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previous: Ian I built a little Fender 50w type am... -- 7/3/2000 9:08 PM View Thread

Re: Fender Homebrew with JCM900PT question

7/3/2000 9:37 PM
Ray Ivers
Re: Fender Homebrew with JCM900PT question
I don't think the unused LV winding would have any effect on noise, but... I have found these JCM900 transformers to have a noise problem on the 6.3 volt heater winding - as soon as the standby switch is turned 'on' and current flows thru the high voltage secondary, the 6.3 volt winding seems to saturate and the 60 Hz waveform distorts, putting all sorts of hum and buzz onto the tube heaters. I had to install an auxiliary 6.3 volt transformer in my own 6100 amp to get it quiet, after replacing the power transformer with no effect. The newer JCM2000 transformers look identical but have different Dagnall part numbers, and seem much quieter.  
Ray Ivers

Ian Thank you for your reply Ray! -- 7/4/2000 11:07 AM