Line 6 DL4 Power Supply Mod questions

[soundaudiorepair]

Hi,

I picked up a broken Line 6 DL4 that wouldn't turn on. The problem turned out to be the power input jack switched connection was broken, so nothing was grounding to the power supply. Pretty simple.

But I spent a lot of time looking at this power supply and I think its kinda...dumb?

It calls for a 9vAC 1200ma power supply. But that is just rectified through a zener diode down to 6v. And the amp draw on that 6V is only 200ma (I checked). Plus the 6v goes into a MAX887 Voltage regulator which is can handle up to 11v input according to the datasheet.

Is there any reason I shouldn't just bypass the rectifier circuit and just run this off a normal 9vDC supply with appropriate mA rating?

I've attached the schematic of the power supply.

[vigilante397]

First of all, welcome

Second of all, that is definitely an interesting design choice to say the least, and definitely not a choice I would have made. They're taking a 9VAC input, rectifying it to get 6VDC or so, regulating that to 3.3VDC, then doubling that to 6.6VDC, then regulating that down to 5VDC. What the actual hell?

My only question, is there anywhere else in the circuit that the V+ goes? And if so, is there any particular reason it has to be 6V? My personal feeling would be that a 9VDC input would be perfectly fine.

[soundaudiorepair]

First of all, welcome

Second of all, that is definitely an interesting design choice to say the least, and definitely not a choice I would have made. They're taking a 9VAC input, rectifying it to get 6VDC or so, regulating that to 3.3VDC, then doubling that to 6.6VDC, then regulating that down to 5VDC. What the actual hell?

exactly.

My only question, is there anywhere else in the circuit that the V+ goes? And if so, is there any particular reason it has to be 6V? My personal feeling would be that a 9VDC input would be perfectly fine.

As far as I can tell, V+ only goes through a switched contact on the input switch and then back to the SHDN pin on the 887. So just used to turn the pedal on. Full schematics are here though: http://www.freestompboxes.org/viewtopic.php?t=23282&p=256501#p229473

[PRR]

...They're taking a 9VAC input...

OR a four-cell battery.

As I already remarked on*another* forum, it smells like a bodge, maybe to use-up a crate of wall-warts.

[DIY Bass]

I have an M13 which also uses the 9V AC supply.  I suspect that it is just their standard supply with power supply circuitry adjust to suit the use.