1969 Zenith 25ZT120 - AM Drop-Out, Sticking Power Button Issues

[damen]

The tuning cap in your chassis is only for AM, the FM section uses coils.

[videoroot]

Originally Posted by damen

The tuning cap in your chassis is only for AM, the FM section uses coils.

Ah, that makes definitely sense then. Thanks again!

I'm still experiencing the same issue, but I think this is at least pointing me in the right direction. I pulled everything back out and cleaned it a couple more times. To my naked eye at least, it looks just about as clean as it's probably gonna get. At the very least, I can't visibly tell where it might be shorting now.

Now I'm wondering if the issue might be from some of the fins being bent? Some of the fins certainly appear to be touching the back plates as I turn it back and forth, although it sure is hard to tell just from sight alone.

Feel free to let me know what you think. I'll attach a few pics here. Tried my best to get them as clear as I could, but I'm sure you know how it is. Let me know if you have any issues viewing them.

Obviously, I'm gonna need to do more research before I jump straight to trying to bend them back into shape by hand.

[damen]

It's been my experience that most shorting plate issues happen on the very outside ones. Your gang has three sections. It may be necessary to disconnect any wires and use an ohm meter to determine which section the short is occurring. Disconnect and check each section one at a time. Also, if cleaning the power switch mechanism does not correct the sticking problem, I noticed the Sams diagram gives the same replacement part number for the stereo-mono switch as for the power. Maybe swap them till a replacement can be found ? When using the phonograph the power switch is not supposed to be pushed in anyway so that the changer will turn off the amp power at the same time.

[videoroot]

Originally Posted by damen

It's been my experience that most shorting plate issues happen on the very outside ones. Your gang has three sections. It may be necessary to disconnect any wires and use an ohm meter to determine which section the short is occurring. Disconnect and check each section one at a time. Also, if cleaning the power switch mechanism does not correct the sticking problem, I noticed the Sams diagram gives the same replacement part number for the stereo-mono switch as for the power. Maybe swap them till a replacement can be found ? When using the phonograph the power switch is not supposed to be pushed in anyway so that the changer will turn off the amp power at the same time.

I'll have to give that at try next time I'm working on it. Thanks!

Unfortunately, my power and stereo-mono switches are two different kinds of switches. It's entirely possible the one in my machine is an aftermarket replacement. That being said, I might explore swapping them in the future nonetheless.

Today, I bit the bullet and pulled all the old hot glue off of the power switch. As I expected, it's in pretty rough shape. Genuinely looks like someone took a hammer to it at some point (or chewed on it). After cleaning it and putting it back together, and it seems to be working much better now. I'm probably gonna end up using either hot glue or epoxy on it at some point in the future as it'll likely break apart again at some point in the future if I don't.