Strange voltage curves

[Edwin Dorre]

Hello,

I have a working Aleph 4, however when I look with a scoop on the traces of the + and - voltages of left and right channel I get very strange views... Only the first trace looks like I would expect. both channels are wired the same. They are all very different. Timebase and amplify are all the same for all pictures!

I have 0.22uf 250V around the rectifier bridge and across the + 0 - side of the elco's. You can see this on a picture below.

channel 1 +


channel 1 -


channel 2 +


channel 2 -


Help what can it be!

Edwin

[Edwin Dorre]

And a small picture of my Aleph 4!

[tiroth]

none of your pix work

[Edwin Dorre]

Originally posted by tiroth
none of your pix work

strange, I just rechecked on a other PC and the work... perhaps the internet is slow to by providers server. It is located in the Netherlands.

Edwin

[blank527]

Pics works fine by me!
Great work!
Strange voltage readings, have'nt got a clue.
Are these readings taken whilst with a source, or with no source.
Maybe it changes when you put your source off.
Remco

[fcel]

Are those Phillip 26000uF/75V capacitors with the 3 connectors? I hope they are not the cause of the "problem" because I just bought a bunch of them.
By the way, if they are 26,000uF each, why do you need some many per channel? You just want to do way overkill since it's DIY?

[Edwin Dorre]

Originally posted by fcel
Are those Phillip 26000uF/75V capacitors with the 3 connectors? I hope they are not the cause of the "problem" because I just bought a bunch of them.
By the way, if they are 26,000uF each, why do you need some many per channel? You just want to do way overkill since it's DIY?

For the record; these are pictures of the power supply + and - rails... not of the output or input of the amplifier.

The channel 1 has the least hum.

They are 63V 22000uf BC components (philps) with 2 times M5 screw on connectors.

Yes, DIY overkill! To lower the ripple of the powersupply, however something does not work!

Edwin

[fcel]

1. Does the transformer has shielding?
2. Did you try installing the transformers side by side instead of on top of each other?

[Edwin Dorre]

Originally posted by fcel
1. Does the transformer has shielding?
2. Did you try installing the transformers side by side instead of on top of each other?

The transformers do not have shielding. They are 1000VA 40-0-40 transformers.

I mounted them on top of each because of easy fixing. I did not try to move them around, as they are bolted on to the wood, and soldered with thick wires (do not bend easy). Can this be a part of the problem? I looked once in a Plinius amp and they do the same trick.

Edwin

[HDTVman]

Edwin a couple of quick questions.

1. What do you have as a load for the amp while testing?

2. Do you have the bias set for both channels?

3. Is there any DC ofset at the output?

Just looking at the scope traces it looks like channel 2 has a higher bias current setting than channel 1. It also looks like there may be a - offset in both channels (more current from the - supply that the + supply).

The only other thing I can think of that would cause a wave form like this is that some of the power supply caps may have a bad connection of are defective.

Hope this helps.
BZ