18 Watt TMB Build issues

[Reeltarded]

As a lifetime player that is really hard to hear. I am glad your spirits are up and it seems it can only get better from here.

Stupid amp.

[Littlewyan]

Good luck with the op

[guitar-rocker]

You might want to use shielded cable from the coupling cap off the plate of V1-1 (looks like your value is .0022uF) to the pot. Then from the pot to the 470k which could be removed from the board and soldered right on the pin of V3-2. The run as Rock said from the MV to the PI wouldn't hurt if it was a shielded cable too. There is a lot of gain in that side of the amp that is prone to picking up unwanted noise. You could also try the Fender trick of installing a 7 to 10pf 1000v cap from the plate to the grid (V1-1 to V1-2).

[sluckey]

The board in your amp is considerably different from the Ceriatone layout. Do you remember where you got your board and can you post the layout you originally used? Actual schematic would be nice too.

[Spunky99]

I used a schematic and layout that was extremely preliminary back in 2003.
I ordered some new stranded wire as the solid core breaks if you mess with it much. I'm going to just redo and rewire the whole thing and use shielded cable where needed. Chasing gremlins is a waste of time at this point.

The only change from either Richies or the Ceriatone is the layout in a couple of places. Point to point and the schematic is the same.

Off to the hospital now.

[Spunky99]

So since I am going to "redo" the amp, which layout is recommended?

I like blues, hard rock and metal.

I know a lot has changed and some designs are considered better.

Surgery went well I think. I expected pain but there is none.

no feeling at all in the whole hand either. Like a dead man's hand.
I can move the fingers and thumb but can't touch the fingers to the thumb and there is zero strength.

[Richie]

I know what you are going through, I've had both of my hands done for carpal tunnel, and both operated on for Dupuytren's contracture . The numbness or feeling for your fingers or hand will take a while to come back. yes it is scarry. The Dupuytren's contracture was much worse of an operation. The therapy will also help.

A few suggestions. Since your amp has the tube positions more like the Ceriatone, you should follow that as close as or if possible. Also some good ideas were mentioned by others.Guitar-Rocker brought up some good ideas to try when you heal up

The TMB over the years has been redefined and tweaked and changes made. There are different ones all over he internet.
Some involved changing the positions of the V2 and V3.

For an explanation of why. When the TMB was first done, it was in the 18 watt yahoo forum. For someone that suggested they didn't use the trem. And what could be done in place of the trem channel.

The more plexi type channel was used in its place. TMB=(Treble-Middle-Bass). And at that time it was done on an amp that already had the V2 as the PI. As the 18 watt marshall has in its stock form.

As things went on, their were changes in the positions of V2 and V3,and also moved the pre amp MV/gain control to the end of the control panel.More like a plexi layout.

But some still kept the layout the way it was. Many drawings,schems and layouts are out there now, some may also have mistakes that were never corrected.


For your amp, first i'd find a good non microphonic tube for V3. Then Try some different tubes for V1. To get the least microphonic ones.
You can also try using a 270k or 220k in place of the 470k resistor.
And or move that resistor off the board, to the tube pin, and use shielded cable. Lead dress to the PI plate wires can also cause noise problems.

Also look at the Ceriatone values in the tone slope and tone cap values. Usually a 33k and .01 and .022 250pf.

[Spunky99]

Thanks Richie,

I had a carpal release done 25 years ago and I don't remember complete numbness. Patience...
That Dupuytren's contracture is bad, I hope you are doing good now. M Brother still plays clubs after a full release on his fret hand that needs a fuse done and a fused and really bad set of a break on the pick hand. I'm very fortunate.

I'll get out my box of used and NOS JAN tubes and experiment before I cut it up just to see and try to isolate the issue. I'll also get out my ferrite bead kit and experiment some.

My main problem is the solid core likes to break at the solder joints and the square bends too so I chase breaks after chopsticking. I was overconfident when I built this coming off a 3F1 build and VJr mod.

You all have been immensely helpful and I am so happy and very blessed to be where I am with the amp. (it actually works...kinda) Eliminating dodgy wire is the goal in the rewire. Good hand therapy too. Fine motor skills have been minimal for a long time on both hands and my playing has suffered badly.

It will get better.

[Phil_S]

Forgive me for not understanding about solid core. What is it that you are doing to make it break? If you flex it one time to make the bend, it should be fine. No, you shouldn't be reworking those bends.

Respectfully, maybe you'd do better using stranded wire and not be so concerned about right angle bends. If right angle bends are something you really want, look for topcoat wire. It usually has PVC jacket, but comes in 600V rating. IMHO, topcoat is the best of both. The only drawback, if you want to call it that, is that the PVC will burn or melt, whereas the PFTE jacket isn't affected at all by the soldering iron.

My wife had the carpal tunnel release done on both sides maybe 25 years ago (one hand at a time.) The first couple of weeks weren't fun, but after that she's been essentially pain free. The only residual symptom is that her hands get really cold when she goes outside in the winter and they turn pale white if she's not careful to use warm gloves. She favors sheepskin. Do what the doc says about rehab. You'll be better than new.

[Richie]

Their are a few type of the new cloth covered wire. And its not easy to use like the old fender type push back cloth wire.
The old type you didn't need to strip,just push back the cloth and that was it. The new type has a harder cloth with an insulated sleeve or coating. That usually needs to be stripped or use a razor knife to cut the ends. It doesn't push back like the old type. Then if you score the wire while stripping, and bend it, it breaks very easy. Just guessing from the pics it looks like you have the newer cloth type wire?

[Spunky99]

Right Richie, it is the newer type of solid core wire. I use high quality wire strippers but you have to rotate them to cut all of the cloth neatly and the wire is slightly scored. It is a pain in the butt to work with and lifting the turret board is always a scary operation. If you bend the soldered ends a few times it snaps. It isn't the square bends but rather the stripped ends that break right where the insulation is trimmed. A continuity test on all the connections doesn't always discover the partially snapped wire that has enough to pass the low current test and snaps when using a chopstick or moving the bundle.
I ordered qty 8, 25' rolls of different colored stranded 20g 600v cloth covered wire with the plastic insulation under the cloth from Radio Daze.
http://www.radiodaze.com/w6so-20all-8-c ... 6so-20all/


I have 2 combos and 1 head I'm building. So I'll make sure they follow the Ceriatone 2010 layout and schematic. I ordered enough wire to do all 3 plus the 50 watt Plexi model 1986 bass that I have. 4 amps to build while rehabing.

[Richie]

http://www.ebay.com/itm/Vintage-Style-C ... 1c5260a576

this is much easier to use.

[Spunky99]

You crack me up.....

That is exactly what I used...

[Phil_S]

Hmmm. Once again, I don't understand. If you are using real old style push back wire, it does not need to be stripped. Just snip to length and push the insulation to expose the wire.

If you are using the newer type with plastic jacket inside, to state the obvious, you've got to modify your technique so the wire doesn't get nicked. Either you need a different type of stripper or you should live with the frayed ends. One solution to frayed ends is the burn them off with one of those stick wires (assuming it burns) and another is to expose extra wire and use a small segment of heat shrink. I guess a 3rd possibility is to score it with a razor blade (but not down to the wire) before you strip it.

Hey, good luck with the wire and your surgery!

[Spunky99]

Thanks Phil_S,

The reason for the surgery is to correct the fact that my fine motor skills are so poor that it is impossible to do what you suggested with the wire. Using a razor blade is a guaranteed finger slice. So solid core wire is is my nemesis.

Anyway I already ordered the replacement wire.

Thanks for your get well wishes. I can hold a pick now and my new RG655 will be delivered any minute. I'm excited as heck.....