Echoplex EP-3 Questions

[mort]

I just traded for 2 Echoplex machines that each need service. In order to keep things tidy I'm only going to mention 1 issue at a time and will edit this post to show what is currently being asked and what has been accomplished.


Red Panel EP-3 serial 9607
The magnetic coil that pulls the pinch roller bracket gets 160vdc and energizes on start up but de-energizes after a minute or two. 160vdc is still present measuring directly at the coil nodes during the failure mode. Do I just need to find a new coil?


Gray Panel EP-3 serial 12834

[Enzo]

Volts across the coil is what matters, not voltage ON the coil.

[mort]

Volts across the coil is what matters, not voltage ON the coil.

Right, one meter probe on one node, and the other probe on the other node. (not from ground to node)

[Helmholtz]

Measure the DCR of the solenoid, one end lifted from circuit.

Schematic?

[mort]

Updated first post with schematic.


Sometimes the coil energizes again when the chassis gets a smack with the plastic end of a screwdriver. I think it's got an intermittent open short in it. Or at least that's how it seems to be acting.

[g1]

When you measure the 160V, are you on the solder pads (assuming the relay is board mounted)? If so, it could be bad solder or a cracked leg on the relay.

[mort]

When you measure the 160V, are you on the solder pads (assuming the relay is board mounted)? If so, it could be bad solder or a cracked leg on the relay.

Reading directly on the coil nodes.

[52 Bill]

I had one that had an intermittent coil that would open when it got warm. The break was right at one end of the coil wire where it soldered to the terminal. It's really just a simple coil winding.

[mort]

A little update. Figured out that the circuit surrounding the coil was not at all like what's on the schematic, it looked like non-original work, so I configured it to the drawing and replaced the 20uf cap because it was dead. Thought I had it licked but the coil is still intermittent. Perhaps the faulty work caused the damage to the coil.

I'm not opposed to attempting to rebuild the coil but how do I get the coil casing apart without destroying it? I can post photos later... but there are metal tabs that get flattened with a hammer to hold it in place. And it's thick metal. And it looks like one end of the core gets punched as well, which makes it appear very difficult to remove without causing irreversible damage.

[wsscott]

I'm helping a buddy with an EP-3 that he recently got for free, and have an issue with the motor not starting up spinning after I replaced the belt. I know this post is about the solenoid mechanism, but I can't figure out how to start a new post. Can someone point me in the right direction. The motor is fine with no belt, but I think the flywheel has too much drag in its bearings so the motor can't get started. Thanks.

[g1]

Up near the top left of linked page, there should be a 'new topic' button:
https://music-electronics-forum.com/...guitar-effects