Building an Amp Order of the assembly steps

[heisthl]

A forumite sent me a PM with some newbie questions and one of them was build order. Here's how I responded but there may be better ways that others have come up with.

1.Install the tube sockets
2. Install the transformers
3. Do the AC cord, fuse and power switch
4. Do the rectifier, bias supply,relay supply and filter caps (cap can(s) or
cap board) and standby switch.
5. Wire the output tubes (screen resistors, OT leads, grid resistors etc.)
and the speaker jacks
6. Lay an actual size picture of your board layout in the chassis and wire
all the preamp tubes with an extra inch of wire (use the picture as a guide
to where each wire goes).
7 Wire the heaters
8. Mount all the pots and switches
9. Do the front ground bus
10 Build the board, soldering everything that doesn't get a wire, solder the ground and power leads(leave lots of extra length) to it and make sure all the unsoldered component leads are trimmed.
11. Mount the board and solder on the tube wires from step 6, (trimming if needed) also run the feedback wire from the OT to the board.
12. Wire the pots, switches, footswitch jack and relays
13 Connect the power and ground leads from the board
14. Power it on with no tubes using an extension cord with a 100 watt light
bulb in series with the hot lead. If the bulb goes to dim all is well.
15 Install the tubes and still using the light bulb measure some voltages -
they will all be low but at least you can tell if anything is shorted.
16 Cross your fingers and power up for real

[nickt]

Good approach - but you left out the last step:
17. cry/curse/swear/wimper when it sounds like crap

[dimitris]

Thanks Heisthl,that's really useful.

[Fischerman]

heisthl,
I noticed you do quite a bit of wiring (even the preamp tube sockets) before you do the heaters. What are the reasons for doing the heaters so 'late'? And would heaters-up-in-air (like an old Fender) vs. heaters-on-the-floor (like a Marshall) make a difference when you do the heaters? I usually do them right after installing the trannys but, for me, doing the heater wiring is one the more mudane tasks that I'm not so crazy about...so I probably just wanna get it over with ASAP.

[heisthl]

Last because heaters up in the air are easily touched with the iron while soldering the other tube pins.

[mlp-mx6]

I also do heaters last, and for exactly the same reason. They're in the way!

[Fischerman]

Last because heaters up in the air are easily touched with the iron while soldering the other tube pins.

I just realized that, as luck would have it, the few amps I've built that had heaters-in-the-air all used cloth-covered heater wires and all the heaters-on-the-floor amps had plastic/poly insulation. Your reasoning makes perfect sense.

[Funkalicousgroove]

I go about things a totally different way, Having built 20 of these in the last 12 months, I really think I have it down to a science, It goes together easily, and takes less than 30 hours start to finish this way. I start from the outside walls, and things along the floor and build up and in:


1. Mechanical assembly with screws, threaded stand-off's, tube sockets, Terminal Strips, and ground lugs first. If you install the transformers first how do you get the screws in that are under the transformers? why do you want to build with all that dead weight? leave them out until it's time to wire them so that your chassis can be easily manipulated

Build your boards, and connect all the leads to the boards with an addl 1-
2" of lead just in case, since the screws are already there, hold your boards in place to make sure you get long enough leads BEFORE you clip

2. Install relay supply board, route wires along the back of the chassis- these are the longest runs of wirein the amp. Install and wire footswitch jack, manual/pedal switches, also wire up the voltage regulator and pilot lamp on the "Lamp end".

3 Install Bias supply/ rectifier board, and bias pot. Route wires along the relay switch leads, bind together with zip ties, leaving an area unbound to attach the output of the bias pot to the preamp board later.

4. Install OT and Choke, Wire power tube sockets: Screen grid leads first, plate leads, cathode resistors(or wire if you don't use 1ohm's to ground), pilot lamp power assembly, screen resistors, grid stopper resistors & Bus, attach OT plate leads.

5. Install FET board with Power lead(leave extra length for routing).

6. Route shielded wires: If you are using coax solder the shields to the back of their respective pots, if you are using foil shield Install the pots and ground bus. Wire the input jack.

7. Wire the switches, pots, and PAB relay, Install leads from Relay board grounds to Manual/pedal switches

8. Install the preamp board with flying leads attached, Wire from v1 toward power tubes, then wire the other side of the board starting with the grid leads/ bias supply lead(routing it along the back of the chassis) Wire presence, then master volume. Wire shielded leads for OD Drive and volume, wire tone control leads.

9. Wire channel relay

10 Install power supply board and wire (all leads should be in place by this time and just need to be attached) and wire stand-by switch.

11. Wire Up OT Secondary (This step can take place anytime after v2 and v3 are wired with plate, grid, and cathode leads) Impedance selector, and speaker Jacks.

12 Mount PT and wire B+, Bias Supply, Grounds, and filament LEads.

13. Install twisted filament leads

14 Install power cord and wire Power switch, and fuse holder ( I don't EVER wire the death cap, if you choose to it is your perogative)

15 Install fuse

16. Check all Grounds, and leads for continuity, take your time and go over each lead to make sure it is wired correctly.

17. Plug into a current limiter or variac and fire it up

18 If everything is good, fire it up at full AC and check voltages

19. If everything is good, Install tubes, bias, and give her a listen!


More than 50 ways to skin a varmit far as I can tell!

[Fischerman]

If you install the transformers first how do you get the screws in that are under the transformers?

One thing I took extra care/time to do in my build (which is in a Weber Bandmaster Reverb chassis) was make sure no screws/nuts were obscured by anything. Every component in my amp can be removed without having to get under anything else to get at screws/etc. I could pull either tranny...the choke...any circuit board without even having to loosen anything else.

So as the Murray says in Caddyshack..."so I got that going for me." (I think it was Murray's line).

[angelodp]

I am that newbie and thanks to all for the input. Very very helpful

Ange

[Funkalicousgroove]

There wil be no money, but on your deathbed you will recieve total consciousness...... So I got that going for me, which is nice.

[heisthl]

Funk - That's a great build order.
Your steps encompass a "real"Dumble build with the extra board under each board assembly which means you have to wire the leads to the board first. On a non "real" Dumble build you can do the other end of the leads first and attach to the board second the only difference is it's easier to get the lead length right. Good point on the transformer weight.

[Funkalicousgroove]

There are many ways to go about it, I don't think Dumble did ANYTHING the easy way!

[briane]

well, i'll bite...my order is a bit more like funks...from outside in, and from high voltage to input.

1) layout all parts
2) drill & shape chassy
3) paint and label said chassy (I do my own)
4) build board and populate
5) eic and pt
6) install tube sockets, standoffs, tube attached components
7) fuse and heaters
wire power switch to fuse
9) first fire up, orient OT for least humm, install and wire (use current limiter)
10) install board, add minimal wires as will be needed to board (grounds, power tube feeds, etc..)
11) install front panel controls, standby, wire as much as possible
12) install wires on tube sockets
13) run socket wires to board, do input wiring
14)run board wires to front panel
15) wire board to power tubes
16) power that sucker up, with current limiter
17) if all looks good, hook up to variac and go, go, go!
18) build head cab

yep, 20-25 hours for assembly....and I maybe have another 10 in punching the chassy, painting, labeling, shellac, and making it pretty. and the cab, well thats its own project...

[heisthl]

Good approach - but you left out the last step:
17. cry/curse/swear/wimper when it sounds like crap

I'm not familiar with that step.