[Erik S.]

Hi!

Just finished my TREAD, plugged it in and it DIDN'T explode

It seems to work fine, but when I messure AC volts between test points 1 and 3, I get 107V

. When messuring DC Volts between 2 and 3, I get 27,8V which is quite accptable since it will be running with the Millett Hybrid.

I use a 30VA, 2x15V dual secondary Toroid with centers tied together, the TREAD kit from Tangent (switched the 680uf cap with a 1000uf 63V since it has a big dent in its side) and a Schurter 6200 IEC (cables plugged into L and N, hope this is right).

So I'm wondering if 107V AC normal between points 1 and 3?
At Tangent's site it says "It should be at least 2V higher than the desired output voltage".

All help appreciated

 

[tangent]

Quote:

when I messure AC volts between test points 1 and 3, I get 107V

Then your meter is either lying to you, or C5's lifetime will be awfully short. With that much overvoltage, I think the fact that it didn't explode in the time it took to take the reading suggests that the former is the case.

Quote:

cables plugged into L and N, hope this is right

Yep.

 

[Erik S.]

Thanks Tangent

I think my meter is lying big-time. When I messure over IN+/- I get 36.6V AC. I borrowed a meter and with this one I get 0V AC over testpoint 1 and 3.

Wondering in which position the leads are going on the meter (red/V-Ohm-mA, black/COM etc.) since I haven't used a meter that much before. Yes, I'm a noob

With black/COM and red/10A, sparks fly when I messured over point 1 and 3 so maybe the fuse in the meter got blown.

The DC voltage still remains the same.

I also get a DC messuring of 48V over point 1 and 3.

Anything else I could have done wrong? The TREAD seems fine, no smoke or explosions.

 

[dsavitsk]

Quote:

Originally Posted by Erik S. I also get a DC messuring of 48V over point 1 and 3. Anything else I could have done wrong? The TREAD seems fine, no smoke or explosions.

My understanding (and you should not rely on me until someone else confirms this) is that the no load voltage of a transformer can be higher than when loaded. Multiply the no load voltage by 1.414 and subtract the voltage drop over the diodes to get the rectified no load voltage. For a 30VAC transformer, 48V doesn't sound too far off to me. (notice here that, assuming that what I said is correct, that you want caps rated at over 50V -- probably 63V -- or else you risk an explosion at some random point.)

Edit: See post 11 in this thread http://www6.head-fi.org/forums/showthread.php?t=109928

Here is a datasheet to see the no load voltage business. http://rocky.digikey.com/WebLib/Amve...ansformers.pdf

-d

 

[Erik S.]

Quote:

Originally Posted by dsavitsk My understanding (and you should not rely on me until someone else confirms this) is that the no load voltage of a transformer can be higher than when loaded. Multiply the no load voltage by 1.414 and subtract the voltage drop over the diodes to get the rectified no load voltage. For a 30VAC transformer, 48V doesn't sound too far off to me. (notice here that, assuming that what I said is correct, that you want caps rated at over 50V -- probably 63V -- or else you risk an explosion at some random point.) Edit: See post 11 in this thread http://www6.head-fi.org/forums/showthread.php?t=109928 Here is a datasheet to see the no load voltage business. http://rocky.digikey.com/WebLib/Amve...ansformers.pdf -d

Seems to be right. Get the same result both with math and messuring.

 

[Megaptera]

Quote:

Originally Posted by Erik S. With black/COM and red/10A, sparks fly when I messured over point 1 and 3 so maybe the fuse in the meter got blown.

10A? Are you sure you're using the voltage setting on your meter? 'A' is amps, which is current.

 

[Erik S.]

Quote:

Originally Posted by Megaptera 10A? Are you sure you're using the voltage setting on your meter? 'A' is amps, which is current.

I know

Just tested it since I got 107VAC at the testpoints to see if I used the wrong setting.

 

[Voodoochile]

Quote:

Originally Posted by Erik S. So I'm wondering if 107V AC normal between points 1 and 3? At Tangent's site it says "It should be at least 2V higher than the desired output voltage".

Well, that is at least 2V higher.

At least two is good, but hopefully not more than 8 or 10V higher. I think something else is amiss also. That cap should be sprayed all over your work area shortly after power up if it has that much power across it.

 

[tangent]

Quote:

Originally Posted by Erik S. Wondering in which position the leads are going on the meter

Black to COM, red to V. The other red is for amperes measurements only. This is in the manual.

Quote:

With black/COM and red/10A, sparks fly

Yes, because you jsut created a dead short from AC input to ground. The fuse in the meter is certainly dead, if it ever had one. And if it didn't have one, the meter may be dead now.

Seriously, read the manual.

 

[Erik S.]

Thanks for all your help

I've already read the manual that came with the meter, if the small piece of paper actually could be called a manual. The fuse is probably dead, but it's easy to swap out. You learn from your mistakes, isn't that what they say

I have adjusted VSET to 30VDC output without any problems and the tread has been running for over 20 minutes straight. The input is 36.4VAC.

With a good meter I get 0.4VAC across test point 1 and 3. Is it another way to messure this instead of using the test points? How important is this messurement when I have acceptable input and output voltages?

I just want to connect the tread to my Millett hybrid that has been collecting dust since easter since no other powersupply has been able to fire it up (Mascot 2083/2183).

 

[BrokenEnglish]

Quote:

Originally Posted by Erik S. I just want to connect the tread to my Millett hybrid that has been collecting dust since easter since no other powersupply has been able to fire it up (Mascot 2083/2183).

your mascots lack some reversed biased protection diodes, that could help them coming up when there's a lot of capacitance in the amp. to work around this issue, try this: first connect the mascot to your millet, then switch the millet on and connect the mascot to mains as last step. it should work then...

 

[Erik S.]

Quote:

Originally Posted by BrokenEnglish your mascots lack some reversed biased protection diodes, that could help them coming up when there's a lot of capacitance in the amp. to work around this issue, try this: first connect the mascot to your millet, then switch the millet on and connect the mascot to mains as last step. it should work then...

Holy ****!!!

It actually works! They're glowing! Why didn't you tell me this earlier

Vielen Dank!!! You just made my day and summer

Now I can use the tread if I decide to make the dynalo

 

[BrokenEnglish]

Quote:

Originally Posted by Erik S. It actually works! They're glowing! Why didn't you tell me this earlier

hehe... bitteschön...

...being a mascot-owner myself i stumbled over these issues many times (with the ppa, later the wna) until david white (the ingenious man behind wna) was able to explain me the ratio behind...

Quote:

Originally Posted by Erik S. Now I can use the tread if I decide to make the dynalo

yeah... but you'll need two TREADs then...