JTM 45/100 - Build story

[Homebelly]

soldering the back of the pots is really a pain in the ass ... now that it has some solder on it, it doesn't want to melt anymore, to let me solder the buss wire. i should buy a new solder gun, hotter i guess.

Having over heated and screwed up a pot on my first marshall build for this exact reason I have adopted the flying bus option that you see on dumble style amps. I think there might even be a thread buried in here some place where Larry talks about it.
Might be wrong there, but i am pretty sure there is a thread

[Xplorer]

The surface was sanded nicely, and i removed actualy the brown liquid coming out and poping when i soldered some tin. I'm not sure that the flux would let the tin be hot enough to melt. There's quite an ammount of tin on the pots. A proper solder gun would probably do it right. Maybe useless to insist with the one i have.

[VintageCharlie]

I´ve soldered to the back of the pots with an old Russian 100w iron (other smaller irons didn't do it) in a guitar - it would be important that you can get it hot enough and do it fast, this way you don't have to worry the pot might go bad. A bigger tip might be a good idea too. You don't happen to have PEC pots? You're using Alpha, right? PEC have stainless steel on the back - you can't solder on the back of those.

[BoogieEngineer]

Or you could solder a buss through those lugs that are grounded, maybe bend them back a little so that the buss won't get into the other lugs' way.

[neikeel]

Most normal Alpha and CTS type pots pots will take solder if you sand the finish off and use roisin solder and a 40w iron. Exceptions are the PEC pots that are stainless.

Four options:

1) use bus wire soldered to pot like original

2) use bus wire bent to shape like the original back of pot bus, solder it only to the lugs that are earthed

3) bend the earth lugs up and twist them slightly and run a piece of bus wire through them

4) add a solid copper bus rail to the edge of the circuit board

I have used the first three without problems and on an accurate clone or resto would stick with 1 or 2. On my first JTM45/100 and my main 2 in 1 50watter I used number 3.

Not tried 4 as it jsut looks too different!

[Xplorer]

Thank you.
I'll make it original as tin is already on the back of the pots, i'll just get a hotter solder gun.
Mine might be 60 watts, i'm not sure .. 80 watts fine perhaps ? I'll ask advices to the electronic store.

[Xplorer]

ok, this :

NOT A GOOD IDEA !

unless the solder gun is hot enough.

[Xplorer]

But .... i cleaned a bunch of pots and used some spares i had.
The trick is to use just enough solder ( so in any case it'll be easier to unsolder ) , till it sticks nicely on the pot and the buss wire.
after i installed the pots again , sanded in the back, and all nicely in line, i prepared the connections with some velcro and then it was ready to solder. l also realised that when the tip of the solder gun is deeper into the gun, it makes it significantly hotter, and it helped. THAT'S also why i had troubles someimes.

[Xplorer]

.... The inside of an RS pot ! rated 500k but i measured it at about 660 k. The carbon element is quite thick. Other than that, i don't see the extra resistor or something inside, as described sometimes ...
these pots are bigger than the alphas.

[Xplorer]

grounding the input jacks and preparing some other grounds.

[Xplorer]

worked on the boards connections today, preparing it.
before soldering all components i'll have to look for the orientation of the mustard caps.

[BoogieEngineer]

worked on the boards connections today, preparing it.
before soldering all components i'll have to look for the orientation of the mustard caps.

When I was building, if I needed to see anything cosmetically I referred to the pics of amps George built. By the way I don't think the Mustards have orientation. If they had it would have been printed on the cap's body like those axial's.

[Xplorer]

Yes, George's amp is helpful.
Actualy, mustard caps do have an orientation ..

http://www.aikenamps.com/OutsideFoil.htm" onclick="window.open(this.href);return false;

[VintageCharlie]

Now you finally can get to the fun part, huh? Can't wait to see further results

[BoogieEngineer]

Yes, George's amp is helpful.
Actualy, mustard caps do have an orientation ..

http://www.aikenamps.com/OutsideFoil.htm" onclick="window.open(this.href);return false;

Well, thanks for the info! I oriented mine according to George's build, hope he did it right.