Now that the main chassis and tuner unit are complete, i will require a speaker to connect to them when i do the alignment.
So it is time to tackle the speaker.
This radio came with an original electro-dynamic speaker, part number 7255903, this one is completely rotten and frozen with rust and dirt.
A side note - There is some evidence that later on these radios came with a PM (permanent magnet) speaker.
If you find a PM speaker (possibly part 7256355?) in your radio it could be the original too. If the pole magnet is too weak you can order a replacement magnet when rebuilding a PM speaker.
After carefully extracting the voice coil (because i might reuse it), I pressed out the pole piece. It presses out relatively easily from the back side towards the front while supporting the top plate with a large socket or pipe.
Once the pole is out, the field coil slides out with the cardboard shims and the copper plate.
I am not certain about the thick copper plates purpose. Either is is just a gap filler or the designers were getting fancy and thought this plate could be a 1 winding shunt for any AC ripple current presented to the field coil.
Either way, it will be going back in, it's 1/16 thick and is needed to keep the field coil tight.
The original voice coil seems re-usable, however the paper may continue to warp so i will order a new one and decide which to Using paper shims to fit the original voice coil snug onto the pole I measured it's ID. (this way i know it's round and not oval)
I will order a new mylar backed 1.000 ID voice coil which is probably what this original coil is suppose to be.
The spider cup needs to be about 2.2 inches in OD and about 0.2 inches high.
The closest size to get is 2.171 OD x 0.197 height, I prefer to go the nearest size too small, as anything too big just never fits well and flat.
For anyone else who is rebuilding new or old speakers, my source for parts is The Speaker Exchange
https://reconingspeakers.comThe next post will be re-assembling the speaker, and i will include the specific part numbers for the replacement parts used.
-stan
