zen v1 build problems????

[fligti91]

right they are flipped on opposite sides of the board, right?

 

[Magura]

here is my heat sink, how do you think ill be with this?

That is not much for two channels. You are going to dissipate close to 300W of heat, if you stick to the 0R22, as in 3A bias.


I used something like 6 or 8 times that, and still I had it running at the wrong side of good.


Magura

 

[Magura]

right they are flipped on opposite sides of the board, right?

Yes, so the trick is to figure which is which, hence the trick about looking for where R1 is connected.


Magura

 

[fligti91]

holy crap! ill have to order some higher value resistors then

 

[Magura]

holy crap! ill have to order some higher value resistors then

Don't you have some extras of the 0R22 ?


Magura

 

[Iain McNeill]

nicely sleuthed Magura

 

[fligti91]

ok so i powered it up with the pins soldered correctly. the 6 amp fuse blew right away. so i disabled one channel and the fuse didnt blow. and i checked for voltage at the drains and found 22v(half of the input). after letting it sit for a minute like that i came back to it and found the drains to be at the same as the input voltage 43v. this is driving me nuts! i obviously screwed up the mosfets wiring originally but now im thinking i blew them because of it???
you all have been a great help and have already shown me where i was wrong, please dont give up on me, lol.

 

[Magura]

ok so i powered it up with the pins soldered correctly. the 6 amp fuse blew right away. so i disabled one channel and the fuse didnt blow. and i checked for voltage at the drains and found 22v(half of the input). after letting it sit for a minute like that i came back to it and found the drains to be at the same as the input voltage 43v. this is driving me nuts! i obviously screwed up the mosfets wiring originally but now im thinking i blew them because of it???
you all have been a great help and have already shown me where i was wrong, please dont give up on me, lol.

I didn't give up on you, but we have a few hours time difference.


Does the voltage at the drains change at all when turning the potentiometer?

Usually when running mosfets this hard, you have little doubt if they're goners, but it's been seen that they die silently.

The easy solution (if you have the parts) is to replace the mosfets. The a bit more complicated solution, is to remove the mosfets from the circuit and test them.

Here is a guide: http://www.passdiy.com/pdf/mos.pdf


Magura

 

[fligti91]

would you all have a recommended part number for an inductor to use on my 43v to bring it back down to the 34 v the circuit was designed for? im going to have to order some new mosfets and power resistors

 

[Magura]

You can't reduce the voltage that much with an inductor, but the voltage is not really a problem. I usually play with stuff like this, pushed about as hard as you do here.

Just order some 0R33 and 0R22, and a bunch of mosfets, since you're going to build something more fun later anyways
A few MPSA92 may also come in handy.

Magura

 

[fligti91]

ill keep that in mind when i place my order. your right! as much problems as im having im learning so much and im having so much fun!

 

[Magura]

Looking at the photo you sent me, the MPSA92's are turning the wrong way. The silk screen is wrong, they must be soldered in opposite the silk screen. See the image I attached earlier in this thread)


Magura

 

[fligti91]

so do you think the mpsa92's are bad now to?

 

[Magura]

so do you think the mpsa92's are bad now to?

Hard to tell from here, but they're real cheap


Magura

 

[fligti91]

i hear you, lol. ill replace them just in case

 

[Magura]

We might as well keep this public, for others to use.

Which voltage are your PSU caps (C1 and C2) ?

I'm thinking that your supply voltage is 43V, so the caps must be rated at least 50V.

Magura

 

[fligti91]

thats y i asked about lowering my input voltage, my caps are rated at 35v. the 2 on the rectifiers are rated at 50v as they are before the chokes and i was thinking th chokes would drop the voltage on the other side of them

 

[Magura]

Ok, the quick solution is to remove the caps on the C1 and C2 from the PCB.

Then connect the secondaries in parallel after the bridges. Then use one of the 50V caps, place the inductors in parallel, then the second 50V cap. Now connect both channels to the same supply.

Magura

 

[fligti91]

based on the heat sink im using would it be better if i just switch to using a 25v rated secondary transformer?

 

[Magura]

Yes, but I guess it's cheaper to just get another heatsink to add?

The benefits of running higher voltage are not all that small.



Magura