Help: T-bone Sct2000/Nady TCM1050 with new K47 capsule, 6072a and BV8 style tfx

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manulaudic

Well-known member
Joined
Nov 7, 2011
Messages
363
Location
Finland
Hi guys,

I am starting the mod of my microphone after researching a lot around i got some parts from AAmicrophones.
Dave has been very helpful providing the parts and now i am facing some issues.

I am starting with the circuit, i removed C6, C7, C9 and C10 and i have swapped C8 for a 2.2ufd

I have taken the Transformer out and i will be putting the new one in... it's quite difficult to get the cables around since the leads from the BV8 are very short... i have to clean up a bit.

Now i am looking at the power supply.

Dave sent me a Zener diode which is 1N4754a which should be 39volts.

THough the one on my PSU, D5 and D6 are respectively 1N4782A (82volts) and 1N4780A(68volts).

I don't know which value i should be ending with and which Zener diode to change... Maybe both? or should i swap D6 with the 1N4754A and get a total of 121 Volts?
This voltage should be bringing down a bit the harshness from the capsule i heard.

Finally i will be trying the mic with the stock capsule before installing the K47 one...

I would greatly appreciate if you guys could help with that Zener diode and any other tip...

Here are some pics :
 

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120V is a good spot for your B+ to be. I used one 62V and a 56V when I last modded an alctron PSU.

That body, capsule and transformer is probably a good candidate for a G7. However, you will have to modify your own PCB by removing the space for a PCB mount transformer as Jakob's layout is too long and won't fit. It's fairly simple to do though.
 
Thanks Enchilada,

I will stick with 121 volts then replacing that Zener.
The circuit is exactly the same at the Apex 460... though the body is more of a U47 like.

I am not gonna go for a G7 though, i've heard lots of things about it and i'd like to build that separately. Maybe something in between Royer mod and G7.

now i will be upgrading the circuit exactly the way Dave Thomas adviced me and we'll see.
I'll keep on posting pictures and by the end of the week some sounds samples...

Manu
 
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