Newbie with first stupid question

[Lefty W.]

Hello, all. I have just started building a Mission 5E3 kit, my first amp build. I had planned on building this thing as if it is the last amp I am ever going to need, so I'm going overboard in several areas - turret-board, PEC pots, teflon wire, shock-mounted pre-amp tube sockets, etc.

So I'm having a bit of trouble fitting two pieces of 18-gauge stranded wire in the little pre-amp tube lugs for the filament circuit - particularly because I'm attempting to pass the wires through pins 4 and 5. I have crimped and tinned the wire, but I'm still having trouble fitting it in. (Insert any applicable double-entendres here).

Does anyone have any good tricks for doing this? Thanks. (I told you I'm a newbie).

Lefty W.

[Gibsonman63]

Welcome aboard.

I had to use a smaller guage wire for the pre-amp tubes on my build (not an 5E3, but there is one in my future). I don't remember is I used 20 or 22AWG. Based on the current draw, smaller guage should be fine. The lead dress is the critical factor here.

[loudthud]

I use a short length of bare wire like a cut off resistor lead to connect pins 4 and 5 together. Bend the wire into a U shape, insert through the socket terminals and bend the loose ends around towards the other terminal. Crimp the bends tightly and solder. Then wrap the wires that go between tube sockets around that wire and solder.

[Lefty W.]

Thanks.

This may be a difficult way of doing the filament wiring, but I decided to put together the whole wire harness before soldering anything. If everything looks like it fits right, then I'll heat up ol' Weller.

[macdillard]

Just in case you are still worrying about wire size:


American Wire
Gauge (AWG)


18 16 amps
20 11 amps
22 7 amps
24 3.5 amps
26 2.2 amps

[Chuck H]

I've done many filament circuits with 18ga stranded. I hate it. I only used 18ga because I read somewhere that your supposed to. Those were early builds and I'll forever harbor a hatred of wiring filament circuits now even though I've switched to 22ga.

You can take a tip from the vintage amps that used 18ga. On the preamp sockets bend the 4 and 5 lugs to face each other and push them close together. be gentle to avoid damaging the pin contact area by over stressing the lug. This helps a lot. It also helps to have a plan for how you want to jumper the 'other' lead in the twist over to the 9 lug and have it pre trimmed before soldering the 4/5 connection. You probably won't be thrilled with the appearance of every joint but you'll have to get over it. Re-doing it while trying to preserve other connections isn't an option without great dificulty.

I can attest that it's do-able because I did several. But on the last one my phobia had become so bad that it actually slowed progress due to procrastination.

Chuck

[Enzo]

I think super heavy wire like that is a solution in search of a problem to solve. It is way more wire than the amp needs, and gives no benefit to the amp. But it does make assembly more difficult and it gets in the way. The holes on the tube socket are smaller because there is nothing going to be plugged into that socket that needs the current carrying capability of fat wire.

[Bruce / Mission Amps]

I don't supply any stranded wire, only solid core wire.
Also, I don't supply the 18g solid core wire for the filament leads of the preamp tube sockets anyhow.
I think the builders help guide stuff states and or shows to use the supplied 18g solid wire only between the two 6V6 sockets... but even that 18g is over kill. The 20g or 22g wire is sufficient for the tiny 6" of wire travel between the 6V6 sockets.
I never use anything more then 22g wire between my preamp tube sockets, there just isn't enough length to worry about any voltage drops or current loss... etc.

[Lefty W.]

Thanks, all -

Bruce, for some reason I decided to use teflon wire rather than the excellent cloth-covered wire you supply with your kit. My source for the teflon wire gave a choice of two gauges - 18 and 20. I ended up using the 20-gauge for the heaters for the preamp sockets, and the 18 gauge for the 6v6 socket heaters.

The real tight fit was the lugs for pins 2 and 7 on V4, with resistors, heavy gauge wires from the power transformer, wires from the pins to the indicator lamp, and the heaters. A virtual convention on those two lugs.

[Bruce / Mission Amps]

Thanks, all -

Bruce, for some reason I decided to use teflon wire rather than the excellent cloth-covered wire you supply with your kit. My source for the teflon wire gave a choice of two gauges - 18 and 20. I ended up using the 20-gauge for the heaters for the preamp sockets, and the 18 gauge for the 6v6 socket heaters.

The real tight fit was the lugs for pins 2 and 7 on V4, with resistors, heavy gauge wires from the power transformer, wires from the pins to the indicator lamp, and the heaters. A virtual convention on those two lugs.

Yeah, the wires from the PT or pilot lamp to the first 6V6 socket can be tough...but totally doable with any of the wire included.

[koen]

The real tight fit was the lugs for pins 2 and 7 on V4, with resistors, heavy gauge wires from the power transformer, wires from the pins to the indicator lamp, and the heaters. A virtual convention on those two lugs.

What I did was to solder the wires from the transformer directly to the lamp, and from there back to the tube socket. That will make it a bit less crowded near the tube socket.

[Lefty W.]

What I did was to solder the wires from the transformer directly to the lamp, and from there back to the tube socket. That will make it a bit less crowded near the tube socket.

From what I can tell, your method is the more common layout, but I wanted to follow the Mission layout as closely as possible. I figured I was already doing enough changes to this kit as it is.

Anyway, I'm getting close, just need to attach about six of the flying leads from the board, wire up the output jacks, construct my dim-bulb limiter, plug her in, and see if I can avoid killing myself.

[koen]

From what I can tell, your method is the more common layout, but I wanted to follow the Mission layout as closely as possible. I figured I was already doing enough changes to this kit as it is.

I also made some other changes from the Mission kit layout. First I made sure the filament wires on V3 and V4 are also twisted and tucked under the chassis. On the drawing from the kit they are just single wires going straight across from V3 to V4. I also moved the wires that go between pin8 and pin4 on V3 and V4 respectively to go around the sockets. Again, on the drawing they go in a straight line. Not only helped this to decrease the wire spaghetti, it possible could also decrease noises, hiss. Finally (as suggested to me by Bruce), I removed the ground wires from the vol pots to the input jack. Instead, I soldered those lugs directly to the pots body. Again, it decreases the wire spaghetti.

Good luck, and don't kill yourself.

[Lefty W.]

Finally (as suggested to me by Bruce), I removed the ground wires from the vol pots to the input jack. Instead, I soldered those lugs directly to the pots body.

Well, now you've got me concerned that I have set up some ground loops. Because I went overboard and am using PEC pots with virtually-unsolderable stainless-steel cases, I soldered a little jumper wire from the left lug (looking from the back) of the two vol. pots to the brass plate as ground, but I also kept the ground connections between the pots and the input jacks, as per another layout diagram that I have on hand.

I can't for the life of me read a schematic, and I couldn't figure out what the schematic-type symbols on the Mission layout drawing mean, so I followed another layout diagram I had found on the interwebs. Further evidence that I don't really know what I'm doing... I figure I'd better have the paramedics on standby when I flip that "standby" switch...

[koen]

Well, now you've got me concerned that I have set up some ground loops. Because I went overboard and am using PEC pots with virtually-unsolderable stainless-steel cases, I soldered a little jumper wire from the left lug (looking from the back) of the two vol. pots to the brass plate as ground, but I also kept the ground connections between the pots and the input jacks, as per another layout diagram that I have on hand.

I can't for the life of me read a schematic, and I couldn't figure out what the schematic-type symbols on the Mission layout drawing mean, so I followed another layout diagram I had found on the interwebs. Further evidence that I don't really know what I'm doing... I figure I'd better have the paramedics on standby when I flip that "standby" switch...

I doubt you'll get electrocuted from a ground loop

I would either use the connection to the input jacks, or solder the left lug to the pot body, since these are grounded through the brassplate directly. If you have both, you may well have a ground loop.

And when in doubt, ask again here.