• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Vintage 1990's Audio Note 2k5 output transformer wiring color code

I can't answer you directly because I don't have that transformer. But a good ohmmeter will get you there. Best is a four wire kelvin clip style meter. Furgetabout an el-cheapo import multimeter. However a good VTVM with close attention to zero setting on it's lowest range could work. First establish the end-to-end winding (most resistance). Then from the low end the 4Ω will be the lowest R. The 8Ω will be the other. For reference the progression (not actual resistance) will be something like 1-1.3-2
 

Tesla88

Member
2011-12-21 8:37 am
Italy
HollowState suggestion is correct, btw low resistances are hard to measure sometimes, so here's another way to do it :

i would inject some AC signal across primary and then measure output voltages across secondaries...

The higher value is 16 ohm output and should be around Vprimary / 12.5 , the 4 ohm tap should be half the 16ohm voltage , the 8 ohm tap is 0.7 of the 16 ohm voltage.

I would inject a large signal on the primary to reduce measure error.

Say 100Vac at primary (around 4W @2500 ohm ), you should read :

8V @ 16 Ohm (end to end) - those two leads are the end to end of secondary -take one lead as 0V reference.

5.656 @ 8 Ohm - if you read around 2.35V the lead you choose as referenze is wrong, take the other and check again for 5.656V

4V @ 4 Ohm

Since the transformer is unloaded, voltages could be a bit higher !

Apologies for my English :D