is this right?

[papajeaux]

i'm trying to understand power transformers. this is from the hammond 270bx.

"The 270 Series power transformers use the convenient 4 hole above chassis "X" type bell end mounts. Each unit features a 115 VAC, 60 Hz primary and two secondary filament windings, one 5.0V for tube rectifiers, plus a 6.3V for heater filaments. Leads are a minimum of 6" in length. Class A insulation (105ºC). These transformers are conservatively rated and CSA certified. VA: 95, Secondary RMS: 300-0-300, DC mA: 100, Fil. #1 Rectifier: 5.0V/2A, Fil. #2 Heater: 6.3V/3.0A."

115VAC, 60Hz primary = what it needs from the wall (mains) to go.
300-0-300 secondary = one tap will be +300VDC, another -300VDC, and the center is neutral.  600VDC across the entire secondary.
100mADC is secondary current flow = 30W of power to the speaker?
                    [300VDC*.1ADC=30W]
95VA = apparent power the amp is making?

am i understanding that right? CT is center-tapped meaning the leads come off the secondary winding wire in the middle of the wire?  like if you straightened it out.  so this transformer is a 3 phased, CT power transformer?

it has taken me 3 days to pull all of these "ideas" together b/c i can't find anywhere that explains this all in layman's terms (ie. the 270bx needs input of 115V @60Hz to make 300V out which will be a replacement for a 30W amp).  or maybe: X model transformer goes into  Zwatt amp, and here is why.

however, i have learned a lot of other things:  did you know that money does not grow on trees?  i never knew that.

pj

[iTzALLgoOD]

115VAC, 60Hz primary = what it needs from the wall (mains) to go.

correct

300-0-300 secondary = one tap will be +300VDC, another -300VDC, and the center is neutral.  600VDC across the entire secondary.

The voltage is still AC at this point.  If you measure across the 2 legs with a meter set to AC you'll measure 300V.

I used a 270 in a tube amp that I built.  Most SS amps use transformers with lower voltage and higher amperage.

Do you need to replace a transformer or are you just curious about the ratings?

[papajeaux]

thanks allgood.  the rectifier turns it into dc.  and, not sure if i lost pt or not.  no pwr when i used the bulb limiter.  i'd previously posted that i'd checked everything but the caps.  but, now i'm in doubt as to my checking proceedures (read: sequence).  so, i'm back to square one.  but, won't make that mistake again.  also getting a lot of practice w/the iron.

so, a 48v ct, 3A pt would work, wouldn't it?  that would be 144VA (RMS).  wouldn't that come out to @ 50-60W to the speaker?  would that do it?  or too low?  why?

pj

[iTzALLgoOD]

It all depends on the circuits' requirements.  You'll need a schematic or a Crate part number to find the right transformer.  You might be able to see if there is a number on the transformer and find out it's ratings.

[papajeaux]

yeah, i'm waiting to hear back from crate w/part# and schematic.  the ONLY markings on the transformer are two stickers.  one has an SLME #, the other says, "High Pot Tested".  i can't find any references to any crate part#'s.

[teemuk]

Check your email papajeaux...