Seiko 690T Buzzing sound

[stmzu56]

Hello, I have a Seiko 690T that makes a buzzing sound after it's been plugged in for a while, maybe 10 minutes or so. It started after I accidentally knocked the clock onto the floor. I'd like to fix it, but I don't know anything about the inside of clocks.

[Mackey]

It's hard to say what might be causing that. I'd be glad to take a look at it for you.
PM sent.

[Mackey]

This is what the clock sounded like



The above is recorded from right next to the clock. The following is from 3 feet away.... Clearly something had to be done. (if you listen you can hear it flip).



That's not the alarm ... that's the clock vibrating. It's related to the alarm ... I'm going to try to either do a video or an explanation of why this happened. It's fixed by the way ... but I've got to make sure that it's a permanent fix before I send the clock back.

[Mackey]

So here's what's going on -
the copper wire windings that set up a "rmf" (rotating magnetic field) to make the rotor part of the motor spin, are the same that the clock uses to make the vibration for the alarm. It would seem efficient to do that, but it also seems primitive in a way. There are four bars that come off those windings - two make up the arch that set up the rmf and the other two the vibrating arms. These arms are typically kept apart mechanically except when the alarm is set to go off. They are then allowed to move closer together which sets them to vibrating, causing the buzzing sound. When this clock was dropped it seems that the concussion ever so slightly upset the balance between these two sets of bars. This resulted in one of the bars basically acting like a tuning fork and just vibrating, which reached it's peak as the clock warmed up and reached it's max operating temperature. I am suspecting that this may have resulted in a negative impact on the rmf which caused the clock to run slower.

You would think that the two arms making up the alarm had pushed closer together .... but this was not it at all. It was just a harmonic thing or something.

All I did was loosen the motor mount screws (which go through the two arms making up the parts that set up the rmf) then re-tighten them carefully. It's been running 12 hours now without the buzzing and keeping good time.

I'm going to make a video about this. I also want to discuss other things about this clock (I've wanted to see this model for a while) because the clock was actually never intended for the US market.

Anyway, more by the end of this weekend.


Here is stmzu56 's clock this morning. I'm supposed to be getting ready for my day (that's my work laptop), but here I'm am messing with flip clocks. (and yes, I'm on the clock!!).

[Mackey]

Update: Well .... I thought it was all good. Adjusting the alarm arms did quiet the clock considerably, but there remains this chronic, light hum. I tried recording it from 3 feet but you could hear other clocks in my home more than the buzzing. ... but it's still there. Not sure if it's a deep problem in the motor from the fall or what, but I'm not comfortable trying to open that up to find out.

Before at 3 Feet


Now at 3 Feet

[Mackey]

It's not bad. Going to send back and see what the owner thinks.

View Video

The Seiko DP 690T Flip Clock Alarm フリップクロック