D47 Fet New Body Style PCB now available

[globalpurpose]

What kind of threadlock do You use , sorry for my bad english , when i try to google it i have many different stuff shown

 

[Rob Flinn]

What kind of threadlock do You use , sorry for my bad english , when i try to google it i have many different stuff shown

This stuff.

 

[globalpurpose]

as i can see on the parts in the original manual , there is no washer inside between the body and Hex screw , i think it would be a good idea to put one to minimize vibrations transmission . What do You think ?

 

[globalpurpose]

I emailed Jenny at Shengyin Electronics ([email protected]) and have 2 U47FET bodies on the way with a pair of M49 bodies & shochmounts that according the drawings she provided will work with Poctop's boards. It took a bit of back and fourth, but I'm on for 4 bodies at around $125 each with shipping. View attachment 126590

You mean 125 $ each including shipping ??? very nice !!!

 

[materials to outlet]

You mean 125 $ each including shipping ??? very nice !!!

Yes, though the shipping was covering 4 bodies and a couple shock mounts, so I don't know what it would cost for say one body shipped.

 

[EarthTone]

Now sorted.

The recommended grounding through the xlr is not good. I used another wire from the pin 1 to ground the metal stand offs properly, thanks to TLRT's advice & now have a nice sounding mic.

I’m glad you got it sorted. I borrowed an idea from someone else near the the beginning of this thread and used some copper tape from the xlr ground lug to the body itself. So that is another way it could be done. My two are noiseless and sound awesome. So glad for this boards set and Dany’s fine capsules.

 

[neowalla]

Some build pics:
View attachment 104980

Thank you!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[klem]

a small addendum to @vinylwall 's excellent post: here are two part numbers for the two hex standoffs between boards:
Würth Elektronik
Manufacturer #
971170151
and
971250154

mouser has some mislabeled items, but these two are verified to work with the posts that came with the mic body i have, just not color correct

 

[neowalla]

What timing! I just ordered this from Amazon:
https://www.amazon.ca/gp/product/B07FMV5RMG/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1
I see the ones from Mouser are 17mm long and this assortment has 15mm and 18mm. The 18mm ones should be close enough. I can always grind off a millimetre if I really have to.
I'm putting a K47 from Arienne Audio in this one. Looking forward to it. That Shuanyang (or whatever) body looks exactly like the Neuman reissue. I bought one off Aliexpress and though a bit pricey, it is a really nice mic body.

 

[neowalla]

Hello everybody, I am using the UTM 0547F transformer for this build and have a question about the wiring. The yellow wire on the attached diagram looks like it connects to the core, or the laminations of the transformer. Is this a ground connection? If no, then where would it go in this circuit?

 

[neowalla]

I built this thing and I have no output. I'm not even sure how to go about troubleshooting it with the hiZ PCB soldered to the main PCB by way of the switch PCB and JP1 and JP2.

 

[Kelvin Zero]

I built this thing and I have no output. I'm not even sure how to go about troubleshooting it with the hiZ PCB soldered to the main PCB by way of the switch PCB and JP1 and JP2.

I've had terrible trouble with my 47 FET builds due to counterfeit or dodgy FET's.
This component tester as suggested by @rock soderstrom has saved me so much time
https://groupdiy.com/threads/cheap-component-tester-oscilloscope.86503/post-1142647

 

[neowalla]

I have that tester or one just like it from Aliexpress. The FETs and transistors for this build were bought from Mouser. I don't know if that is any guarantee against counterfeits but I admit I did not test them prior to installation.
I did replace C4 after finding it checked bad. It was a vintage "Kondur" cap salvaged from a piece of industrial equipment. It looked like a styro to me so I pulled it. Go figure, it's bad. I replaced it and the mic output audio for a couple brief seconds, then faded into silence again so I am back to square one. In the future I will not build any mics with these stupid round PCBs that have to be soldered together. It makes separating them for repair extremely difficult.

 

[vinylwall]

I have that tester or one just like it from Aliexpress. The FETs and transistors for this build were bought from Mouser. I don't know if that is any guarantee against counterfeits but I admit I did not test them prior to installation.
I did replace C4 after finding it checked bad. It was a vintage "Kondur" cap salvaged from a piece of industrial equipment. It looked like a styro to me so I pulled it. Go figure, it's bad. I replaced it and the mic output audio for a couple brief seconds, then faded into silence again so I am back to square one. In the future I will not build any mics with these stupid round PCBs that have to be soldered together. It makes separating them for repair extremely difficult.

My build notes on Page 3 of this thread specifically tell you how to assemble these and still be able to get them apart later if need be.

 

[neowalla]

Yeah I see your note now. Naturally when I was building this thing I couldn't find this thread even though I have been "following" it since the beginning. Of course the original thread from 1865 that is linked from the vintagemicpcb site doesn't help with this specific build despite being easy to find.
I will desolder and try to get the boards apart without destroying them.
If counterfeit and **** FETs are this rampant, what do you guys do? Buy a metric ton and spend an evening testing each one? My bad for assuming Mouser is above reproach and not testing any of the transistors before installing them.
Of course I practice safe soldering and use a heat-sink condom on all semiconductors, styros, etc.

 

[neowalla]

I was able to separate the boards by unsoldering the JP3, 4 connections from the amplifier board without too much drama or trauma. Lesson learned there.
Solder joints all look good under magnification. No shorts, cold joints or the like.
After powering up with P48, it produces audio for a couple seconds. Then it is as if the invisible hand of the engineer slowly pulls the fader down, and all becomes silent. Does anyone know what could be a likely suspect?

 

[Quantum J Audio]

My bad for assuming Mouser is above reproach and not testing any of the transistors before installing them.
Of course I practice safe soldering and use a heat-sink condom on all semiconductors, styros, etc.

I always socket my transitors and fets. Makes it easy to pull them out and test if you need too.

 

[neowalla]

I always socket my transitors and fets. Makes it easy to pull them out and test if you need too.

That's a great idea! I've given up on this mic for the time being. Attempting to trace the circuit and measure voltages with the boards piled on top of each other is just stupid frustrating. I will never build another round PCB mic. Way too much of a PIA for my level of patience.

 

[EarthTone]

That's a great idea! I've given up on this mic for the time being. Attempting to trace the circuit and measure voltages with the boards piled on top of each other is just stupid frustrating. I will never build another round PCB mic. Way too much of a PIA for my level of patience.

I am really sorry to hear of your frustrations. I built two of these and they are some of my best mics. I would have to go back and read your posts again, but when I skimmed them before it seemed like maybe you’d used some old or questionable parts. I would encourage anyone building this mic to stick with the original BOM when selecting parts. Sometimes parts are no longer available or out of stock, but if you know how to match values and make sure they’ll fit (Mouser lists product dimensions), you can find brand new suitable alternative parts. I’ve yet to buy a bad or counterfeit transistor from Mouser or Digikey. My point is not meant to be condescending at all, please don’t take it that way. I would encourage you to remove any questionable parts and reinstall with new known good modern parts.

Some of the parts in this build have been unavailable for years. For example if memory serves there’s a 220Mohm resistor which you can’t get anymore. In cases like this you can run a 20Mohm and a 200Mohm resistor in series to achieve the same resistance required.

I wish you success in finding the faulty part. To me this sounds like a capacitor problem if you are getting sound and then it dies off. Maybe start with pulling all the caps and reinstalling new ones? Just an idea.

Resistors can be tested in circuit. That’ll make it easier for you to test those.

On builds like these I test every part possible on my multimeter before installing. Every single resistor, cap, etc. even if it comes directly out of a brand new labeled bag with the part’s electronic value written on it, I don’t trust that. Saves you a lot of headaches later. Sometimes you find a part is just wildly off of the value of what it’s marked and you can select a part with a closer value to the tolerance range from the same batch of parts. Sometimes I order extra parts just because of this. The bonus is then you have extras of those parts around later for the next time a similar problem pops up.

Best,
Matt

 

[TLRT]

I was able to separate the boards by unsoldering the JP3, 4 connections from the amplifier board without too much drama or trauma. Lesson learned there.
Solder joints all look good under magnification. No shorts, cold joints or the like.
After powering up with P48, it produces audio for a couple seconds. Then it is as if the invisible hand of the engineer slowly pulls the fader down, and all becomes silent. Does anyone know what could be a likely suspect?

Check the big top copper spacers. they can reach and damage the pcb traces and ground the signal path.