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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

Showing 7 responses by dsrjohn

dsrjohn
8 posts
 
Seems that I cannot add pics.
dsrjohn
8 posts
 
Not sure anyone will respond but...A friend has a Sony TA-F3A amp. She says it was acting up - i.e. after powering up, it would take quite a while before she would hear the characteristic click and she would get sound but now it never clicks. Sounded like a relay problem. So I opened up the relay, blew some contact cleaner and that did not help. The contacts look to be gold plated so they shouldn’t even be dirty. I removed the little spring (see the pics) and sure enough, the contacts look very clean. Next test was to see if there was any sound - so I added a source and listened through earbuds. No sound. However, if I manually (using insulated pliers) flip the contacts in the relay so that they make contact, I get good sound out of the earbuds. So for some reason, the relay will not flip. It does not seem to be because of a problem in the circuit, as I get good sound out of it. So either the relay is gone or something upstream of the relay is gone. Any ideas?
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
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
 
Why that one?
dsrjohn
8 posts
 
Thank you. Will look into it.
dsrjohn
8 posts
 
Tried replacing cap C308 with several dif 100 uF caps but doesn't work. What would be the next thing to try? If I manually join the contacts in the relay, I get sound out of the speakers so it is something upstream from the relay. Maybe the relay needs replacing?
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