magicsam

Wow, the Sunfire sure is a beast! I replaced 13 of the 470uF filters on both boards and two 47uF 200V in the regulating section. It works well but has a slight hum that increases slightly with more gain. I still want to know if any more tips on getting this cured?

Hi again RobertR! No, I was not insulted, better safe than sorry. If you could send me the schematic you do have it would be a great help to understand the topology of these designs. I have been a factory trained Crown Audio technician, in fact one of the instructors at Crown school was in my high school electronics classes. I sat in the back and resisted the urges to heckle him! My parts order was on my doorstep this last weekend, repair is soon. My patient is definitely older than MkII and a roadmap is something I could appreciate. I am fairly good at reverse engineering, the MkII roadmap would easily help understand where the highest stress components are. Thanks again for your input and I hope to hear from you soon!

You are all very friendly, thanks! RobertR, I have been fixing electronics a long time, a 60 watt light bulb with alligator clips has been my cap discharge tool for years. And yes, I think this one is an original TS. I have a bunch of the 470uF/25V due any day, along with two 2700uF/200V and two 47uF/200V that are in the power supply. Sort of the shotgun repair technique! Those first caps are under a lot of stress, especially since they are run half wave, lots of ripple current! I have also considered adding an inrush current limiter to protect the bridge rectifier and the caps. I will keep you all updated as I go, thanks for your support.

Thanks guys! I believe this is an oldie, the serial number is 9611302256, which the last four digits are inside the panel as 2256 in marker pen. My friend said they are prone to capacitor failure, both the two main filters and several power supply caps. I have ordered some new from Mouser. I did already replace three IRF630 FETS and their gate resistors (9.1 ohm/ 1/6w) and also did find a cold solder joint on the back of the AC fuse holder. The speaker now does function somewhat, but with a background hum and occasional popping noises. Any hints you can give would be appreciated.

I am a semi-retired electronic technician who is also a performing musician and sound engineer. I have been repairing electronics all my life and have worked on a few of Bob Carvers amplifiers. I was hoping someone had a service manual for a Sunfire True Subwoofer. A tech friend used to service these but is no longer working in audio.