SjorsDahmen
Member
I can measure AC in and out of the input transformer. After the the resistors and diodes, on test point F and H there is no AC but there is 650mV DC. On the input pins of the interstage transformer there is 3.6V DC. there is nothing on the output pins of interstage transformer. Are these measurements normal/correct? These measurements are taken with the setting written in the 1st step of calibration with 1 khz sine wave connected to input.
Hi Ateshk,
I’m also in the middle of a DR609 build, and I’ve experienced the same problems you did. With my unit it had something to do with a few transistors on the opamp cards that had problems. Be careful to keep the trimpot on the opamp cards all the way down, until the calibration process, or it will run really hot and damage components. I do get signal in and out of the unit now. I couldn’t measure anything at the interstage transformer, might be because the signal is very low there. I started calibrating my unit, and the limiter section is actually working perfectly if I leave the wiring for the compression section unplugged. As soon as I plug in the control B wiring, the reduction meter jumps to -20 db and stays there no matter what I do with the controls. Did you manage to get yours working?
Hi Ateshk,
I’m also in the middle of a DR609 build, and I’ve experienced the same problems you did. With my unit it had something to do with a few transistors on the opamp cards that had problems. Be careful to keep the trimpot on the opamp cards all the way down, until the calibration process, or it will run really hot and damage components. I do get signal in and out of the unit now. I couldn’t measure anything at the interstage transformer, might be because the signal is very low there. I started calibrating my unit, and the limiter section is actually working perfectly if I leave the wiring for the compression section unplugged. As soon as I plug in the control B wiring, the reduction meter jumps to -20 db and stays there no matter what I do with the controls. Did you manage to get yours working?