Iron Pumpkin(s) and other smaller vegetable animals

[Zen Mod]

in general

in fact, this (Balls of Chrome) situation - that's exactly same "issue" we had with Iron Pre; first gen was made strictly for manual switching of input relays and manual resistive attenuator, so - ZM as creature of habits established in Yore, made relay PSU as common negative, and rotary switch did switching of positive relay rail

then some Lazy Bstrdz started screeching for Lazy Butt solution - We want remote! We want remote! We want remote! We want remote! We want remote! We want remote! We want remote! We want remote! We want remote! We want remote!We want remote! We want remote!

first I issued sort of Guide how to re-work Gen1 Iron Pre pcbs to allow Logic circuitry Governor, to please We want remote! crowd

and then Mighty did rework - to gen2 Iron Pre pcbs, where relays had common positive PSU, allowing implementation of Logic solution for relays and accordingly Idon'tcarewhich Volume option...... simply because majority of Logic circuits are based on low side switches;



final Gen3 of Iron Pre, same approach (common positive), only change to actual manufactured JFets

 

[timkrone]

I like my remote! Thank you!

 

[chromenuts]

Greedy Boy + Old Age = Lazy Boy

When I get to Balanced Iron Pre it will have remote…even if only Muses 😎

Eventually I will build SE Iron Pre with some Slagle Autoformers I nabbed in the swap meet for peanuts…if I live that long

 

[Zen Mod]

you will,

 

[stajo]

After my rearrangement of setup and listening position I have the physical knob 30 cm from my left hand in the armchair. Unbeatable feeling not having to look for the remote but having instant control without even having to open my eyes.

Downside is long balanced cabling as an extra component, but I like it.

 

[chromenuts]

I was thinking ahead a bit today about having to power the Pumpkin boards up and make adjustments while I was working on wiring from the PEM to the donuts.

It occurred to me I need fuses for the PEM.

Did some searching through this and the Tips thread.

Best I can decipher from various posts…I have three 10VA transformers and should divide their total current rating by US line voltage. So 30VA/120V = 250mA?

It seems like I need a fast blow fuse for this application. I know I had some. Searched high and low. Must have lost them in the move.

So I need to order some 5 X 20 fast blow fuses in a few values that would be appropriate.

 

[birdbox]

I used a 250mA fuse, but I used a slow blow fuse. Now I'm curious if I should swap it out for a fast blow. Thanks for the post!

[Edit] With a quick search of the thread, I now see I missed ZM's suggestion to use "Fast and Furious" F250mA. I shall fix the error of my ways.

[Edit 2] Now with the comment below from ItsAllInMyHead, I'm torn 🙂 It's been working great since November, so maybe the lazy fellow in me will just leave it for now.

 

[ItsAllInMyHead]

There's not a great deal of inrush current, but I still like slow-blow in this application. YMMV.

 

[Zen Mod]

So 30VA/120V = 250mA?

yeah, whichever you have

if F goes Dodo, use T

 

[Plott]

Hi,
now - I ordered the remote control for this amp 😍
And now I think to rebuild the whole thing and replace some parts too, and I even think to build new chassi(s).
Well see :😀

 

[chromenuts]

Thinking out chassis and other grounding.

MZM’s Illustrations/Build Pics of grounding scheme from files seem obvious except in my case I have a separate special little Logic PSU board.

The Logic display has “GND” pad and Logic PSU board has “L GND”…it seems obvious, just connect them.

The Logic PSU board “L GND” pad has a trace on bottom that leads to both the holes for mounting standoffs and there will be continuity through my metal standoffs to the chassis base plate.

Since the Logic PSU board ground will have continuity through the standoffs to the chassis base plate where I will be mimicking grounding scheme I see in MZMs Pumpkin build pics, I am assuming there is no need for an additional grounding strap from the Logic PSU board to the chassis/base plate?

I am also wondering if it would be recommended to try and create the chassis base plate “star” ground at the bottom of one of the Logic PSU standoffs with all other grounds straps to Pumpkin boards and PEM?

 

[Zen Mod]

short yellow/green wire from mid pin of IEC to one screw at base plate

that's all you need, and logic PSU is, as you've seen, being cared for though metal standoffs

now, each channel is having "chassis" pad, route thin wire to same screw from line 1 above

 

[birdbox]

Iron Pumpkin "May Day Give-a-Way"