AC2300/S-5327

Thursday, October 28, 2021

Speaker

 There are these options when dealing with a vintage speaker:

1. Speaker OK to continue on
2. Speaker needs some work (repair cone...)
3. Speaker needs a re-cone
    a. Re-cone speaker
    b. Replace speaker

The speaker in this radio fell between #2 and #3. It has a warped cone causing the voice coil to rub on the armature. I decided, because this speaker is a fairly common size of 6" x 9" to go ahead and replace it. I found an NOS Radio shack speaker on Ebay that had one little tear in the cone that was easily repaired.


Checking new speaker fitment















Tuesday, October 12, 2021

Filter Capacitor Recan

 

Bottom chassis mounting
Top mounting

Filter capacitor can removed from chassis

Grinding the bottom crimp away

Crimp removed

Mounting ring removed

Terminal plate removed

Everything cleaned up and ready for assembly

Assembly fitting

New modern capacitors selected

New capacitor wired up to terminal plate

Testing the wired assembly

Completed and assembled filter capacitor

Testing completed filter capacitor




Monday, October 4, 2021

Transformer Fun

The next step is to rewind the primary of the power transformer to convert the radio from 6 volt to 12 volt. First some pictures of the state of the chassis..







Disconnect the transformer wires to remove it...

Transformer out of chassis.

Remove the rivets holding it all together.

Starting to remove the "Es" and "Is".

Es and Is removed. Note all the rust.

Removing the connecting wires.

Transformer core ready for the primary wire removal. But, first there is something odd here...

The primary winding appears to have two windings. Is this because it can be connected up as a 6 volt or a 12 volt? Some research is in order. I measured the wire to be 0.028", that equates to around 21 AWG with an area of 0.41 sq. mm. Double that up and you get 18 AWG with a sq. mm area of 0.823.



Thinking this may be the way to go...

Decided to connects lead wires to each lead so that the transformer can be configured for 6 volt or 12 volt.

Here are all the E's and I's after removing the rust chemically. My plan is to go over them with steel wool and then retreat them with an iron oxide chemical.

Decided to assemble the transformer and do some transfer testing. Without doing a bunch of fancy math to determine the exact transfer because I don't know the exact turns ratio I ballparked it. I hooked up my signal generator to the secondary and measured the voltage via a scope on the primary. The relative difference between the 12 volt and 6 volt configuration should be 1/2 which it was. The ballpark transfer should be 6 volts to 250 volts, primary to secondary. 250 / 6 = 41. On the scope I had to reduce the voltage scale by 10 and divide by 4. Close enough...

I the process, I updated the leads to colors...







Completed power transformer








All Done