Author Topic: Line 6 DL4 Power Problem  (Read 4001 times)

jshakesepeare

Line 6 DL4 Power Problem
« on: April 13, 2014, 11:15:53 AM »
Ok, so my DL4 is not powering  up.

I was following Johan's instructions here:
http://www.diystompboxes.com/smfforum/index.php?topic=41142.msg297051#msg297051

And the schematic here:
http://www.aronnelson.com/gallery/main.php/v/MrHuge/Line+6/DL4_ps.jpg.html

I'm getting 3.3 Volts into U20, the voltage doubler (Max660).
However I"m only getting 2.36ish volts out.
I've tried 3 different ICs and they all do the same thing so I don't think that is the issue.
I checked for continuity on everything that should be connected and that is all fine.

Anyone have any idea why this would happen?
« Last Edit: April 13, 2014, 08:00:06 PM by jshakesepeare »

g_u_e_s_t

Re: Line 6 DL4 Power Problem
« Reply #1 on: April 13, 2014, 04:52:17 PM »
power it off, and measure the resistance to ground on the pins of the voltage doubler.  make sure nothing i shorted out.  if new chips dont work as well, it is probably a blown cap on the doubler, or a short further down the line.

jshakesepeare

Re: Line 6 DL4 Power Problem
« Reply #2 on: April 13, 2014, 06:46:06 PM »
Ok, so I did that but the only pins that are grounded are 5 and 6 which is accurate according to the schematic.
Also, I have replaced all the electrolytics just in case.
Not sure if it's relevant, but pins 1/8 are extremely close to ground (about 20 ohms)

Any other possibilities?

g_u_e_s_t

Re: Line 6 DL4 Power Problem
« Reply #3 on: April 14, 2014, 04:43:06 AM »
1 and 8 are the supply rail, which means there is a short somewhere down the line.  perhaps a chip is blown, or if there are tantalum capacitors, they fail by shorting as well.  check to see if anything is getting hot.  what is powered from that line?  you can remove components or cut traces and see when the supply comes back up.

jshakesepeare

Re: Line 6 DL4 Power Problem
« Reply #4 on: April 14, 2014, 12:43:47 PM »
Thanks for your help so far!
Check out the schematic:
http://www.aronnelson.com/gallery/main.php/v/MrHuge/Line+6/DL4_ps.jpg.html

Pins 1 and 8 are connected.
From what I can see the only reason thing that branches from these pins are the 2 capacitors.
I just replaced C48 as 220uF electrolytic.
C65 is surface mount.

Then U21 is a 5V voltage regulator which steps down the 6.6V to 5V.

g_u_e_s_t

Re: Line 6 DL4 Power Problem
« Reply #5 on: April 14, 2014, 02:27:56 PM »
i would assume that the +6.6V goes somewhere other than just the 5V regulator, but maybe not (thats only the PS schematic, so its hard to say where else it goes).  but, if not, then u21 or c65 could be bad, or there is a short on the 5V line.

jshakesepeare

Re: Line 6 DL4 Power Problem
« Reply #6 on: April 14, 2014, 06:15:44 PM »
Ok, so I replaced the 5V regulator and that fixed that problem!
I now have 5 volts coming out of it.

However, the board is still not fully turning on...
I poked around a few places and the ICs seem to be powered but no LEDs or effects are coming out.

I'm gonna keep poking around and see what I can find