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Chime Module exposed.


Machiner 55

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Guest Mc_Reatta

Other than the electrolytic caps, looks pretty bulletproof.

Did you discover the failure mode?

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McR,

No I haven't. The only thing I see that might have caused a problem is that one of the attachment lugs was cracked perhaps allowing the metal diaphragm to move out of position. I haven't looked at the traces and joints on the PC board under a microscope yet. May find something then. The one that I repaired years ago had a cracked solder joint on the bridge supporting the diaphragm assembly. I re-flowed the solder and it's been working ever since.

John F.

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Well,

that certainly isn't what I expected. It appears to be a hybrid electromechanical setup. I had always figured it was a small speaker (most likely a piezo element) with a small tone generator that had a decay circuit added to make the chime sound. This is something else again. The chime on my 88 is bad - I get a sickly squeal from it periodically, but that's it. Guess I am going in there and trying to fix it once removed. I rather suspect bad solder joints as the most likely failure mode. That said, the fact that there is some type of electromagnetic device involved has me questioning that hypothesis.

KDirk

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SeanR,

Yah, I failed to include a shot of the underside (may edit one in later) showing the traces and joints but, it's those joints (all of them are suspect) especially the ones connecting the diaphragm bridge to the board that need to be looked at. Just eye-balling them won't get it. A microscope comes in real handy for this job.

Thanks for providing the link.

John F.

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