some images... You can see where the blown diode has been removed, I have a few friends with these units, I just have to find one who will let me open theirs up. The two smaller diodes are rectifier diodes (IN4002) and the inductor is a "Tip and Ring Common Mode Filter" (datasheet) It's very hard to understand the flow (without removing a few more components) but for now I'm asuming this is some sort of half rectifying transformer that converts the 9vac input into 4.5vdc... If I find out more information about the blown diode I'll let you know!

[pdman]

I beleive I have the part number for the blown diode.
However it is at home and I am at work right now.
I beleive that the diode is a Zener diode.
Also the surface mount chip on the left is what I think is the voltage regulator.
What seems odd to me is that Line 6 specifies 9 VAC @ 1200ma as the power source requirement.
As I reversed engineered the circuit it seems to me that this current rating is greatly overrated.
Anyways, I'll look for my notes tonight and post the blown diode number as soon as I can.

Also, did you try asking Line 6 for a schematic.
I think I emailed them and was never answered back.

[Mark Black]

I've never received a reply from Line-6 on any email question, and hence have a fairly low opinion of them in terms of customer support.

They adhere strictly to an "authorized service center only" policy, so your only hope will probably be if someone on the forum is authorized and will be kind enough to help out.

One thing I did find out though - after you get the power supply working you may find the unit still doesn't work. If so perform a "hard reset" by holding down buttons A & D simultaneously while powering the unit up. You may have to continue holding them down during the course of the ensuing LED flashing and/or repeat the process to really clear it out.

Good luck!

One other thing - good discussion here: http://www.diystompboxes.com/smfforu...&topic=41142.0

[pdman]

Mark

Thanks for the reply and the link.
Good info on that thread.
It looks like these pedals have a lot of issues with the power supply circuitry.
Anyways will try and troubleshoot later on this weekend.

[kingsteven]

Awesome, I stopped recieving email alerts for this thread so I thought it would be forever as dead as this DL-4

3,6v Zener ( D16 )

thanks guys!

I'll try this out soon and report back...

[pdman]

How's your troubleshooting going.
I have had no time to work on my DL4, though I managed to find a 3.9VDC Zener in my parts bin.
I may use it, hoping that the extra ..3 VDC doesn't blow any other components.

Anyone that has any luck with their broken DL4 please post any successes you have.
Thanks

[kingsteven]

I haven't tried it yet, I have a couple of 3.6v zeners here but they're a lot smaller than the one I removed from the board - I'm placing a big digikey order next week, so I'll get a couple of higher rated zeners then...

If it was my pedal I'd be tempted to build a new DC powersupply stage, but it's on a "if you can fix it you can borrow it" loan from a friend, I'm not going to risk it... There's a guy in later in this thread describing how he did it:

http://www.diystompboxes.com/smfforu...hp?topic=41142