Iron Pre Essentials Kits For The DIYA Store - Register Your Interest

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#4,305
hayenc said:
All these years and finally got smoke. One channel came up fine. The other board brought smoke. Using a Variac, so hopefully not too much damage.

Discovered that I had reversed the BD139 and BD140 on the second board. I have some with the higher gain -16 prefix. Will they work? Also, what else should I replace while changing these out? The BC 55x transistors? The IRF150's?
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Lucky you... the very first thing I designed and built, a 12 VDC power supply, around 1980, blew up on me the first time I plugged it in.... I was a Young Master Of The Universe so I didn't need no stinking power switch. I mean, I could not, would not, wire the big caps backwards, huh? 😛

Before that, though, I built a bunch of Heathkits with no untowards behavior. ;-)
 
#4,309
hayenc said:
Just my pride. Over 20 projects since before COVID and my first mistake.

I did discover one LED on the selector board stopped lighting, so more to chase down.

Lesson, don't do electronics when not feeling well.😂
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I think we've all done it a time or two... or three...

Last week, I was in a rush working on a document. I took photos of two specific parts; I zoomed in on the tiny little letters;; I noted in big, bold, red letters to ensure that builders identify and stuff them properly; then I proceeded to mis-stuff the parts. :rofl:

I'm blaming the sinus infection. :joker:

Edited to add - I did send a photo to a friend of my de-soldering tool with the note, "I'm buying my Hakko a present".
 
#4,311
The SMD kit is not the same. From the store page:

“With the new V.4 SMD update, it is important to know that the supplemental / completion kits have changed also. For details, please see post #1 of the Iron Pre discussion thread if you have a V.3 or previous completion kit and you'd like to use it with your SMD essentials kit.”

The build guide also has a more information about how the pcb differs:

https://guides.diyaudio.com/Guide/Zen+Mod's+Iron+Pre+SE/23?lang=en
 
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#4,314
Ok, thanks to ZM and IAIMH another Iron Pre has been hatched!

I worked with the V4 boards and had asked about small parts to aid in setting current through JFETS one the V4 board. See instruction below.

BUT, that ask was LAST week and i was following the general build guide TODAY and everything tested and was set per the specs — and i just noticed i hadn't set the current as noted below.

the iron pre sounds great now, i hope it gets better tomorrow after i go back in for this last tweak.

Assuming someone will tell me to shut everything down if i am courting disaster by missing this last setting.

Thanks for the help y’all!

  1. For V4 SMD Only- Set current through JFETs
    • Set DMM to DCmV.
    • Place probes across R34 and R37 for SE or R40 and 41 for Balanced. You can also use square pads / test points near resistors.
    • Turn P4 and P6 respectively until DMM reads 14mV +- 0.05mV - See schematic.
 
#4,315
dunno, I'm not familiar at all with Store packages, I'm just a guy who drew silly thing


Patrick IAIMH is your Man

though, thinking what I wrote in #4312, just buy whatever packages you can, and if there is any difference, it's trivial

just catalogue what you have in front of you, note tiny difference, and buy with rest of (mostly mechanical) items you'll need
 
#4,316
chedma said:
Assuming someone will tell me to shut everything down if i am courting disaster by missing this last setting.
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No, not at all. With the pots shipped at mid-point, it was likely reasonably close depending on the Idss of the JFETs in your particular kit. However, it's nice to get it 'perfect', just to feel good.
chedma said:
Thanks for the help y’all!

  1. For V4 SMD Only- Set current through JFETs
    • Set DMM to DCmV.
    • Place probes across R34 and R37 for SE or R40 and 41 for Balanced. You can also use square pads / test points near resistors.
    • Turn P4 and P6 respectively until DMM reads 14mV +- 0.05mV - See schematic.
Click to expand...
That is the correct process.
 
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