Getting a head of myself - Marshall 2204 JCM800 inspired build

[kuDo]

After a lot of back and forth, I now came up with a layout that is a lot more satisfying.

Looks good! The board for the loop is a good idea!

There still seem to be a couple of long leads, but I thing that will be unavoidable.

There always seems to be a few long runs you can't avoid. Only two jump out at me on your new layout. I think both can be fixed by using shielded cable for the runs. Specifically, I'd use shielded cable for the run to the top of the master volume and on the run from the center wiper of the volume pot to the grid. You may have been planning on doing this already.

Mike

I am currently looking into what wires I will oder. Your idea of shielded cable is a good one. I’ll keep it in mind

[kuDo]

Provided there’s plenty of over voltage capability with the rectifier, I don’t see the point of fusing both HT winding phases?
A single HT fuse in the CT return to 0V seems plenty for this design to me.
If you’re determined to stick with it, then put the bias feed to the hot side of the fuse; it would be bad for that fuse to blow and take out the bias supply, whilst leaving the other phase supplying the HT.

I have chosen to place two fuses, even though the diodes are rated to handle enough power.

In de unlikely scenario that two opposing diodes short out, a fuse in the CT return will not protect the transformer. The two diodes would short circuit the winding and it would burn out.

I will however think about your remark about the bias supply. Thanks!

Merlin makes a pretty good case for using two fuses on the ac side of the secondaries on his site here:

http://www.valvewizard.co.uk/fuses.html

Having one leg of the rectifier short out does seem like it would send current through the secondary and bypass any sort of fuse on the center tap. I'm using this fusing arrangement on all my new build now.

Mike

This website is what I used for the fusing setup I am planning to use. Pretty cool website, he has got!

[kuDo]

Next step in my amp building journey, creating an anvil tool for building the turret boards.

I bought a couple of parts that can be used to set the turrets. I think these are are best used in conjunction with a drill press. But since I haven’t got one I decided to create a simple low-tech helper. A flatbed to keep the board straight and a sturdy mount for the bush that will keep the turret in place during the tapping until it is secured.

I tested it on 1 turret so far and it worked a treat. In my upcoming holidays I while attempt to create the boards a designed earlier. Wish me luck...

[ChopSauce]

Simple yet effective...
(an hole into the board and it would find its place with all sort of similar little helpers hanging around my workshop)

[kuDo]

Simple yet effective...
(an hole into the board and it would find its place with all sort of similar little helpers hanging around my workshop)

Yes, it so funny that before you even start the build, you already have to be creative.

[Colossal]

Very cool!

[kuDo]

Well, Christmas came right on time this year.
I ordered the first half of parts that I would need to make the JCM reality. I ordered al these part at Tubetown Germany.
The showed up two days later right in time for the holidays.
Everything I order was accounted for. Which I am really happy about. Some good service from the folks of Tubetown.

I also started the design of the faceplate for the amp in Adobe Illustrator, so I can have a vector based artwork to cut and print from.

I will keep you guys posted as a proceed!

[xtian]

Yum yum! I love parts.

[kuDo]

Yes, they are the best part

[ChopSauce]

How lucky you are! You also had Goldbären...

Next time I'll have to order more parts...

And yes, TT service is pretty efficient.

[kuDo]

Ha ha, yes!!! Ans some delicious Schoko-reis

All the electronical parts I will however order from Mouser. Quite curious of what choco goodness the will send me. Looking at their name, it’ll probably be cheese.

[ChopSauce]

They just sent me the holes of the cheese...

[pdf64]

Yes, TubeTown service is excellent, the TT Santa made an early delivery for me on Christmas Eve
I thought I better get my order in before the brexit transition period ends, in case of increased customs taxes and delays in the event of ‘no deal’. However, despite common sense being desperately rare in government, that particular disaster has been averted.
TTs product range seems to be getting ever wider, check out their pedal stuff.
Likewise their range of electronic parts, with prices tending to be better than Mouser etc. eg Bourns pots, Mallory 150s.
I’m not a ‘sweetie’ fellow, so my wife got the Haribo and Schoko-Reis bar, thought every time she mutters that it’s the most overpriced sweets ever

[kuDo]

Hello everyone,

Here for my first post this year. So happy new year everyone!
Thank you for your replies so far. The last ones were quite funny

After I unpacked all my newly delivered goodies, I have been working on a couple of things.
The next step in the process would be to plan where all the parts would go. I already thought of that when I drew the first layout that I posted earlier, but now with the actual parts there is always something you didn't foresee.

I decided that I would like to have a drill and punch drawing. A guide that I can put on the amp chassis when the time comes for me to actually start drilling and punching holes.
Making this guide forced me to really think hard of where things would be placed.

First thing I noticed was that the layout I had drawn earlier was wrong. The dimensions of the chassis was set in the software I drew it with, but the software didn't re-compute the linework. This meant that the actual size would be smaller than the size I had been working with earlier, Yikes!
Thinks would become a little more cramped for space.

Next to the size issue, placement of the part would also be dictated by the transformers. These are mounted flat against the outside of the chassis. This meant that a couple of parts I had planned to be on the other side of the transformers couldn't be attached because the transformers would prohibit the placement of the bolts.

After a lot of puzzling I finally came up with the schematic that is attached joined with a drill and punch drawing I drew in Adobe Illustrator.

Now everything has it's place in the chassis I can start to make the turret boards using the tool I created.

[kuDo]

Forgive me, Forum, for I have sinned. It's been...awhile since my last post.

I have been working on the turret boards. They have all been finished.
I did have to order some extra turrets during the process, because apparently I didn’t order enough.
Also I have received the front and the back plate that I designed in Illustrator. The fine folks of Tubetown made these for me after I send them my design files.

Then after that I thought it would be a splendid idea to break myself the metacarpal of my pinky.
So it took my a while to finish the boards. But eventually I got there.

Today I worked on the chassis. I will report back here once I have made some decent progress.