Speaker Relays

[JacTaylor]

I'm not sure if this is a common problem but it seems to be with my limited exposure to 70s receivers. I purchased a Marantz 2252b and cleaned the heck out of the pots and I still had this requirement to increase the volume to prevent the fade out of one channel (right in this case). After searching a bit, I cleaned the speaker relay with small strips of business card paper/deoxit and that did the trick. This segue to the KR-9600.

After restoring the power amps, power supplies/resistor mod and switch mod, I still had a similar problem with the Kenwood. At low volume, one channel just kind of fades out (again right channel). So I replaced both speaker relays with new ones and that again took care of the problem.

I guess from reading, these relays after 40 years tend to wear out, too? Although, I've also read, they are one of the most reliable parts. At any rate, they're insidious in the way they creep into some of the problems that crop up.

 

[JacTaylor]

I understand, that makes sense...why a volume increase helps. These were about 30 bucks for the two with shipping. That's quite a bit cheaper!

 

[JacTaylor]

Just put an offer of 2.50 for 10 with 16 shipping...still about 4.2 each. Thanks!1

 

[JacTaylor]

Stated more than 10 available but I guess I bought him out.

 

[dr*audio]

They don't wear out, they get oxidisation on the contacts & the resistance just increases. all you really have to do is clean them with really fine sandpaper like 800 or 1000. The covers come off easy. New is always better, just bought 10 idec NOS versions off ebay @ 2.75 each, u can't get them that cheap anywhere.

WRONG! NEVER use sandpaper on relay contacts! You remove the plating on the contacts that keeps them from oxidizing, and then they rapidly oxidize. Within a month that relay will be intermittent again. I learned this by painful experience, getting recalls on units I repaired. The contacts DO wear out, the plating gets worn and the contacts start to oxidize. There is a small amount of rubbing that takes place when the relay opens and closes that causes wear. Also a small amount of arcing from turn off transients in the amplifier. You can see the worn portions under a microscope. I also originally thought I could check if the relay was good by tapping on it to see if the channel dropped out. I missed a couple bad ones that way. No more! All speaker relays get replaced in older equipment.

 

[JacTaylor]

Thank you...good to know. Whether it's some deal on the Bay or known quality from DigiKey, small price to pay for perplexing problems due to old relays.

 

[dr*audio]

Get off your high horse dr.*audio! Very fine sandpaper works fine on relays, they will last for years. New is better but this works fine when can't find the correct relay. I was talking about the mechanical operation of the relay that doesn't wear out, no that doesn't! I know of many people including myself who refurbish a relay this way when one isn't available. Not much arcing going on with speaker protection relays unless you have the volume turned way up when it's turned on, power relays yes. I you see arcing on a speaker protection relay then you have a problem for sure. "Within a month that relay will be intermittent again"? Not in my experience, a KA 8004 that had that done 20 years ago. What do you think happens to the "plating" after 6 months of being turned on & of anyway? You are just nit picking a thread about speaker protection relays & it's rediculous!

I am not nitpicking and I am not going to argue with you. I have 40 years of experience professionally repairing this equipment. I can not allow something to leave my shop that might come back in a month with a problem. If the relay can't be replaced with one with the same footprint, I adapt the board so a modern replacement will fit. No excuses, no exceptions, no recalls. If shoddy work and cutting corners is good enough for you, that's your business.

 

[tarior]

Never use sandpaper. If you have a relay that is something special, clean the contacts with Flitz. If they don't come perfectly clean, no pits, no dark spots, with Flitz (or similar chemical product), then it must be replaced. Sandpaper, even 1000 grit or higher is bad juju.
For me, the time it takes to desolder the relay, take it apart, clean it, inspect it, put back together, and solder it back in, I'm $ ahead just to slap in a brand new one.