[fc911c]

Hi

I am just finishing up the build and wanted to know why C37 and C38 use a 50V cap? I guess I ordered wrong and don't have any, the highest I have are 35V. I am assuming that there is a reason why it's 50V. Can someone explain it to me and why so high when the supply volts is 15v? Also could I use the 35v in the meantime or I have some big 2200 50v. The C37,38 are 220uf btw.

I have 3 builds going at the moment and and can't complete any because of a missing part on each.I wanted to hear something coming out from any of these LOL.

Thanks for the help
Frank

 

[cotdt]

35V is fine, it doesn't even reach near that voltage.

 

[amb]

The reason why a 50V cap is listed in the BOM is because for the recommended cap types, the lead spacing for the 50V version gives a perfect fit on the board.

 

[fc911c]

Thanks

one more question if you know and I think I am good to go. I am putting the transformer in another case, do I need to run a ground wire from the wall to the amp along with the 4 transformer wires?

Thanks
Frank





Quote:

Originally Posted by cotdt /img/forum/go_quote.gif 35V is fine, it doesn't even reach near that voltage.

 

[fc911c]

ok I got it. also my 35v caps have this spacing

Thanks

Frank


Quote:

Originally Posted by amb /img/forum/go_quote.gif The reason why a 50V cap is listed in the BOM is because for the recommended cap types, the lead spacing for the 50V version gives a perfect fit on the board.

 

[amb]

Quote:

Originally Posted by fc911c /img/forum/go_quote.gif one more question if you know and I think I am good to go. I am putting the transformer in another case, do I need to run a ground wire from the wall to the amp along with the 4 transformer wires?

No, you don't. The whole reason for grouning the case to AC earth is to prevent a shock hazard if a wire carrying AC mains voltage is to come loose and come in contact with the case or other components. If you put the transformer in a separate case, then by definition there is no AC mains voltage in the amp case. If the case that will be holding the transformer is metal, though, you should ground that case to AC earth.

 

[fc911c]

Ok got it thanks, and that make life simple.


Frank


QUOTE=amb;3132818]No, you don't. The whole reason for grouning the case to AC earth is to prevent a shock hazard if a wire carrying AC mains voltage is to come loose and come in contact with the case or other components. If you put the transformer in a separate case, then by definition there is no AC mains voltage in the amp case. If the case that will be holding the transformer is metal, though, you should ground that case to AC earth.[/QUOTE]

 

[fc911c]

Ok I powered it up and everything checks ok till I check MV on OL and OR to OG. I am getting a very high 175 mv, what do I check first? what might cause this.

The instructions said turn pot CCW to lowest setting to hear the click. I have to turn it CW to hear that?

Thanks
Frank

 

[amb]

Quote:

Originally Posted by fc911c /img/forum/go_quote.gif Ok I powered it up and everything checks ok till I check MV on OL and OR to OG. I am getting a very high 175 mv, what do I check first? what might cause this.

Servo opamp installed? What opamp are you using?

Quote:

The instructions said turn pot CCW to lowest setting to hear the click. I have to turn it CW to hear that?

You will get the click at either end, but if you installed the trimpot in the proper orientation, then you should turn the screw fully counterclockwise before powering up for the first time. Warning -- you could damage the output transistor with too much bias if you power up with the trimpot fully clockwise.

Btw, there is a specific sticky'ed thread for this amp on headwize. Please use that for support, because everything will be in one place, and Alex Cavalli will be able to chime in too. He doesn't normally read this forum.

 

[fc911c]

Hello AMB

OK I had them fully turned the wrong way my mistake it was getting tight the other way and I didnt want to force it. They are installed with the screw on the circle.

How do I check the output transistor?

opamp is the opa2134pa

One other thing I was checking the resistors and most where correct but some of the one's closer to the main caps had costant moving values?

I will check out the sticky also

Frank



Quote:

Originally Posted by amb /img/forum/go_quote.gif Servo opamp installed? What opamp are you using? You will get the click at either end, but if you installed the trimpot in the proper orientation, then you should turn the screw fully counterclockwise before powering up for the first time. Warning -- you could damage the output transistor with too much bias if you power up with the trimpot fully clockwise. Btw, there is a specific sticky'ed thread for this amp on headwize. Please use that for support, because everything will be in one place, and Alex Cavalli will be able to chime in too. He doesn't normally read this forum.

 

[fc911c]

I am olnly getting 15v at the neg test pad and .9v on the pasative?

Frank


Quote:

Originally Posted by amb /img/forum/go_quote.gif Servo opamp installed? What opamp are you using? You will get the click at either end, but if you installed the trimpot in the proper orientation, then you should turn the screw fully counterclockwise before powering up for the first time. Warning -- you could damage the output transistor with too much bias if you power up with the trimpot fully clockwise. Btw, there is a specific sticky'ed thread for this amp on headwize. Please use that for support, because everything will be in one place, and Alex Cavalli will be able to chime in too. He doesn't normally read this forum.

 

[fc911c]

Well I found the problem, but it wasn't all my doing, all my 825 resistors where .825's instead. I looked at the package and I ordered wright looks like who ever picked them at Mouser made a mistake.

I will have to order more as I had just enough. I just cant get an amp fired up, very pissed right now.

I guess you should ck them first, lesson learned. Now I have to see why there is no 15+ on the test pad.

Frank

 

[fc911c]

anybody home?? LOL