12xxx Larry Ground

[Strat78]

No variac just per Larry's instructions. I wired the power board so the center tap and the red wire going to the first possitive of the mains cap were easily accessable. Also, I had the red wire from the fuse go to the cap as well instead of the diodes like Vhjunkie showed us. This made it very easy to form the caps without having to lift the board. The reading on the caps got down to 3.6v after a few hours which was great.

Read through this thread if you have not already:
http://forum.metroamp.com/viewtopic.php?f=4&t=8396" onclick="window.open(this.href);return false;
You've had the kit for over a year so those caps will definitely need proper forming. It's easy! You should also pick up a variac to have on hand for other things down the road.

As far as forming the caps, what do y'all reccomend ? I do not have a variac, so I cannot gradually raise the voltage every few hours or so. Will just firing it up on the wall voltage hurt anything ?

So did you do it the way Larry outlined or did you just pull out the tubes and use the variac?

[6burgh]

Hey all,

Just jumping in here as I'm just catching up after being one of the lucky to score one of George's steel chassis. This thread has been a great help, thanks vh junkie, really well done. I'm also posting because I just got Brian H's new boards in. I think the color is going to give this amp some great character. What awesome boards he does, thanks Brian! I'm still putting together the main component board, but most everything else is done. Can't wait to breath life into this thing...

Cheers,

Paul

[Strat78]

Nice work on that! Those brown boards are nice, I have one and will use it on the next project. I love the shrink tubing on the ohm selector wires, but it makes it hard to experiment with different taps. Where did you get that pink wire from? Also, I really like having the jumper wires under the board as well as not feeding all those wires through the turret board, it looks so much cleaner and confident that way. Are you going to form the caps before firing it up? What tubes?

[rockstah]

Also, I really like having the jumper wires under the board as well as not feeding all those wires through the turret board, it looks so much cleaner and confident that way.

my 2cents=
i like to have wires on top as much as possible. makes trouble shooting and tweaking easier let alone having to remove the board for something you could fix in minutes if it were on top.

now sure if you are trying to build a museum piece by all means but if its a player amp and is going to act as foundation for learning amps and tweaking its a different story as far as building goes.... as far as i'm concerned.

Mark

[6burgh]

my 2cents=
i like to have wires on top as much as possible. makes trouble shooting and tweaking easier let alone having to remove the board for something you could fix in minutes if it were on top.

now sure if you are trying to build a museum piece by all means but if its a player amp and is going to act as foundation for learning amps and tweaking its a different story as far as building goes.... as far as i'm concerned.

I do agree... I've got another true "player" amp that's my testing zone for all mods and tweaks. I really set out on this one because I wanted a pure super lead dressed as nice as I can make her... just because I have to feed my OCD somehow!

As far as trouble shooting... test test test. I test every connection before installing the turret board. If there's a problem hopefully I will have found it that way...

Nice work on that! Those brown boards are nice, I have one and will use it on the next project. I love the shrink tubing on the ohm selector wires, but it makes it hard to experiment with different taps. Where did you get that pink wire from? Also, I really like having the jumper wires under the board as well as not feeding all those wires through the turret board, it looks so much cleaner and confident that way. Are you going to form the caps before firing it up? What tubes?

Yup, I'll definitely be forming the caps first. If you'll notice, I've left the lead that connects to the rectifier with a little extra slack, and the PT common is just hanging out there for now. Insert the 100k, and voila, I should be ready for forming. Right now, I'm planning on trying a range of different power tubes... I've got some EL34 =C='s and some JJ E34Ls that I'm going to try. For pre's I'm going to try the late 60's sylvanias that I just snagged from Terry, or I'll use a cocktail that Doug at Doug's Tubes has turned me onto... Tung Sol in V1, Ruby AC7 HG in V2, and a Sovtek LP in V3. As good as I've had in new production tubes.

[vanhalen5150]

Ok, I see what you did with the 2 pre-amp filters. Where exactly did you ground them? Lugs 1 and 2 of the LG layout?

[vh junkie]

Yes, the cap ground going to the turret goes to lug #2, and the cap ground going through the board goes to lug #1.

[vanhalen5150]

That makes sense to eliminate a possible ground loop from happening.

[jimmyride]

So the 5th ground spot is only for the mains filter ground on 12k? I need to know if I have to add some wires there before I install the power board..

[vanhalen5150]

So the 5th ground spot is only for the mains filter ground on 12k? I need to know if I have to add some wires there before I install the power board..

Yes, and if you have a rectifier ground.

[Strat78]

Another great hint from Robert: Your going to be pulling up the power board allot for tweaks, so leave plenty of slack wire so you don't have to un-solder everything each time.

[vanhalen5150]

Another great hint from Robert: Your going to be pulling up the power board allot for tweaks, so leave plenty of slack wire so you don't have to un-solder everything each time.

I do that with all the wires to the board. With the Larry grounds you can always unbolt them as well if needed.

[jimmyride]

One more question... where did you ground the left bias cap on the board? #4?

[Strat78]

Do you mean the cap circled in orange, it is grounded to #2, the one on the right goes to ground #1. The bias caps that are way on the left of the board is grounded to the other bias cap under the bias trem pot.

[jimmyride]

I didn't mean the preamp filter caps circled in orange. I meant the bias caps on the left end of the board. According to the billy batz layout the left one has to be grounded and I'm trying to figure out to which ground spot.