Old Transformer Replacement

S

sck0006

Guest
We need to find a replacement transformer for an old unit. The
original has a dead short between primary and secondary. As best as I
can tell, the transformer is marked Vernon Co., V_6021, Pri:135VAC Sec:
25VAC. It feeds into a full wave rectifier into a DC motor, no
capacitors. The motor draws 24V at 12.2A, per the mfg dataplate. Any
ideas for a replacement transformer? Line frequency is 400Hz, but
60Hz transformer will be just fine.

Thanks,
Steve
 
sck0006 wrote:
We need to find a replacement transformer for an old unit. The
original has a dead short between primary and secondary. As best as I
can tell, the transformer is marked Vernon Co., V_6021, Pri:135VAC Sec:
25VAC. It feeds into a full wave rectifier into a DC motor, no
capacitors. The motor draws 24V at 12.2A, per the mfg dataplate. Any
ideas for a replacement transformer? Line frequency is 400Hz, but
60Hz transformer will be just fine.

Thanks,
Steve
Click to expand...
Two of part # 7846 TR from MPJA in parallel.
It's a 24V 10A transformer, at $17.95 each.

Ed
 
sck0006 wrote:
We need to find a replacement transformer for an old unit. The
original has a dead short between primary and secondary. As best as I
can tell, the transformer is marked Vernon Co., V_6021, Pri:135VAC Sec:
25VAC. It feeds into a full wave rectifier into a DC motor, no
capacitors. The motor draws 24V at 12.2A, per the mfg dataplate. Any
ideas for a replacement transformer? Line frequency is 400Hz, but
60Hz transformer will be just fine.

Thanks,
Steve
Click to expand...
Grab the xfmr out of a an old junk microwave, 500w or better should
serve. Cut-out/remove high voltage winding and knock out the "current
shunts (core material "shims" wedged in the windings windows.)

Rewind with wire capable of handling the current you wish, with the
proper number of turns to deliver the voltage you desire (this can
easily be determined by winding any number of test turns (10 or more to
get some accuracy), measure voltage and divide by number of turns to
give you a volts/per-turn ratio.

Cost (if xfmr is gotten from a dump) $0.00 USD! :)

Regards,
JS
 
On Wed, 23 Jan 2008 14:57:32 -0800, John Smith
<assemblywizard@gmail.com> wrote:

sck0006 wrote:
We need to find a replacement transformer for an old unit. The
original has a dead short between primary and secondary. As best as I
can tell, the transformer is marked Vernon Co., V_6021, Pri:135VAC Sec:
25VAC. It feeds into a full wave rectifier into a DC motor, no
capacitors. The motor draws 24V at 12.2A, per the mfg dataplate. Any
ideas for a replacement transformer? Line frequency is 400Hz, but
60Hz transformer will be just fine.

Thanks,
Steve

Grab the xfmr out of a an old junk microwave, 500w or better should
serve. Cut-out/remove high voltage winding and knock out the "current
shunts (core material "shims" wedged in the windings windows.)

Rewind with wire capable of handling the current you wish, with the
proper number of turns to deliver the voltage you desire (this can
easily be determined by winding any number of test turns (10 or more to
get some accuracy), measure voltage and divide by number of turns to
give you a volts/per-turn ratio.

Cost (if xfmr is gotten from a dump) $0.00 USD! :)

Regards,
JS
Click to expand...
Thanks guys, I appreciate the help.

Steve
 
Steve wrote:

...
Thanks guys, I appreciate the help.

Steve
Click to expand...
No problem. However, if I might inquire, did you go the hard route of
building your own, or find a place to buy one?

Warm regards,
JS
 
On Thu, 24 Jan 2008 11:55:10 -0800, John Smith
<assemblywizard@gmail.com> wrote:

Steve wrote:

...
Thanks guys, I appreciate the help.

Steve

No problem. However, if I might inquire, did you go the hard route of
building your own, or find a place to buy one?

Warm regards,
JS
Click to expand...
We will probably buy one. This is meant for relatively long periods
of use, and in my experience rewound mot's run hot and usually need
fan cooling. We will probably just order two of the xfmr's the
previous poster recommended, that is, if the cust decides it's worth
it to them.

Thanks again,
Steve
 
Steve wrote:

...
We will probably buy one. This is meant for relatively long periods
of use, and in my experience rewound mot's run hot and usually need
fan cooling. We will probably just order two of the xfmr's the
previous poster recommended, that is, if the cust decides it's worth
it to them.

Thanks again,
Steve
Click to expand...
I understand.

Was just hoping good old "American Ingenuity" had come into play. :)

Regards,
JS
 
On Jan 24, 2:26 pm, John Smith <assemblywiz...@gmail.com> wrote:
Steve wrote:
...
We will probably buy one. This is meant for relatively long periods
of use, and in my experience rewound mot's run hot and usually need
fan cooling. We will probably just order two of the xfmr's the
previous poster recommended, that is, if the cust decides it's worth
it to them.

Thanks again,
Steve

I understand.

Was just hoping good old "American Ingenuity" had come into play. :)

Regards,
JS
Click to expand...
I've actually rewound microwave transformers before, they're quite
handy. I use one for a high voltage power supply using the schematic
Sam has at http://www.repairfaq.org/sam/hvinvert.htm
It works beautifully, and I have the top of the core of the
transformer sticking out of the case for cooling. I would definitely
consider using a mot if it weren't customer equipment, I'm not sure
how long they use it at a time, and I don't want it to melt down on
them for whatever reason.

Thanks,
Steve
 
"John Smith" <assemblywizard@gmail.com> wrote in message
news:fnas8q$gv5$6@news.albasani.net...
Steve wrote:

...
We will probably buy one. This is meant for relatively long periods
of use, and in my experience rewound mot's run hot and usually need
fan cooling. We will probably just order two of the xfmr's the
previous poster recommended, that is, if the cust decides it's worth
it to them.

Thanks again,
Steve

I understand.

Was just hoping good old "American Ingenuity" had come into play. :)

Regards,
JS
Click to expand...
Bad idea John,

1) Microwave transformers are sealed with Epoxy making impossible to
unwind.

2) Even if you can unwind, you are still facing with dangerous chance,
there are many turns, to unwind without know the actual number of turns
would destroy the motor (through wrong voltage/power).

Never do that, and Never recommend to any one.

Regards,

Jack.
 
sck0006 wrote:
We need to find a replacement transformer for an old unit. The
original has a dead short between primary and secondary. As best as I
can tell, the transformer is marked Vernon Co., V_6021, Pri:135VAC Sec:
25VAC. It feeds into a full wave rectifier into a DC motor, no
capacitors. The motor draws 24V at 12.2A, per the mfg dataplate. Any
ideas for a replacement transformer? Line frequency is 400Hz, but
60Hz transformer will be just fine.

Thanks,
Steve
Click to expand...
http://www.hammondmfg.com/ make a great variety of transformers for any
applications. Will wind special cases. Have a great museum of old
radios...been in business since the 1920s or so...

John :-#)#

--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
 
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