Halicrafters S-120 Question - Videokarma.org TV - Video

NYListens · #1 11-10-2008, 07:33 PM

I am in the process of recapping one of these boat anchors. I have replaced all of the electrolytics and almost all of the other caps except the micas and ceramics and it is still has an extreme ac sound to it. Could it be the rectifier? Any suggestions on replacing the rectifier? Can I use two diodes in series, and if so, which type of diode should I use? I also need to replace the Globar resistor and have no idea what I should use.

electronjohn · #2 11-10-2008, 07:41 PM

You might try inserting the AC plug in the opposite direction... flipping the plug may eliminate the hum.

markdi · #3 11-10-2008, 09:42 PM

I bought a nice looking s120 at the thrift store for 3 dollars
yesterday - mine hums a little too

NYListens · #4 11-10-2008, 10:00 PM

Have you recapped it yet?

markdi · #5 11-10-2008, 10:59 PM

no I have not recapped it.

What is a Globar resistor ?

NYListens · #6 11-10-2008, 11:20 PM

Quote:

Originally Posted by markdi

no I have not recapped it.

What is a Globar resistor ?

I believe they are non-inductive ceramic (not wire through ceramic.)

stahlhart · #7 11-22-2008, 10:50 PM

Quote:

Originally Posted by NYListens

I am in the process of recapping one of these boat anchors. I have replaced all of the electrolytics and almost all of the other caps except the micas and ceramics and it is still has an extreme ac sound to it. Could it be the rectifier? Any suggestions on replacing the rectifier? Can I use two diodes in series, and if so, which type of diode should I use? I also need to replace the Globar resistor and have no idea what I should use.

The specification on the globar is 680-100 ohm. I have doubts that you're going to have any luck finding a replacement these days.

Why do you feel that it needs replacing? Looks to me that it provides some sort of current regulation for the filament / panal lamp string.

The rectifier is selenium; you could probably substitute a silicon one if you had to, perhaps 1N4002 would work. Two in series isn't going to accomplish anything. It's a low-cost half-wave design, and without a power transformer there's not much you can do to improve on it.

Have you tried another 12AV6? Do you have hum in the audio with the volume all the way down?