Help Identify a Transformer

Hello Everyone,

I have a power transformer out of an RCA 6 channel HT amp and would like to use it with Brian's LM4780 kit. It has the following numbers on the top:

ks olt st

It has 3 thick wires that are red, yellow, red and four smaller wires which are Gray, Orange, White, Orange. I beleive I will connect the thre thicker wires to the power cord and then the four smaller ones to the power supply boards, but where?

Also I plan on using 3 seperate chasis, one for the transformer and power supply boards and one for each amp section. Is it ok to use heavy gauge electrical cord and plugs to "plug" the amplifier sections into the power supply section? Also should I put the power supply boards with their respective amplifier boards or keep them with the transformer?

I appologize in advance for all of the questions.


After pulling up nothing on dogpile I figured this would happen. I have just received 2 multimeters, is there any way to use these to check the voltage and amperage? Can I hook up the red and black wires to a power cord and then measure the output on the other lines? Anyone have any suggestions?




diyAudio Moderator Emeritus
2002-06-10 12:01 pm
Don't connect anything to the mains until you have a fair idea which winding is which.:att'n:

You mention a black wire in your second post, but not in your first.

When you say "thick wires", do you mean the wire gauge, or the insulation, or both?

Measure with your newly acquired multimeter between each wire using a lower ohms (resistance) range and report the measurements.

The primary will probably have a resistance of a few 10's of ohms.
The higher powered secondarys will have a resistance of a couple of ohms or so.

When you eventually connect to the mains, do so with a fuse in line. 500mA to 2A will protect the transformer and your house supply. Do the work away from earthed or metal cased objects, and wear synthetic soled footwear.
Most likely, the four thinner wires are two parallel primaries, and the red-yellow-red is a center-tapped secondary. Use the multimeter to see which primary wire is connected to the other. IE, have the meter set to resistance, and put one lead on the grey wire. Touch the other lead to both orange wires and the blue wire. Two should show a very high or infinite resistance, and one should show a resistance of a couple ohms. The one that reads a couple ohms is the other end of the lead your testing.

Since you're in the states, you'll want to wire the two primaries in parallel. Once you know which wires belong to which primary, hook them together. So, if one primary is white/orange and one is blue/orange, hook up the two orange together, and the white and blue together. It would be better if you had a lower voltage supply, but if you're careful you can tie the orange/orange to one side of a mains line and the white/blue to the other. When you do, have your multimeter set to measure AC voltage, and measuring the voltage between the two thick red wires. If it's below say 15V, switch the primaries so that orange is connected to blue and the other orange is connected to white. Try again and see what the voltage is. Should be higher this time.
Thank you both very much for your help. I will measure these lines when I get home tonight. I did make an error and the 3 secondary lines are red yellow red and the four primary lines are gray orange white orage. I have a work area with a thick 3m anti static mat on the top and another on the floor, they are supposed to be electrical proof, do you think this is sufficient protection along with synthetic soled shoes? Also since I have 3 secondary wires and I see I will have to split them to go to the two boards is it ok to use a terminal strip or would it be best to solder them directly?

Thanks again for your help.
Your antistatic mat is not an insulator, it is conductive. The antistatic mat takes care of static by spreading any discharge and shunting it to ground through a resistor. It is no help at all. Neither are your shoes. You can be totally isolated from ground, but it you touch one thing with your right hand that is at a different potential than your left hand, the path for current is through your heart and potentially fatal. The message is: if you don't know what you are doing, it's best not to do it. Electricity is dangerous and should be treated with knowledge and respect.

if you do not have access to a variac, maybe you own a small voltage transformer you could use, such as one for desktop speakers, mobile charger or the like.

I'd take KiloWattski's advice serious.
A couple of years ago i bundled up, touched a hot wire while i was sweaty. The sparks popped out of me, making 1/10" black holes in me. The cardiologist told me i am a LSOAB, i had heart rithm problems long enough to keep the memory alive.
If you are already that hot, no need to torch yourself. :clown:
Thank you both for your advice. I will be much more careful from now on. My father owned an electronics repair shop and he, and I since he was teaching me, never took very many precautions. Of course my father had so much current in him that he would arc to shopping carts and car bodies some times:) I tried to measure the wires this weekend but my multimeter is not working, going to ratschack to get a new fuse tonight after work. But while I was looking at this transformer again I found that there are more wires, cut short, on the other side and some more numbers.

NS-8408 7136CSMD

The wires are Blue and Black of a larger diameter and Blue Black Blue then Green Brown Green of a smaller diameter.

Any advice?:D
transformer I.D

I also need help with Transformer.
It is marked:GA-6097
It cam e out of Vintage Yamaha Natural Sound Amp.
There are two leads coming out of one hole in casing. They are Brown and gray. I am almost certain they are 110V mains. Resistance betwwen the two is 3.2Ohms.
Out of the other hole in caing are: 2 Red, 2 White 1 Black and 1 Yellow. I would like if possible, to use this Transformer in Building a biploar 18V power supply, hopefully get 48V and 5V as well. Good Clean bipolar 18 is priority
Hello Audio Gurus:)

I have some measurements.

Red .4 when connected to yellow, .5 when connected to red
Red .4 when connected to yellow, .5 when connected to red

Gray No measurement
Orange 1.3 when connected to other orange
White .8 when connected to the orange below

Black 1.0 when connected to Blue

Green .8 when connected to the other green
Brown .5 when connected to either green

Blue 1.0 when connected to the other blue
Black .7 when connected to either blue

All measurements were made on the 200 ohm setting with the probes in the com and Vohm spots.

Anyone have any ideas? Also how good is it to use this type of powersupply with a chip amp? I found an electronic surplus yard (absolute heaven, heatsinks, xformers, speakers, caps the size of grolsch mini kegs, you name it they have it floor to celing for dirt cheap) and they have 1000's of these types of transformers up to 10,000 volts for very cheap prices. Any advice?