[monsieurguzel]

Hello everyone, i'm trying to build a millet hybrid and have come with a couple obstacles (doesn't everybody?). Well i have pretty much assembled the whole board, including the diamond buffers. The whole setup is connected to a standard wallwart (tread coming soon), however everytime i plug in the power, nothing happens at all. I check all my connections many times and cannot find anything wrong. the only thing i notice is the PF1 fuse gets really hot very fast.

Am i missing anything? I am wondering if i need to sodder TP1 and TP2 since they are left empty....or any other empty sockets since i'm using diamond buffers. Help would be very appreciated. thanks.

more photos at: http://www.flickr.com/photos/aacemyan/?saved=1

 

[seanohue]

you really should test with regular buffers before installing a dDB. But if that fuse is getting hot, then you must have the power supply connections reversed. The center pin of a DC jack is the +. The furthest out (on mine at least) is the gnd. The + pad is the outermost pad in the corner.

Also, what power supply are you using?

 

[dhp]

haha, i bet you forgot to jumper the switch positions

EDIT: oops, missed that part on PF1 getting hot

 

[monsieurguzel]

I didn't forget to jumper the switch. But other than that i'm actually using a 24V .5A Wall Wart from mouser (cost me about $7). I'll double check if i misoriented the power connector...but i had the impression it was correct. Also, is there an orientation for the diamond buffers? and do i need the R6 resistors is i have the DBs?

 

[dhp]

Quote:

Originally Posted by monsieurguzel I didn't forget to jumper the switch. But other than that i'm actually using a 24V .5A Wall Wart from mouser (cost me about $7). I'll double check if i misoriented the power connector...but i had the impression it was correct. Also, is there an orientation for the diamond buffers? and do i need the R6 resistors is i have the DBs?

you forgot to use R6? you can simply jumper it.

 

[seanohue]

Quote:

Originally Posted by monsieurguzel I didn't forget to jumper the switch. But other than that i'm actually using a 24V .5A Wall Wart from mouser (cost me about $7). I'll double check if i misoriented the power connector...but i had the impression it was correct. Also, is there an orientation for the diamond buffers? and do i need the R6 resistors is i have the DBs?

It is 24VDC right

 

[NeilR]

Try powering it up without the buffers in place. There is no correct orientation; they are symmetrical. However, depending on your parts surrounding the buffer, you may be able to misalign the pins, which is difficult to see because the pins are hidden under the board.

The tubes WILL bias without the buffers in place; I have done that many times. Try to get to the point where you can bias the tubes before putting the buffers back in.

Check the orientation of the electrolytics and D1. DO NOT bridge TP1 and TP2; that will short out the buffers. One TP is the output of the buffer; the other is ground. Use one of the ground plane vias for the test point ground; less chance of shorting something out.

If you can post a clear hi res image of the top and bottom of the board, someone may catch something.

 

[monsieurguzel]

Thanks a lot for the replies...i'll try as you suggested. sorry for my ignorance, but i have no clue what you mean by the tubes being biased?

i'll also post a picture up soon to see if anyone can catch anything.

 

[seanohue]

If you look on the board, there are 2 pads next to each other, labeled TP1 and L BIAS TP on the left, and TP2 and R BIAS TP on the right. Stick the black lead of the multimeter in the the TP pad and the red lead into the BIAS TP pad.Those two trimpots on the board correspond to a DC voltage reading on each side of the board. That is the bias of the tubes. By rotating the screw on the trimpots clockwise, you increase the bias and vice versa counter-clockwise.

 

[Samgotit]

Here is an excellent Millet biasing how-to:

http://www6.head-fi.org/forums/showt...ht=millet+bias

 

[Armitage]

monsieurguzel, can you humor seanohue and confirm what kind of wall wart you have, because I'm thinking the same thing. The only 500 mA 24V wallwart from Mouser that Tangent lists on the Tread parts list is AC-AC.

I've bought one and it cost me about $7.00

 

[monsieurguzel]

ohhh...i think you might be right actually. the part number is 553-WAU24-450 . It is a 120 to 24VAC 0.5A. I guess that might be the reason. If i use a tread power supply hooked up to it...will it work, or do i need a new wallwart? Also, have i potentially fried anything in my board? i only would leave it for a couple seconds at a time....

 

[NeilR]

Yes, you need a tread (or some other rectifier/filter) for that AC-AC wart. D1 probably saved your butt. The Millet sort of has a built in half wave rectifier

Good call Sean; I thought about this possibility, but I thought... nahhhh.... he didn't do that

The $7 was the tipoff....

 

[monsieurguzel]

well, i finally built the tread power supply and hooked it up to the power supply...again no luck. The LED of the tread power supply turns on but the millet doesn't power up...i feel that the tread is the problem...all i can tell is the regulator gets extremely hot!

anyways, i posted a couple photos, please tell me if i'm doing anything wrong

 

[Samgotit]

Did you test the TREAD before you hooked it up to the Millet?

The solder joint at V+ on your TREAD looks really strange. In fact, it looks like there is no solder on the pad.