Folks, I have a transformer I scrapped from an old console radio. Unfortunately, I wasn't able to get a model number for the radio and all I have is the transformer. I can't seem to find the details online so im hoping someone can help me identify or give me info on how to test it.
Images attached below. It looks like a very well made transformer so I would like to identify and store it for a later project maybe. I've been taking apart a lot of old audio equipment from console radios and saving era specific hardware for projects. I love the older wire that's wrapped with a weaved fabric.
Any help would be appreciate, if there is already a thread that covers this, please point me to it.
Images attached below. It looks like a very well made transformer so I would like to identify and store it for a later project maybe. I've been taking apart a lot of old audio equipment from console radios and saving era specific hardware for projects. I love the older wire that's wrapped with a weaved fabric.
Any help would be appreciate, if there is already a thread that covers this, please point me to it.
Attachments
USA radio? Common code would have the two reds as high voltage and the red/yellow as their center tap. The green/green-yellow pair would be 6v for heaters. Leaving the other two for primary.
I would use my variac and current meter to test it. Or run 6v from another source into teh green pair and see if you get a few hundred across the reds and 120 on the gray.
I would use my variac and current meter to test it. Or run 6v from another source into teh green pair and see if you get a few hundred across the reds and 120 on the gray.
My first step would be to use an ohmmeter to see which wires are connected to different windings.
Then proceed as Enzo suggests. You can use a 'wall wart' power supply which has AC output (not the more common DC ones) as your AC source if you don't have a Variac.
Then a bit of work with a voltmeter and a calculator will give you the voltage information.
That is a good point, I was assuming the color code was standard, an ohm meter will verify if the wires are paired as I assumed.
Thanks guys, I really appreciate the info. This is above my head technically since I don't regularly practice this but I need to learn it. Off to youtube to learn I suppose. I was hoping that there was a repository somewhere of old tech sheets that would relate to those numbers stamped on the transformer but ill make due.
First:
You must identify the different windings. and how many taps are on each winding.
Second:
Measure the resistance of each winding and from tap to tap if there are intermediate tappings.
Third:
Build and use a Mains Bulb Tester for first power ON. This limits the damage if you have made a mistake in guessing which is the Primary winding and if any winding has an internal short.
Be safe: I suggest you use some form of insulated terminal block so that no wire end is exposed to an inadvertant touch by a finger or tool.
You must identify the different windings. and how many taps are on each winding.
Second:
Measure the resistance of each winding and from tap to tap if there are intermediate tappings.
Third:
Build and use a Mains Bulb Tester for first power ON. This limits the damage if you have made a mistake in guessing which is the Primary winding and if any winding has an internal short.
Be safe: I suggest you use some form of insulated terminal block so that no wire end is exposed to an inadvertant touch by a finger or tool.
I will keep all this in mind. I am familiar with the light bulb limiter, I've used one in the past when rebuilding tube amps. I'm just not that familiar with transformers. I get the concept, just not how to reverse engineer them.
It could be similar to the one shown in this power supply. It will give you an idea about the separate windings that you need to identify with a multimeter to start with DIY 6T9 Tube (Valve) Single-Ended Amplifier Kit
I have the similar problem - I scrapped a transformer from an old amplifier. It is some kind of output transformer, I know that because it was connected to output jacks. However, when I measure the voltage ratio of primary and secondary I get this: P:S=4,18:1. What kind of output transformer could it be? Can I use it as an output transformer for a tube amp?
Could it be an output transformer for distributed speaker systems (like constant voltage 70 volt set ups) ?
Just as a note, I haven't had a chance to figure out what type of transformer mine is or the specs. The procedure is above my head. Although I have some electrical experience and am in the process of building the "Engineers Amp" tube amp, I am following instructions and learning as I go.
If anyone has the patience to link me to some educational youtube videos that can help me with this, I would love to learn how to sort this out. I want to tag the transformer and store it for later use if possible.
If anyone has the patience to link me to some educational youtube videos that can help me with this, I would love to learn how to sort this out. I want to tag the transformer and store it for later use if possible.
Quite simple - I have connected it's primary to 18V secondary of another transformer (to avoid connecting to mains), and then measured voltage at it's secondary.
It definitely wasn't an old tube amp, just some kind of solid state, and could be distributed system. Transformer was connected to output jacks, and there is a switch near them with two positions: 100V and 8ohm. Maybe it was connected to the swithc, I am not sure.
Gotcha, just checking, you never know on this forum sometimes...no offence 😉🙂
Yep 100V line matching transformer
Yep 100V line matching transformer
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