Dual Secondary Tranny PS Issue

[john65b]

Hey all...got myself a ZAPPULSE V2.1 and having a bit of problems with the power supply..

Got a 500VA dual secondary 40V transformer... 40V-0V on one pair and 40V-0V on another. I have two 35A rectifiers and four 10,000uF 63V Caps.

Having a bit of problems here - hooking up the way LC audio advises blows the fuse...

I did have luck pairing the two 40V to each AC input and taking their respective 0V as ground on each amp module....this way I got 56VDC off caps.

Connecting the 0V and 40V on AC input only gets me +/- 28V at each output....

Is there an issue with the way I am planning the Power Supply??

Got a pic below...

[PM650]

The schematic seems correct, though you may have encountered problems from not linking the two grounds (0V wires) together at the supply. The picture you attached may seem a bit confusing, you might want to take a look at Rod Elliot's supply design to clarify things a bit:

Note: The components on the left are not necessary unless you encounter ground loop problems.

[richie00boy]

That first schematic is totally INCORRECT. The two secondaries should join together in the middle to form the ground connection.

The second schematic from ESP is correct and you should try to use that one. The centre-tap can be made by connecting the two 'inner' wires together like so:

0-40 0-40
.....|.|
connect these two

[john65b]

OK, but I seem to remember as soon as I connected the 40V-0V to make teh center tap, I blew a fuse on power supply......

But I will retry again.

[john65b]

Isn't there a PS schematic or design where I do not "make" the centertap by connecting the 40V and 0V?

I seem to think there is a design where the two secondaries feed two completely separate circuits (rectifier and cap bank)...just like two separate trannies...

And why do I get only +/- 28VDC out of the cap bank after connecting the 0V & 40V to the rectifier? I would expect +/- 28VDC output with 20VAC input, not 40VAC...

I have made quite a few PS for Gainclones, UCD180, etc., but this has me stumped...

The Torroid is from another amp...

Don't know if it makes a difference, but the tranny secondaries are listed as 40V 0V (0V) 40V....those parenthesis mean something here??

[BWRX]

You mean like this:


Image taken from here: http://www.zero-distortion.com/techn...powersi_05.htm

[john65b]

I think I tried this - taking the post rectifier + and - from each rectifier to create the zero line - and blew a fuse....

[BWRX]

john, if you blew a fuse wiring up the supply as shown in the schematic in my post then you have a short somewhere or some component is bad or you used the wrong kind of fuse. You said you've made these kind of supplies before so I'm thinking you may have a bad bridge rectifier. Check each of the diodes with your multimeter.

[classd4sure]

With the way you're trying it ... seems like a poor blend of ideas.

It looks like you're trying to achieve some sort of phase cancellation... using a blend of the type of supply BWRX linked to with the one that PM650 linked to. You need to appreciate the differences between the two. One is of the fully isolated variety using the extra bridge rectifier, one per secondary, the other utilizes a typical center tap configuration. You can't have a mix of the two.

What you could do is expand on the ideas and use two more bridge rectifiers to achieve what I think you're after.

It's a little scary that you're using the term "luck" when it comes to a power supply like this. Might I recommend you test your idea on a free simulator like LTspice, before you cost yourself a set of blown up in your face caps or something?

Hope that's some help.

[john65b]

I assure you that I am not trying to do something fancy here, just trying to get -/+56V to my amp module from the dual 40V secondary.

But can anyone explain why I would get 28VDC out of 0VAC and 40VAC connected to the rectifier?

Something still is not right...