Nomad Mods - A Visual Reference

[nomad100hd]

i sold my nomad channel switching problems, i'm very happy to see my push to self mod had kept going strong. I do miss my mesa, it's tone and have grown tired of both the weight and sound of my MTS head.

 

[DirtyFrank]

Thanks Pat,

- Never had a problem before the Mods and the amp got wacky immediately after the mods. My biggest fault is that I did all the mods at once without checking the amp after each mod :/

- The tubes were allegedly replaced right before I bought it and the Mesa store here in Hollywood was familiar with the seller and the amp.

- I did no bias mods but I did do :

The "remove 2 caps mod"
The Reverb Mod
The NFB Mod
The parallel to series fx loop mod
The 47pf cap mod which I reversed

Since reversing the 47pf cap to stick the amp now fires up, sounds great, heats up and dies. Then I flip the standby and it comes back for a few seconds. The sound starts crackling and sputtering and the power light flickers to the crackle and sputter of the signal.

When you say to slave the amp into another, can I do that with an orange tiny terror that doesn't have an fx loop?

While its working it sounds awesome so I have to be close...

 

[the recluse]

When you say you reversed the 47pf cap, did you use a polarized cap in that position?

Beyond that, did you use caps that were rated with a high enough voltage? Because it's something that comes and goes and is affected by the standby switch, I'm wondering if it's a bad cap somewhere.

 

[thelastleroy]

What I meant by "slave" a different amp into your nomad means basically a line level signal going into your effects return jack. If you don't have anything to try this with, no big deal. I thought it might help to identify the part of the amp that is misbehaving. If you have some spare tubes, I'd try swapping out the tubes one at a time (pairs for the power tubes). It doesn't hurt to try, and it won't cost you anything.

 

[Tommy_G]

If you clipped the caps in the power output section, which are sometimes used to prevent ultra high freq oscillations, maybe yours fell victim to oscillation and this is why its acting up. I don't know this for sure, because I've never had the problem, but seems to me this cap clipping thing brings this sort of behaviour on.

 

[Tommy_G]

double post.

 

[Monsta-Tone]

This is really cool! You guys have me totally gassing for a Nomad 55 combo now!
I just sold my Maverick and was looking for a replacement with much more gain.
You just might have saved me from buying a Mark V! :lol:

Frank,
With the Loop mod, the Send jack now has all of the signal passing through it.
Try using a short patch cable from the Send to the Return jack.
If this fixes your problem, put the 47pf cap back in and replace at least the Send jack, preferably both.

Also, double check your solder connections between wires 1 & 2. A bad connection here would definitely cause you to loose signal.
I would be willing to bet that it's the Send jack though.

Replace the jack with a high quality Switchcraft.
Send: http://www.tubesandmore.com/scripts/foxweb.dll/moreinfo@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?item=W-SC-12A
Return: http://www.tubesandmore.com/scripts/foxweb.dll/moreinfo@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?item=W-SC-11

 

[Monsta-Tone]

Crap!
I was just looking at pictures of the Nomad guts.
If the patch cable works, you might have to order a jack from Mesa to replace the Send jack.
The Switchcraft jack would be really hard to install since these jacks are board mounted.

Another great alternative would be to install a switch that bypasses the switching mechanism in the Send jack.
This switch could easily be installed where the Mix pot was.

I am pretty sure (don't have one in front of me) that this is what the switch would look like (using a simple 2 position SPST switch)

Pin 1 - wire 1
Pin 2 - wire 2
Pin 3 - wire 3

Basically inserting a switch where the pot used to be and wiring it exactly the same way.
One position of the switch would tie the wire (wire 3) leaving the Send jack, before the switching mechanism to the wire (wire 2) that goes to the recovery stage of the Loop.
The other position would make the Loop work exactly as if you had not connected wire 3.

This would be a great way to not have to replace the jack.
If I got this wrong, someone please let me know.

 

[the recluse]

Having done the parallel to series mod on my Nomad 100, I can confirm that you need to run a patch cable from send to return if you are not running effects in your loop. I installed a Push/Pull pot so I can do Series or Parallel so I don't need a patch cable when I'm not running my normal effects loop stuff.

 

[DirtyFrank]

That's it! The patch cable works!!

I was starting to think it was a tube but this is obviously the culprit.

Thanks guys!!!!

Frank

 

[boogieman2012]

I did the FX Loop Mod to 47pf, and the mud mod, and it just woke the amp up, sounds much better.

Very easy to do with good results.

Last mod forme is swapping out the black shadow and putting in a vintage 30.

This amp sounds killer thru my 4x12 with vintage 30s.

Could you please post your thoughts on how it sounds with the vintage 30. I'm planning on doing speaker swap on my 2x12 100. Was thinking of trying one 30 and one black shadow.

 

[Jonom]

Hello I am new to the forum and just completed all the mods but the Parallel to Series effects loop mod. All that I can say is my nomad 55 sounds incredible! Thanks to all for these mods!
And now for my question about the parallel to series mod:
I want to install a push pull pot, I can see from the schematic that it needs to be a 25k audio taper. My question is how should it be wired to go from series to parallel? Also I'm hoping that I don't need to run a patch cable from the send and return jacks after the mod to get signal.
Thanks!

 

[the recluse]

The push/pull pot eliminates the need for a patch cable. If you are not running any effects through the loop put the loop in parallel mode with the mix control all the way up.

You may have trouble finding a 25K push pull pot (I did). You can use a 50K pot and shunt a resistor of roughly 50K (a 47K or 51K should be fine) across terminals 1 and 3 of the pot.

The wiring for the push/pull is to leave the pot as is in one position, and in the other position directly connect leads 1 and 2.

You would leave lead three attached to the terminal of the pot. Disconnect leads 1 and 2 from the pot and attach each one to a separate common pole of a DPDT switch. In one position of the switch, run leads from the pot to one side of the DPDT switch so that in that position the pot is engaged. In the other position of the switch, run a jumper across the poles so that 1 and 2 are connected in that position and 3 is not in the circuit.

I hope that makes sense.

 

[Jonom]

Thanks Recluse for the info. As soon as I get the parts I will replace the stock part with the push pull potentiometer. Looking forward to hearing this mod too!

 

[NomadExpress]

Updated the NFB mod with a parallel resistor/pot variation and added the FX loop patch cable tip.

Thank you for the continued learnings.

 

[Jonom]

What would be the best tubes for the nomad 55 post mods?
I currently have jj audio el34s for the power amp section and electro harmonics 12ax7's in the pre-amp section, with a Phillips 12at7 in the last slot.

 

[Jonom]

Hey Nomad express,
Your mod looks great, Love the pics! I already did the 1mega ohm push pull pot variation or else I would give it a whirl...

 

[Jonom]

Just installed the push pull 25k pot and wired it up for the series or parallel effects loop mod. Took out the old pot and replaced it with this mod and it sounds much better in series. I love the option of being able to still use the pot for mixing the dry signal with a wet one and I hooked up a multi effects processor to make sure everything was in working order. But the amp sounds so good now with all the mods that I think I won't even bother to use outboard effects! Thanks again to Recluse for the help in wiring up the pot! All of these mods I highly recommend to all Nomad users.

 

[the recluse]

Glad it worked out. I wasn't sure my description of the Push/Pull Mod was clear enough.

 

[Jonom]

Oh yeah dead on. Thanks again!