Hi Everyone,
Here's a few pics of my most recent DIY.... 8 channels of NewYorkDave one-bottle mic pre in a 2 rack space chassis.
and here's the power supply:
I just finished tracking a band and I love how this baby sounds. Just for variety I laid out the PC board with a dual footprint for cinemag and also lundahl input transformers. You can see in the top view pic that the first four channels have the cinemag and the others are lundahl.
Now I find that I've got some troubleshooting to do. I was in such a hurry to get this ready for tracking the band, I literally made the last solder joint minutes before the session started and so I didn't have time to check voltages or anything. It was clean, passing signal and no hum or noise....that was good enough for me so I bolted it in the rack and used it for the session which took about 1 week.
Now 5 channels have become very distorted! Upon checking voltages i find that they are all way too high. The 3 channels that are still clean read too high as well but not as high as the 5 bad ones. B+ at the power supply is 296 volts and the voltages at the tubes are as follows:
Tubes are NOS GE JAN dated 1977. All resistors are PRP metal films except for R9 which is a Kiwame. R12 is 22k. I lowered the value of C5 to 10uf. I also bypassed C5 with a 0.01 uf cap. All other component values are as per the original schematic except for C4 (as was noted) I used a 4.7 uf film cap. R10 was eliminated....transformer out only. Output transformers are Edcor WSM600/15k.
I hope someone can help me out here, or point me in the direction of what I should be looking for ???
Thanks in advance and also a big thanks to Dave!
Freddy
Here's a few pics of my most recent DIY.... 8 channels of NewYorkDave one-bottle mic pre in a 2 rack space chassis.
and here's the power supply:
I just finished tracking a band and I love how this baby sounds. Just for variety I laid out the PC board with a dual footprint for cinemag and also lundahl input transformers. You can see in the top view pic that the first four channels have the cinemag and the others are lundahl.
Now I find that I've got some troubleshooting to do. I was in such a hurry to get this ready for tracking the band, I literally made the last solder joint minutes before the session started and so I didn't have time to check voltages or anything. It was clean, passing signal and no hum or noise....that was good enough for me so I bolted it in the rack and used it for the session which took about 1 week.
Now 5 channels have become very distorted! Upon checking voltages i find that they are all way too high. The 3 channels that are still clean read too high as well but not as high as the 5 bad ones. B+ at the power supply is 296 volts and the voltages at the tubes are as follows:
Tubes are NOS GE JAN dated 1977. All resistors are PRP metal films except for R9 which is a Kiwame. R12 is 22k. I lowered the value of C5 to 10uf. I also bypassed C5 with a 0.01 uf cap. All other component values are as per the original schematic except for C4 (as was noted) I used a 4.7 uf film cap. R10 was eliminated....transformer out only. Output transformers are Edcor WSM600/15k.
I hope someone can help me out here, or point me in the direction of what I should be looking for ???
Thanks in advance and also a big thanks to Dave!
Freddy