AKG Perception 420 Mod

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joelgurule

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Khron said:
I'm not 100% sure what the news / surprise is - i have three Perception 200's and they're (or rather, were) all surface-mount "already". Well, apart from the JFET and transformer.

Perception 220 inside shots  (identical to the 200 save one capacitor value) - http://audioimprov.com/AudioImprov/Mics/Entries/2013/2/26_AKG_Perception_220.html
Whats the part number for the 670pf smd cap, i orderdled some, but they are too small like half the size of all the smd caps,
 

Khron

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670pF is not a standard value - did you mean 680pF or 470pF?

And SMD ceramics have no markings whatsoever anyway. But you should be able to easily find loads of options at the major component distributors (Digikey, Mouser, Farnell etc).
 

joelgurule

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I'm sorry, I did mean 680pf, I have looked, but the ones I ordered are like micro, maybe 1mm long and the mic takes bigger capacitors, around 2mm or 2.5mm long.. I dont want to order more the wrong size,
 

Khron

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~1mm long (well, more like 1.6mm) sounds like 0603, 2mm long (which the ones in my Perception 200's are) are 0805.

https://en.wikipedia.org/wiki/Surface-mount_technology#Two-terminal_packages

If the capacitance value and the voltage ratings are the same, the physical package isn't all that critical.

You can easily solder 0603 components on to 0805 pads ;) The other way around may be a bit more interesting, but not impossible ;D

0402's (1mm x 0.5mm) could be a wee bit more... fiddly  :-X
 

joelgurule

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thank you, im new at this, I think i accidentally ordered and recieved the 0402's theyvare very small compared to the 0805's, I have the AKG perception 200, which is the mic im trying to mod. yhank you for replying and helping me out
 

Khron

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Well, with a steady hand, some willpower and perhaps a magnifying glass, even those can be usable. Hopefully :)

Just eyeballed some laptop boards (comparing 0402 components with 0805 pads) and yeah, should be workable.

When replacing SMD passives, i usually blob some fresh (leaded) solder onto the ends of the existing component, then heat both ends at the same time with my wide wedge-tip soldering iron. Then i clean the pads with some solder-wick, add a touch of fresh solder to one pad, tack down one end of the new component there, solder the other end, then re-melt and add solder to that first end.
 

joelgurule

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I was gonna attempt to try, but Im not that skilled for a cap that small, I might ruin it and the pcb, so Ill just return, and order the right size, anyway, Im in no hurry...
 

Khron

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I think the only way(s) you can ruin the PCB is if 1) your soldering iron's waaaaaay too hot and/or it's in contact with the pads for too long, or 2) you're being (excessively) "Neanderthal-ic" (or mechanically overly-aggressive) with it ;D

So unless you're using a "fire-stick" (ie. unregulated mains-powered soldering iron running at 400-450C), or the hammer-and-chisel (or pneumatic hammer) method, i'd imagine you should be safe :)
 

JulesP

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Hi, all. Just to make absolutely sure where the cap to be changed ( to a pf 680) is located  on the P420 ( i do not read circuits).
I did change the obviously visible cap on my perception 220 and am quite impressed by it.
And I have 2 p420 sitting here, way too sibilant  for my use on acoustic instruments.
Please, let me know if you can post a pic with an arrow clarifying where the cap is and would be located.
I think it could help a lot of electronic-illiterates  musicians like me.
Cheers.
Jules
 

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Khron

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Any chance you could post a photo of the little "input board", and then we can (hopefully) point out the cap? ;)

JulesP said:
Hi, all. Just to make absolutely sure where the cap to be changed ( to a pf 680) is located  on the P420 ( i do not read circuits).
I did change the obviously visible cap on my perception 220 and am quite impressed by it.
And I have 2 p420 sitting here, way too sibilant  for my use on acoustic instruments.
Please, let me know if you can post a pic with an arrow clarifying where the cap is and would be located.
I think it could help a lot of electronic-illiterates  musicians like me.
Cheers.
Jules
 

Khron

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You're in luck(?)...

https://groupdiy.com/index.php?action=dlattach;topic=63718.0;attach=44866;image
(one of the photos attached on the first page of this thread)

The right side of the board is really blurry, but the cap you want to replace is that light-grey little block, on the upper-right side.
It's in-between those two black-topped resistors saying "1004" on them.

The brown capacitor to the left of those is the 470nF cap coming from the JFET drain, and the trace then goes down to the 33-47nF cap (lower-right) in series with the 6.8k and 560 ohm resistors.

JulesP said:
Hi, all. Just to make absolutely sure where the cap to be changed ( to a pf 680) is located  on the P420 ( i do not read circuits).
I did change the obviously visible cap on my perception 220 and am quite impressed by it.
And I have 2 p420 sitting here, way too sibilant  for my use on acoustic instruments.
Please, let me know if you can post a pic with an arrow clarifying where the cap is and would be located.
I think it could help a lot of electronic-illiterates  musicians like me.
Cheers.
Jules
 

Icantthinkofaname

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Even if you can't read a schematic, it's easy-ish to find the capacitor of you know the capacitance of it. Assuming it's a marked through hole cap.
 

Khron

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That's a biiiiiiig assumption, in this case :) Doesn't quite work in the case of 0805 (or 0603?) SMD ceramic caps though, sadly...

Icantthinkofaname said:
Even if you can't read a schematic, it's easy-ish to find the capacitor of you know the capacitance of it. Assuming it's a marked through hole cap.
 

JulesP

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Hi, all
This is the under view of the AKG  P420 switch box  There is nothing, out of the switches, and their contacts, on the upper level
I hope someone can help me ( I am circuit illiterate , I admit but quite precise at soldering when needed) to locate the cap to be changed to a pf 680.  The improvement on my 220 was very welcome.

Thanks if ever someone can locate this cap, Could help a lot of p420  owners.

Jules
 

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Khron

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[sigh]

Did you even read my post above (Reply #30)?  :eek:

Here, i'll link directly to it:

https://groupdiy.com/index.php?topic=63718.msg912397#msg912397

How is your circuit board any different from the one in the Perception 420, the one i linked to in the post above (which points at one of the circuit photos that's on the first page of this thread)?  ???

[Edit]
Fine, it's a bit different, but it's IDENTICAL on the side that contains precisely the feedback network we're interested in.
So  what's your excuse?  :eek:

JulesP said:
Hi, all
This is the under view of the AKG  P420 switch box  There is nothing, out of the switches, and their contacts, on the upper level
I hope someone can help me ( I am circuit illiterate , I admit but quite precise at soldering when needed) to locate the cap to be changed to a pf 680.  The improvement on my 220 was very welcome.

Thanks if ever someone can locate this cap, Could help a lot of p420  owners.

Jules
 

JulesP

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Hi, Krohn.
Sorry if the pictures did not post, at first.  It took three  times for me to be able to post them., here Image size limitation I sincerely thank you for all advice and clarification . My circuit seems a little different from the source you provided, but there is a grey cap between the two 1004  ones.  I did not want to trigger any impatience, and, yes, I saw your earlier post.
Thanks so much, again, for your patience I am a musician,  composer and arranger, but a true rookie at all circuitry.
I helped my dad with his shaky hands, as a teenager, soldering delicate operations, under his guidance, to help him at a Parkinson that left him without much control towards the end.
I wish I had the time and patience to learn to read electronics, back then...
J.
 

Khron

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You didn't so much trigger impatience, as much as frustration or annoyance, at seemingly ignoring my (i thought) quite obvious and detailed indications :D

But no harm done, all's well that ends well :)

For tips re: desoldering the stock part, see my earlier post on this page. Adding in a pair of tweezers to pick off the desoldered part while the solder is molten helps ;)
https://groupdiy.com/index.php?topic=63718.msg900825#msg900825
 

JulesP

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Thanks for your understanding, Khron!
As much as for this enlightening info.
Truly, I tried to open some images, including yours, here, and it did not work until recently.
Same as trying to upload mine, in the beginning.
Maybe a cookie issue, initially.

In any way, I thank you, as for all others, trying to squeeze-out the best from affordable tools.

Jules
 

negaikast

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Hello All,

Long time listener, first time caller.  Just wanted to say thank you to all who share valuable info to the world.  Bought a used Perception 420 for $80, and ordered some caps from Mouser for $10 (ordered Panasonic SMDs and Wima film and ended up using the Wima).
Spent 20 mins making the “audio hack” and voila.  Another useful tool in the locker!

Have a transformer from FAB arriving soon and that’ll go into my MXL R40.

Then, will replace the capsule from my Miktek CV4 and will try to implant the one from the CV4 into the 420 next.

All I can say is, I’m hooked!

Jake

 

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