Re: Selenium rectifier question

On Fri, 11 Apr 2008 14:19:39 -0700 (PDT), EricM <ew_morr@xxxxxxxxxxx>
wrote:

I have replaced two old Federal/ITT selenium rectifiers in an
amplifier power supply with new silicon diodes; the original part
numbers are 103H4AX1 and 104B1AX1. I can't find any reference to
either part on the web - anywhere - ITT can't even provide
information. Since one of the legs of the circuit supplies the plate
voltage (600V) I used 600V 10A diodes (NTE5815HC) to be safe. Problem
is, there is a time-delay relay that closes to engage the 600V
circuit, and without it attached to the amp; all tube supplies,
biasing voltage, etc. are normal. If hooked up, once the relay closes
- the main power fuse blows. I'm guessing I need a dropping resistor,
but it would be nice to have the original data on the selenium parts
to be able to figure out the value. The 600V and the -38V biasing
voltage are derived from the same part of the power transformer. The
-38 side works, but the 600V side reads upwards of 927 volts without a
load. Using a Variac, the plate voltages were above 600V at about 70
percent. Is there a way to find the original specs on these selenium
parts? Any leads would be greatly appreciated!


You obviously need much more than 600 volt diodes. It is the PIV
which is important. What is the open circuit transformer output AC
voltage, and what is the circuit configuration used. ? You can
thencalculate the needed rating of the diodes and then add a good
safety factor.

Peter
.

Relevant Pages

  • Re: Selenium rectifier question
    ... - the main power fuse blows. ... but it would be nice to have the original data on the selenium parts ... voltage are derived from the same part of the power transformer. ... If the DC voltage is 600 volts you need higher voltage diodes. ...
    (sci.electronics.repair)
  • Re: Updated info on the problem
    ... The following readings are for the problem amp. ... meter to measure the diodes. ... power capacitors, which should be 500v is actually, 400v. ... There may be several reasons for the lower voltage. ...
    (rec.audio.tubes)
  • Re: That Lowes flashlight, again
    ... I think where you're confused is that you're looking at the AC input power and the full wave rectified power, ... Indeed, with perfect diodes, you'd have 100% efficiency, but you won't have DC yet! ... LEDs are constant voltage devices. ... The only reason to stack 2 or more LEDs in a generator driven application is to improve the efficiency slightly by matching the generator load more closely to its designed load and making the real rectification power a smaller fraction of the load power. ...
    (rec.bicycles.tech)
  • Re: That Lowes flashlight, again
    ... misquote) a reference on rectification. ... power and the full wave rectified power, ... with perfect diodes, you'd have 100% efficiency, but you won't have DC ... You are mixing up voltage and power. ...
    (rec.bicycles.tech)
  • Re: 11V to 15V AC/DC switching power supply?
    ... power) switching power supply? ... circuit possibilities? ... front of, and its meant to be adjustable in my voltage output range, ... which are reference circuits for each of their switching ...
    (sci.electronics.design)