My official JTM45 kit build thread. Pics & CLIPS ADDED

mushmouth · Post by **mushmouth** » Fri Aug 24, 2007 11:49 am

45auto wrote:what a great time! a new build, got the inspiration jamming in the background. we can relate! dude, what color is this one gonna be? i still think your orange avatar is the coolest.

TOTALLY. I'm having a blast, and I set up my build area in the same room as my vinyl collection and turntable for a reason.

This one is going to be the same orange as my George-built '68, as I don't intend to ever get rid of this one. That way I can swap 'em out and still match.

Finished Step 9 last night, with just a few glitches along the way. For starters, in the instructions they show a .1uf cap on the back of the presence pot, but the cap shown is smaller (in dimension) than the cap I got, which also didn't indicate the measurement on it's labeling. I had to go to the sozo site and cross reference the part number. Then, of course, I had the question that's been answered about whether the polarity of this cap made a difference since there is a ring on one end of the cap. I've been assured polarity is not an issue. So far, so good.

The Marshall knobs that come with the kit are too tight a fit for the pot shafts, so I had to take a screwdriver, wrap sandpaper around it, and just slightly ream out the inside of the knob. God that sounds dirty. Once I had that accomplished, I tackled the input jack assemblies. So far so good. Lemme know if anyone spots anything out of place here.

Pics:

Flames1950 · Post by **Flames1950** » Fri Aug 24, 2007 6:00 pm

You're doing a sweet job man!!!!

mushmouth · Post by **mushmouth** » Fri Aug 24, 2007 7:58 pm

Thanks Flames.

Before I start loading components onto the board, my first question is this:

How do you guys get your leads so straight and perfect on the components? I want them to look as close to perfect as I can on the board, so any advice would be appreciated.

Wallace · Post by **Wallace** » Fri Aug 24, 2007 8:12 pm

rockstah wrote:
mushmouth wrote:
Wallace wrote:the line goes towards the tubes (I learn't the hard way )
And yes it seemed to make a difference.

You're build is looking good

Wallace.
Thanks wallace.

But on the back of the presence pot it goes up and down, neither end points toward tubes. lol Does the direction of the cap make a difference on the back of the presence pot?
It doesnt matter. Its a non polorized cap.

toner wrote:
Wallace wrote:I have the same issue with my sozo's.
Overall noise levels in the amp are good (other than the soft "bump" when first switched on under discussion in another thread)

Will turning them round improve tone or do them any damage as (in my case) the amp has been run for about 2 hours with them orientated the same as Mikes.
To be perfectly honest, I don't know how the Sozo polarity will affect noise or tone. I seriously doubt any damage was caused to the caps though.

However, if George, Aiken and Larry say the caps should be that way, I'd have to agree!

http://forum.metroamp.com/viewtopic.php ... 4&start=15

toner wrote:You may want to flip your sozo's around. The general consensus is that the line should face the tubes.

see: http://forum.metroamp.com/viewtopic.php?t=12110

Otherwise, looks great!

novosibir wrote:The stripe is facing to the lead, which is connected to the outer foil.

The outer foil should be connected to the lowest potential, what as for coupling caps are the tube's plates.

Is there nothing explanating on SoZo's website?

If not, then hang him higher

Larry

http://forum.metroamp.com/viewtopic.php?t=12110

You may well be right, but convention round here favours the line towards the tubes.

Wallace.

mushmouth · Post by **mushmouth** » Fri Aug 24, 2007 8:26 pm

George tells me that the direction of the capacitor doesn't matter, so that's the opinion I went with on the presence pot. But since it supposedly doesn't matter, I'm STILL going to point the lines toward the tubes on the board like some of you had suggested. Call me superstitious. lol Can't hurt.

Just want to ask again so it doesn't get buried, how do you guys get your component leads perfectly straight before mounting them?

Wallace · Post by **Wallace** » Fri Aug 24, 2007 8:30 pm

LOL - I felt the same way

re the component leads - I use a small metal rule, press firmly on a table top and roll the leads.

Wallace.

toner · Post by **toner** » Sat Aug 25, 2007 1:03 am

Once the component leads are straight you can hold the component across the two turrets it will connect to and bend the leads up at a 90 degree angle with needle-nose pliers. Then clip the leads down to about 1/8" or 1/4" or so.

I prefer to bend the leads so they are on the inside edges of the turret holes. That helps the component stay in place while you solder. See pic below.

mushmouth · Post by **mushmouth** » Sat Aug 25, 2007 3:31 am

Thanks for the feedback, guys. Half done with step 10 wiring. Finish that tomorrow and post some pics...

I'm jumping ahead to step 12 for a second so there's time for me to get responses, but there is a step that says:

"Route the yellow wire to the dual 16uf filter capacitor. Attach it to one or both of the positive terminals. Attaching to both will provide 32uf of filtering to the output tube screen grids. Attaching only one will provide 16uf. The difference is subtle, but worth trying both ways to decide which you prefer. It's also worth nothing 16uf is the original JTM45 value."

I'd like to hear your opinions from those who've tried both. What's the difference? Can you describe how they're different?

Edit: I posted this as a separate question in the JTM45 thread. It's probably something new builders wonder about, they'll probably never find it in this thread.

mushmouth · Post by **mushmouth** » Sat Aug 25, 2007 2:28 pm

Beginning the day's work by starting the 2nd half of the board wiring. Today on the turntable, we're starting with a little side A of Jo Jo Gunne's self-titled.

Run, Run, Run...

mushmouth · Post by **mushmouth** » Sat Aug 25, 2007 4:47 pm

Finished step 10 and 11, board is now inside the chassis. I'm pretty sure my pulse went up when I saw it sitting in there.

Wallace · Post by **Wallace** » Sat Aug 25, 2007 7:55 pm

more pics!

mushmouth · Post by **mushmouth** » Sat Aug 25, 2007 8:08 pm

Pics of step 10: Wiring the bottom of the ptp board--

Pics of step 11: Wiring the board into the chassis--

mushmouth · Post by **mushmouth** » Sun Aug 26, 2007 1:31 am

Step 12, part 1: Wiring the preamp tubes. This was my favorite part of the whole process so far. That's how sick I am.

Pics:

mushmouth · Post by **mushmouth** » Sun Aug 26, 2007 3:02 am

Step 12 is done. Most meditative hobby ever...

Here's part 2 of step 12 -- Wiring the output tube grids, bias supply and screen grid filter cap. I have the filter cap wired for 32 so that I can try it, unhook the upper one and try 16 and see which one I like better. Thanks to whoever gave that suggestion.

Pics:

mushmouth · Post by **mushmouth** » Sun Aug 26, 2007 1:31 pm

Just a note, i got to step 13 where it talks about which wires have to be routed along the chassis bottom, and changed the blue wires going to the preamp tubes so those now go down from the board, make contact with the chassis, then back up to the socket pins.

Too bad. They looked cooler when they were all defying gravity.