K&K Audio / Lundahl Transformers

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K&K Audio / Lundahl Transformers

Bellari RP220 mod - LL1530

68.32.94.88

Dusting off my Bellari RP220 and putting in a LL 1530 input tranny to bring out some life from the tube preamp.

Does anyone know where color codes leads connect to the 1530?

Thanks!!

Follow Ups:

RE: Bellari RP220 mod - LL1530 - KevinC 17:57:50 09/22/09 (2)
Gotta schematic?

Kevin Carter
K&K Audio
www.kandkaudio.com
- RE: Bellari RP220 mod - LL1530 - electricgoose 07:23:40 09/23/09 (1)
  I couldn't find a schematic for the RP220. It was a Black Lion Audio modification that was suggested to replace the stock input tranny with a LL1530, but no instructions on hookup. I took my best guess and hooked up the tranny, but I got a low output. I tried to reverse the wiring but same problem.
  
  The four wires going to the PCB for the input tranny are - One to ground. One to (+) XLR in. One to (+) XLR in though a resistor. One to input pad switch.
  
  If you have any hints on where to start, let me know. Otherwise I will keep trying to figure out the schematic by looking at the pcb.
  
  Thanks for your help!
  - RE: Bellari RP220 mod - LL1530 - KevinC 05:36:07 09/24/09 (0)
    My first guess would be that the transformer should be wired as 1:7, which is shown in the LL1530 data sheet at the bottom right. The input side (left side in the data sheet diagram) "+" lead should be connected to XLR pin 2 and the other lead to XLR pin 3. The output side "+" lead should be connected to the input pad on the PC board and the other lead to the PC board ground. You can determine which is ground and which is input using an ohmmeter. Connect one ohmmeter lead to an obvious PC board ground point and then test the two input pads. One should read almost no resistance (that would be ground) and the other should be much higher ( that would be the input).
    
    Kevin Carter
    K&K Audio
    www.kandkaudio.com
    - Data Sheet for LL1530 (Open in New Window)

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