Identify Color code for OT push pull.

[bluetube]

Good people, I was wondering if I may ask for help indentifing the wires of this OT I picked up. It is from a Pioneer stereo receiver from the 60's. Two OTs inside with four EL84 and a massive PT. The wires were cut, so I am a bite loss. This is new territory for me. Need a little help to get started. Thanks in advance.

[tedmich]

Originally Posted by bluetube

Good people, I was wondering if I may ask for help indentifing the wires of this OT I picked up. It is from a Pioneer stereo receiver from the 60's. Two OTs inside with four EL84 and a massive PT. The wires were cut, so I am a bite loss. This is new territory for me. Need a little help to get started. Thanks in advance.

here are some links to RMA color codes on transformers, and some transformer info. The side with 3 leads is likely the input (primary) as an ultralinear PP input would have 5 leads. The max DC resistance measured identifies the output tube connections and the B+ tap will have ~1/2 the resistance to each primary. Similarly the DC resistance will be small on the output (secondary) leads and the shortest one (green?) may be the ground; each tap will be ~2 fold higher resistance for 4/8/16 ohms. The polarity of the output signal in a functioning amp will let you know if the primary polarity it right; positive feedback sounds quite bad.

Integrated Publishing - Educational Training Manuals

Output Transformer Impedance

http://www.tech-systems-labs.com/pdf...nformation.pdf

http://www.radiodaze.com/catalog-306-colorcode.pdf

Vintage Radio Troubleshooter's Handbook CD

Notes On Servicing Radio And Sound Equipment

[stokes]

On the primary side,the 3 wire,the red is your CT the other 2 connect to the plates of the power tubes.On the side with the 4 wires one is going to be the ground connection.The green and yellow are likely speaker "hot" connections,possibly 4 and 8 ohm,so that leaves the white and I cant tell what color the other one is,as your ground connection.You would have to measure the resistance from one of these to the other 3 to determine which is the ground.You will have to determine the turns ratio so I would go straight to that test to sort things out.To do this you need to connect a signal generator or a variac to the primary outside wires.I cant tell the colors but these would be the 2 that arent the red one.Put a half volt ac on these two and then measure the ac voltage at the secondary connections using either the white or the other one as the ground and post back with the results and we can sort it out from there and I will explain how to get the turns ratio and which connection is the 4,8, and 16 ohm connections,assuming that is what they are.Could 2,4 and 8 ohm or something,but we'll cross that bridge when we get there.