hiss on a keywood artist 300

[cielapeute]

hello !
I have changed the capsule of this keywood and the ruslt is that I have a good a and a bade result The sound is dramaticcaly better ! But there is a hiss, which was originally present in the mic before the caspule swap. I would like to know if what component could be the original issue ? thanks for your answers
and I am really happy to have discovered you all.

 

[Khron]

Photos of the PCB, particularly the area where the capsule wires are soldered?

 

[cielapeute]

 

[cielapeute]

here are the photos. for the transparent wire wich is the - of course, I found it odd but it was soldered this way with the original capsule, on the three points. maybe that is where I can change things

 

[Khron]

Yeah, those spots could indeed use some cleaning with IPA (isopropyl alcohol) and some sort of small brush. Maybe start with scraping off the bigger chunks of flux residue with the tip of a pair of sharp tweezers or a small flatblade screwdriver, and then go in with IPA and finish the job.

If you go with the latter option, you can roll up a small ball of cotton wool (or toilet paper, even), grip it in a pair of tweezers, soak that in IPA and use that to wipe those areas clean.

 

[cielapeute]

merci a lot
but is it normal that all the three pins are soldered together as originally ?

 

[Khron]

That mic looks remarkably like this one:

http://recordinghacks.com/microphones/CAD/GXL3000

Schematic:
http://recordinghacks.com/images/mic_extras/cad/gxl3000-schematic.png

 

[Drosselmeier]

sometimes the hiss can happen because one of these parts. in that case its better to clean them up carefully with IPA. but sometimes you will have to change them.
all !
because its impossible to check them if they work or not is impossible without special tech at home, only to trash them and swap for new ones.

 

[cielapeute]

thanks !
I remade the solderings so they are clean now. I resoldered also the oddly three linked pins, as ( even if I cannot easyly understoand a schematic) don't seem to be joined.
but the hiss is still here

 

[cielapeute]

very oddly, the hiss has gone now... without doing anything more.just leaving the mic 48 v on. probably drosselmeirs' explaination is very interesting. thanks !!! I'll see if I can find some of these here, but probably it is easy to order.

 

[cielapeute]

sometimes the hiss can happen because one of these parts. in that case its better to clean them up carefully with IPA. but sometimes you will have to change them.
all !
because its impossible to check them if they work or not is impossible without special tech at home, only to trash them and swap for new ones.
View attachment 134111

thanks a lot ! do you know where I can find these. I don't know how they are called

 

[Khron]

do you know where I can find these. I don't know how they are called

Maybe not in an identical physical form, but they're high-value resistors. I'm partial to TE Connectivity's RGP0207 series, those can be found at the major component distributors (Digikey, Mouser, Farnell).

 

[cielapeute]

Maybe not in an identical physical form, but they're high-value resistors. I'm partial to TE Connectivity's RGP0207 series, those can be found at the major component distributors (Digikey, Mouser, Farnell).

thanks

 

[cielapeute]

Maybe not in an identical physical form, but they're high-value resistors. I'm partial to TE Connectivity's RGP0207 series, those can be found at the major component distributors (Digikey, Mouser, Farnell).

Hello ! I have found the 1go ohm easily on the three, but not the 51m ohms in this very reference. would this one fit ? https://fr.farnell.com/vishay/vr68000005105jac00/res-51m-1w-couche-metal-axiale/dp/3975766?cfm=true or can I take another value in the series you mentioned. If yes, which value ? Thanks !

 

[Khron]

would this one fit ?

Longueur du produit: 19mm

You tell me I'd say it's pretty huge, especially with the ~7mm diameter/thickness...

can I take another value in the series you mentioned. If yes, which value ? Thanks !

47Meg should do just fine - https://fr.farnell.com/te-connectivity/rgp0207chj47m/resistance-couche-epaisse-47m/dp/2805258

Might not be a bad idea to replace all the 51Meg resistors with 47Meg, since they could be used as voltage dividers, and you'll want to preserve the ratios.

 

[cielapeute]

great, thanks !!!

 

[cielapeute]

I am working on 2 paired T bone sc 600 now. I would like to change the two 220uf 16v capacitors for better ones (they have to be small, 8mm diameter and 12 mm high would be great) . I am searching on mouser, which is cheaper than the two others. I found some, but they are of higher voltage... is it a problem. Or chould I take others ?

 

[cielapeute]

these looks good for the size, is it better quality than the original and a fgood idea to swap ? https://www.mouser.fr/ProductDetail/Nichicon/RNE1C221MDN1?qs=j%2B1pi9TdxUYV9osAdnZVyQ==

 

[cielapeute]

these too are the good size https://www.mouser.fr/ProductDetail/Cornell-Dubilier-CDE/227SAK016M?qs=3tP%2BN51vMXfvSx9/

 

[cielapeute]

these are 10 000 hours... https://www.mouser.fr/ProductDetail/Nichicon/ULD1C221MPD?qs=9yI11AV48ZQCaetzdaKtxg==