Transformer

[GregS]

I have an old HP 6268B which has a shorted transformer. Tried replacing it with
another. The new transformer is from the shelf. The new transformer does not
seem to like the traic switching. Are there different cored transformers
for switching?

These are big transformers!

greg

 

[John Popelish]

I have an old HP 6268B which has a shorted transformer. Tried replacing it with
another. The new transformer is from the shelf. The new transformer does not
seem to like the traic switching. Are there different cored transformers
for switching?

These are big transformers!

greg

Perhaps the TRIAC switching is broken (not symmetrical on the positive
an negative half cycles), producing a net DC through the transformer.
This may be what burned up the original transformer.

 

[Genome]

I have an old HP 6268B which has a shorted transformer. Tried replacing it
with
another. The new transformer is from the shelf. The new transformer does
not
seem to like the traic switching. Are there different cored transformers
for switching?

These are big transformers!

greg

Yes, they are also Robots in Disguise.

If you do a Google search you might find out what Optimus Prime's e-mail
address is and ask him about it. Just don't mention anything about the
situation between his son and Renault.

DNA

 

[Homer J Simpson]

I have an old HP 6268B which has a shorted transformer. Tried replacing it
with
another. The new transformer is from the shelf. The new transformer does
not
seem to like the traic switching. Are there different cored transformers
for switching?

Is it on/off switching or phase controlled? Has the triac controller failed?

 

[GregS]

Perhaps the TRIAC switching is broken (not symmetrical on the positive
an negative half cycles), producing a net DC through the transformer.
This may be what burned up the original transformer.

Something like this could be likely. I was just thinking, The orginal triac
was found shorted. The transformer also has a short, drawing over 5 amps
right now. I replaced the triac, but not with an orginal part. The new transformer
is drawing over 10 amps with the triac. When I short the triac it is
normal, or full voltage out of the transformer. I am gong to configure the supply
without the triac and use the supply as a reduced voltage supply, up to 15 volts.
I have the taps where I can do this. The transformer from the shelf has
been on the shelf for at least 25 years. Signal Transformer 68 volts @ 12 amps.
These Signal transformers are rated for a 10% drop !!.


greg

 

[GregS]

Is it on/off switching or phase controlled? Has the triac controller failed?

I was orginally looking a long time at the triac controller. Stuff is hard to measure,
but it could very well be faulty. I did not go back and check the waveforms
after I replaced the triac.

greg

 

[Homer J Simpson]

I was orginally looking a long time at the triac controller. Stuff is hard
to measure,
but it could very well be faulty. I did not go back and check the
waveforms
after I replaced the triac.

Can you bypass the controller and run it off AC? Works OK?

There is a slight possibility that the transformer was designed for some DC
through it - it might have an air gap, although I'd be amazed.

 

[GregS]

Can you bypass the controller and run it off AC? Works OK?

There is a slight possibility that the transformer was designed for some DC
through it - it might have an air gap, although I'd be amazed.

Bypassing the controller is simply a matter of watching not to over
drive the output transistors. Its not going to be able to put out 20 volts
at 30 amps unless the rail is not to excessive to overheat the sinks.
Its really got room to speare though.

greg

 

[Homer J Simpson]

Bypassing the controller is simply a matter of watching not to over
drive the output transistors. Its not going to be able to put out 20 volts
at 30 amps unless the rail is not to excessive to overheat the sinks.
Its really got room to speare though.

OK. It has a triac in the primary or secondary? If in the secondary that's
not the problem. Without a circuit diagram, the triac I assume is acting as
a lossless resistor - should not affect the transformer. Either it is bad or
under rated IMO.