[Danthrax]

Hey does anyone know the pinout on this pot http://www.mouser.com/Search/ProductDetail.aspx?R=RV122F-20-15F-A50Kvirtualkey14860000virtualkey313-1240F-50K Is 1 the left pin closest to the knob? And I was also wondering what the pinout is on the power it has 3 tabs but I thought it was just positive and ground? http://www.mouser.com/Search/ProductDetail.aspx?R=163-4305virtualkey11180000virtualkey163-4305
 
Thanks

 

[c12mech]

Quote:

Hey does anyone know the pinout on this pot http://www.mouser.com/Search/ProductDetail.aspx?R=RV122F-20-15F-A50Kvirtualkey14860000virtualkey313-1240F-50K Is 1 the left pin closest to the knob? And I was also wondering what the pinout is on the power it has 3 tabs but I thought it was just positive and ground? http://www.mouser.com/Search/ProductDetail.aspx?R=163-4305virtualkey11180000virtualkey163-4305
 
Thanks

 

There is a good pin out and explanation of the pot on tangent's webpage.  Best thing I can say is if you are looking at the pot from the back, the right pins, front and back, are the inputs, the middle the outputs, and the left are ground.  I hope that makes sense.
 
http://tangentsoft.net/audio/pancomp.html (Best explanation I've found yet)
 
As for the power plug, there are 2 ground pins.  The datasheet  shows them as pins 2 and 3.  The easiest way to figure it out is to check your power supply to see if the center is power or ground.  If it is power then the center pin on the plug is where you want to connect the 48v line to.  Use a multimeter to check continuity between the pin in the plug and the pis on the back.  You can use either of the other 2 pins for your ground.
 
Like I said, I hope all that makes sense.
 
Bryant

 

[RedLeader]

Yea, I realized I'd have to bust out the meter, I just wasn't sure what the values I should be looking for.  I checked the sources first, got 12.62 on the good channel, 13.37 on the bad.  Both drains held at 47.9, and the good channel gate was 17.2.  However, the voltage on the bad channel gate was "shut off multimeter and make the speakers plugged into the same powerbar buzz".  That's on the MOSFET I already replaced, so I'm continuing to dig.
Tube measurements - 1.3v(bad) 1.4v(good), 12.85v(bad) 13.61v(good)
 
Quote:

 
I can only think that maybe some of the resistors are not at their correct values, or maybe the coupling cap is open... . Measuring the voltages at the tube plates and grids, as well as MOSFET gates and drains could point you in the right direction. Both channels' measurements should be the same (or very close). IIRC, for a 12AU7 version, plates sit at ~27 V, grids at ~ -1 volt, MOSFET gates at ~ 17 volts, MOSFET drains at ~48 volts and MOSFET sources at ~ 12 volts.
 
cheers!
 
 

 

 

[Amatsu]

I've a question about the tube pins. In a 9-pin tube socket for 17EW8 which one is pin 1? Looking at the schematic http://img338.imageshack.us/img338/2543/17ew8millettstarvingstu.jpg I'm a little confused because they are not in order, 6 is next to 1 for example. Thanks.

 

[tomb]

Quote:

I've a question about the tube pins. In a 9-pin tube socket for 17EW8 which one is pin 1? Looking at the schematic http://img338.imageshack.us/img338/2543/17ew8millettstarvingstu.jpg I'm a little confused because they are not in order, 6 is next to 1 for example. Thanks.

That's because it's a fully-schematic representation, but completely accurate for the design.  However, the physical reality is that every 7-pin tube is going to begin on 1 and end on 7.  Likewise, every 9-pin tube is going to start on 1 and end on 9.  Look at the datasheet for the tube to be sure.  I can't help you with the 17EW8, but TDSL or Pete's pages or many other resources can provide a datasheet, I'm certain.
 
As for the 19J6, just to use as an example:
http://www.diyforums.org/SSMH/SSMHtubes.php
You can see the physical pin arrangement with a schematic representation of the elements inside the tube - this is typical for all tube datasheets.  Further, the pin orientiation is always shown as if you were looking underneath, up at the bottom of the tube.  So, to reverse that - if you were standing over your amp and looking down at the tubes and sockets that were upright - then Pin 1 will be on the Right and Pin 7 (9) will be on the Left.
 
Hope that clears it up for you!

 
 

 

[Amatsu]

Thanks tomb, that's very helpful.

 

[Danthrax]

I thought someone a few pages back said it was clockwise from the opening for 12au7 So the 1-9 in order starting at the gap in the pins when looking from the bottom.

 

[chrisw302]

My Starving Student. This is my first diy audio project and my first tube amp of any sort. Gotta say that it sounds pretty nice. Thanks to Pete and all who contributed here.This thing is just great.
Chris.

 

[Danthrax]

Ok so for those with metal cases how did you perfectly isolate the heatsink and mosfets from the ground? No matter what I tried I still got beeps from the multimeter between my mosfets and my metal box... I ended up just using double sided tape and some JB Weld but it seriously looks like crap.

 

[Danthrax]

Quote:

There is a good pin out and explanation of the pot on tangent's webpage.  Best thing I can say is if you are looking at the pot from the back, the right pins, front and back, are the inputs, the middle the outputs, and the left are ground.  I hope that makes sense.
 
http://tangentsoft.net/audio/pancomp.html (Best explanation I've found yet)
 
As for the power plug, there are 2 ground pins.  The datasheet  shows them as pins 2 and 3.  The easiest way to figure it out is to check your power supply to see if the center is power or ground.  If it is power then the center pin on the plug is where you want to connect the 48v line to.  Use a multimeter to check continuity between the pin in the plug and the pis on the back.  You can use either of the other 2 pins for your ground.
 
Like I said, I hope all that makes sense.
 
Bryant

Thank you.

 

[chrisw302]

Quote:

Ok so for those with metal cases how did you perfectly isolate the heatsink and mosfets from the ground? No matter what I tried I still got beeps from the multimeter between my mosfets and my metal box... I ended up just using double sided tape and some JB Weld but it seriously looks like crap.

The heat sink does not need to be isolated from ground, only the mosfet. The mounting kit for the mosfet comes with an isolator for the mounting screw to keep the screw from actually touching the mosfet and the therafilm isolates the body of the mosfet from the heat sink. My heat sinks are soldered directly to the metal case.
Hope this helps.
Chris.

 

[the_equalizer]

 
Quote:

Yea, I realized I'd have to bust out the meter, I just wasn't sure what the values I should be looking for.  I checked the sources first, got 12.62 on the good channel, 13.37 on the bad.  Both drains held at 47.9, and the good channel gate was 17.2.  However, the voltage on the bad channel gate was "shut off multimeter and make the speakers plugged into the same powerbar buzz".  That's on the MOSFET I already replaced, so I'm continuing to dig.
Tube measurements - 1.3v(bad) 1.4v(good), 12.85v(bad) 13.61v(good)
 


 

I didn't quite get what the problem with the voltage was in the "bad channel" MOSFET gate. But if it's really off from the correct value, I'd check the connections involving (referring to the diagram's upper channel part numbers) R2, R3, R4 and C2 as well as check the resistor values with a multimeter (disconnecting at least one end of each resistor from the circuit).
 
cheers !
 

 

[RedLeader]

Resistor values check out fine, but I don't have a meter thats capable of checking capacitance.  What I meant was, the voltages are off by about 0.6v or so, but when I tried to check the voltage on the gate of one MOSFET, the meter shut off, which I assume means some kind of ground fault. 

 

[Danthrax]

Ok so i have a problem I get power, leds light up, the tubes have some red showing like its heating up but I have no sound coming out. The heatsinks for the mosfets also get warm. Are there any possibilities for a fix that jump out at you right away? Maybe it is the optional resistors at the audio inp ut? Should I be hearing complete silence when nothing is plugged in I was expecting some form of interference or something.

 

[nullstring]

Quote:

Should I be hearing complete silence when nothing is plugged in I was expecting some form of interference or something.

Wait, are you telling us you have nothing plugged in?
 
Yes you should be hearing silence with nothing plugged in >_<.