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Amplifier speaker relay problems.

Hi, I am working on an Niko Alpha II amplifier it is an older amp with the two large VU meters on the front. There is a problem when powering up that one chanel may not work. I have tracked this down to a relay that is in the speaker output path and is 24volt dc with two normally open contacts. It is on a printed circuite board and I wish to change it as cleaning did not help and I am afraid it may be degrading sound when working if not providing a good path. I uderstand this relay helps prevent thump on powerup and the sound from dithering out on shut down. Thank You for any advice.
guycom
dsrjohn
8 posts
 
Seems that I cannot add pics.
erik_squires
16,389 posts
 
What is the problem with simply replacing the relay?

Also, I've had similar issues with Yamaha's. While I was upgrading parts, I also used a relay socket. This lets you swap relays in/out quickly without resoldering. Relays have been standardized for a long time, so with a little luck you can find an exact fit.

The old relays I saw used convex curves which minimized contact area and had more reliability issues. More modern relays have matching concave / convex contacts which supply much better contact surface.

Best,

E


erik_squires
16,389 posts
 
Should also point out, you should not just replace the relay with a fuse.

The protection circuitry prevents turn on/turn off transients and DC protection which a fuse will not.
dsrjohn
8 posts
 
Realize that about the fuse. Just wonder if it is a relay issue or something upstream that causes the relay to engage. The contacts on the relay look perfect - gold plated and not dirty at all.
dsrjohn
8 posts
 
pics posted here
https://sound.stackexchange.com/questions/26998/what-is-the-click-noise-that-an-amplifier-makes-after-you-turn-it-on-off/42225#42225
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