Authentic JTM 45/100 build diary. Clips added.

[Xplorer]

something you might wanna do, once you soldered everything ( but i didn't see that on the old plexis ) is to put this kind of red liquid , like a varnish, ( some more knowledgeable person will tell you the name ) on the top of the soldered turrets, cause with high voltages, you can have small lightnings between turrets sometimes. An old french amp builder told me that , but his amps were sometimes running at 860 volts ! this is to prevent these lightnings, and i think that george uses this.

[VintageCharlie]

The red stuff on the joints is typical for 68 Marshalls,George uses it on his 12000 replica.
Got a package of original turrets with one of the boards i found - i didn't ask for them, the guy just asked if i'd be interested in some. Nice find, but now i have to find a chemist or someone with this specific experience - to know if there is a safe way to clean them. I already thought i'd use harwins, as it's a bit risky to fuss around with the old ones, but the oldies are siply much better built - the flares are nice and round without a single split - harwins split quite a bit and the modern RS stuff is awful in this regard.

[VintageCharlie]

Hi folks, as promissed, here is the simple method i used to cut the RS board material at home, with the simplest tools possible - no fancy saws or expensive equipment. All you need is 2 or 3 clamps (to fasten the material to a desk and the guide (wood block) on top. I'd recommend bigger clamps than the ones i have in the pictures, as the smaller ones might get in your way while cutting. Make sure that the wood block you use as a guide has a straight edge horizontally and vertically, fasten it down very firmly.
I think the best type of handsaw for this is of a type like i used - it has small metal-saw like teeth, but without the "wave", another option that i also tried out and that worked well is a razor-saw - like the X-acto stuff. The razor-saw woul take quite a bit longer than this other type, as the teeth are even smaller.
For my purpose both these saws were perfect as they are only 0.6mm (mysterious metal-saw like thingie) and 0.4mm (razor saw) thick.
It is important that you can push the saw flat to the guide all along the cut length - this way you can get a perfect 90 degree cut horizontally and vertically. The most important is the beginning of the cut where you make the initial "rail" - to ensure that this is "perfect" you could take another small piece of wood, mdf or similar and use it to push the bottom side of the saw firmly against the guide - this way there is no chance for it to slip and cause any problems.
To compensate for little imperfections of the saw blade, change the saw orientation intermittedly, as each blade will have a slight tendency to go into one direction. The cutting is done by holding the saw at a 0 degree angle on the material - the top edge will be perfect without tears and on the bottom the very outer layer of the material will come off only at about 1/3 of a mm - it will become slightly lighter in color - pretty much perfect.

You have to be patient, the cut along the longer 27 hole row takes quite some time - with preparation, measuring, etc. it was about 40 minutes. The shorter cuts are MUCH faster.

All this hassle was important for me because the 2 boards for the 45/100 had to share one common cut that makes up an edge for each of them (due to some imperfections of the sheet) - hence the thinnest circular saw blade (say about 1.5mm) was too thick as the outer edges would end up too thin.

I will post pics of the finished boards in a minute.

[VintageCharlie]

And a couple of close-up pics of the saw.

[VintageCharlie]

Here are some pics of the boards.

[Xplorer]

Fantastic cutting method !
which saw did you use in the end ? 0,6 or 0,4 mm ? where did you buy it ?
it looks beautiful !

[VintageCharlie]

So, my next step is still the turret staking process, but if you take a look on the candidates, you will understand why i consider to be bothered with cleaning the old RS turrets adn use them instead of the new ones. Take a look at the pics below.
I used the keystone swager to check out how each of the three split top turret types compare. (Btw. for this type of split top turrets the keystone swager for a shank diameter of 2.80mm and upwards is the right one. The smaller swager (up to 2.40mm i think) would be problematic. This tool will make nicer flares than the DIY version, as it guides the outer rim of the flare back towards the surface and makes a nice round bend - i think it's worth the investment of a couple bucks (model: Keystone Staking Tool TL-8).

Anyway - from left to right - modern RS, 60's RS, modern Harwin split top turrets.
The only ones not splitting at all are the old ones - slightly thicker metal and maybe a different composition. Judging by the splits there is a differnt metal underneath - something slightly reddish - zinc maybe? and it's coated in tin, i suppose?

I have to find out what metals are the old 60's RS turrets made of to know how to clean them off. I also made the comaprison pics to see how oxidized they are. A firend of mine who is am electritian told me that he considers this as "slight" oxidation adn that they will take solder easily. Despite that i'd like to find out a good way to clean it off. I'm lookinginto some mild acids that attack oxidation and leave the metal itself intact - so there shoudln't be any higher corrosion risk if done right. Any tips regarding this are very much welcome! What do you think? Does the oxidation look bad - is it worth to try to clean them to use them instead of the modern ones. I had planned to stick with modern ones, but the oldies are simply better.

[VintageCharlie]

And a picture of the 60's turret tags and two brand new harwins on the right among them for comparison.

[Xplorer]

i know you'll try to remove this oxydation but if it was me, i'd simply leave it this way. indeed the old RS look great.
i don't know if there was a thin layer that is gone now, ( like on some old string tuners with chrome on it ) leaving the metal under it : then you couldn't get it off as it's just the metal itself. i think that it even looks better this way. i wouldn't be worry either by the soldering , as your electrician friend told you. But anyway, it's nice to wonder.

[VintageCharlie]

I used the .6mm blade - the .4mm would have taken ages to finish the long cut.
Oh, it is also very important to clamp the whole board to a ply or other sheet underneath that covers the whole cutting area - it has to be pressed firm against another surface, otherwise you might experience some rips on the bottom, etc. The way i ended up doing it seems to be bullet(and idiot, like myself)-proof.

[VintageCharlie]

Ok, so a couple of professional electricians (who mainly deal with completely different stuff than vintage amps though) told me that, if the old oxidated turret tags take solder well and it flows well (to make sure it does one just would have to use additional flux, just to make sure), then there is no problem, no risk and also no need to clean them in any way beforehand. They think that cleaning them with some sort of chemicals other than flux during soldering would rather cause problems than the slight oxidation.
One of them tested a turret for me and he said it takes solder very well and it flows great too. The guy who will put the amp together for me said that he thinks it shouldn't be a problem and also some folks on the vintage radio forum said it is safe, as long as they take solder and it flows well; they also said they would rather use the old ones than the new ones that produce these ugly split flares, as that might lead to problems too.

So, after this asking around i'm pretty sure i will go with the old turrets (though i'm still a bit shakey due to oxides, etc.). If anyone who has the experience and thinks that this is a bad idea, please do tell me so, as i'm about to stake the turrets tomorrow.

Thanks and best regards,

VintageCharlie

[VintageCharlie]

Hi guys!

Today i had a couple of hours spare time so i could finally stake the turrets. See the attachment for results. I did my best and took a lot of time to make sure each of them gets home right - i thought i'd screw up many turrets (as this was the first time i did it and i didn't even have the proper equipment - a drill press), but all went smooth. I will post some pics of the "method" and what was going on with the weather (i was working in a shed that has one open "wall") as i started to stake the turrets - it made me feel like something big and important has begun - hopefully noty an epic fail later on
Will stake the filter cap board tomorrow. Need to get a 2.6mm drill bit somewhere, as it needs the 2 extra holes (i had only a 3mm one at home).
Just a couple of the flares split a tiny bit, but otherwise the old RS turret tags just seemed a better choice after my initial tests with the old and new ones. In this particular case it would have been easier to stake the modern ones, as they have a slightly larger diameter, they were a snug fit and there was almost 0% risk of them turning sideways while staking. It was a much bigger hassle with the old ones - to make sure they stay straight (as per BrianH's advice, holding them in place with a fingernail worked nicely - don't cut them before staking turrets -they're a great tool, not just for picking strings!). On the other hand i think it payed off - look at the beautiful flares

Regards,

VintageCharlie

[Xplorer]

NNNice ! it makes me wanna find some RS turrets now. My RS boards won't be as pretty, causes they're damaged, but they'll have a funny vintage style though.

[VintageCharlie]

Take a close look at most originals on amparchives - there's plenty of blemishes on the boards - enlarged holes at wrong or redundant places, scratches, oil and/or flux residue and what not - it's only more authentic with some stuff going on. And if you don't make a straight cut when cutting the boards, it gets even more authentic
I'm relieved the most complicated part (to me anyways, as the soldering will be done by a pro) is over and it went well, as far as i can judge. Would be silly to massacre the board (the fundament for the whole thing) after 1.5 years of search for parts and wait. My arms were trembling when i was doing the first 5 or so turrets, as with each next one i thought that i will screw it up

The Harwin turrets are real nice and it is much easier to work with them (at least in combination with the diameter of original RS board holes). They are also pretty much perfectly identical and will line up 100% straight as soon as you press them in properly. The old RS ones have bigger tolerances from one to the next and if i look at the whole line, i see a couple that don't line up as perfectly as the Harwins. The only drawback to all the modern ones is the type of metal used and the way they flare - some even into the cavity, which i really didn't find all too convincing.
I had a hard time to decide between the two today, just before putting in the first one. I went with the old ones because of how good they flare and because i'm fanatically anal about the "vintage vibe" of this build. I will be a bit more rational with the next one(s), but i'm happy that i went gaga with this one (for now). Next builds will probably be with keystone turrets they stopped using the split top turrets some time in 67 anyway.

[VintageCharlie]

Btw. after this experience i value the great job that BrianH does with his boards even more than before - i don't see how one can do this fast, even with a trained hand. This takes time and patience to do it right. After experiencing the effort behind this, i'd also say that the prices he asks for his boards are very fair, to say the least (that includes cutting, drilling (can't imagine that one if you have to simulate a whole perforated board!) and staking the split tops so that they sit straight). So i now even more consider it a very wise move to get the boards from him.