toriodal load temp

Status
Not open for further replies.
Jump to Latest
intensate

intensate

Member
Joined 2012
#1
Hello all.

I am using a arcam alpha 3 toroidal in a jlh class a amp and its
temp from top washer plate is 60c and from side windings its 55c.
Its only ticking over at these temps,neighbors in so cant turn it up!

Is this a normal temp?

thanks
 
#2
too hot. Can you imagine the internal temperature?

Are you able to measure the primary current after you have disconnected the secondary loads?

Or power up the transformer alone through a Mains Bulb Tester using a 30W to 40W incandescent bulb.
 
#5
If you have a diode bridge you can measure AC current with a cheap multimeter.

It needn't be high voltage because drop across it is small, it's used in series with mains.

Measurement is not exact, but it will be in the ballpark, close enough to decide between "normal/worry"

But be careful, diodes and meter will be connected to dangerous mains voltage.
 
#7
Here it is.

Remember you'll be working with live mains.

Works very well with old needle type meters, because needle integrates/averages readings, a digital multimeter may flicker something depending on its internal averaging, nothing too bad.

An externally hosted image should be here but it was not working when we last tested it.


Set multimeter to 10A scale (the 200mA one will be too small, unless you are measuring something like a cellphone charger and being fused, will open in a jiffy)

Good luck.
 
#12
I use a 4way screwed insulated terminal strip.
terminal1 is Live in out
terminal2 is Neutral in and 1r0 out
terminal3 is Neutral out and 1r0 in
terminal4 is Earth in out.

I then wrap the whole thing so that ALL the cables ends and terminals and the strip are insulated with at least two layers of RED insulating tape.
I puncture the tape to the two terminal heads that have the 1r0 attached. I can now insert the probes of a mains rated voltmeter through the puncture holes.

I use the Vac on the DMM to measure the voltage drop across the 1r0 to estimate the current passing back from the neutral wire.

1mVac = 1mAac
199mVac = 199mAac
3.00Vac = 3.00Aac this will blow the 600mW 1r0 resistor, (0.6Aac through 1r0 dissipates ~400mW. This will start to melt the insulating tape !)

BUT !!!!
you are measuring LIVE voltages.
Be very careful !
 
Last edited:
#15
Use a Mains Bulb Tester for EVERY mains powered project EVERY time you modify it.

Shorting the transformer due to wiring errors can destroy transformers.
Seems like incompetence destroyed your transformer.

Use that tester EVERY time.
 
#18
speedskater.

I replaced its mains lead as it had an old cotton type,and metered its earth so I know the earth is working ok .
I will check to see if your right later.
thanks.
The toroidal was shot, but I learned from it and took another e i type and modded it today.
its 2 19vac sec were tied in a tap and I separated them so I have 2 isolated 19vac sec.
they are running my amp great and they don't get warm!!!
thanks everyone I have learned a lot of useful info.
 
Status
Not open for further replies.
Top Bottom