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AU-717 Relay Confusion

Sriskie

Sriskie

Well-Known Member
I'm rebuilding a very nice AU-717 and have a question about the replacement relay.



I see most are using a MY4 style but the one I removed is a MY2. I have both a MY2 and a MY4 on hand and it looks like either will fit but I'd need to clip a couple of unused leads on the MY4. The extra pins between the two types share a common trace so it seems either should work.



I guess what I'm asking is, do people use the MY4 in order to facilitate the use of an extra set of contacts for reliability or is there something else I'm missing?
 
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the MY4 is marginal on contact current carrying capacity (3A against 3.26A at 85W into 8ohms) and has a shorter endurance capability than the MY2. Take a look at the attached data sheet.

FYI...
 

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Thanks!

The parts list I used and other threads I found mentioned using a MY4 so I thought it might be some kind of a performance upgrade or something. I'll go ahead and use the MY2 which is great news for me. I have 8 MY2s in stock and only 1 MY4.
 
The MY4 is the one to use. The MY2 is rated for 5A per contact, the MY4 rated for 3A per contact (6A per channel). If you consider AC carry-current (not on spec sheet, unfortunately), the MY4 outdistances the MY2 by quite a bit.

Not sure how the MY4 is 'marginal'. It's the relay used in the SX-1250 (160WPC).
 
That's great information to know EchoWars, thank you. I suspected there was something like that going on.

So the MY2 is good enough but the MY4 is more gooder. I'll go with the MY4 then.
 
EhcoWars- Sound logic since the MY4 has 2x the number of contacts even though the per contact rating is lower the overall capacity would be higher per channel.
4PDT vs DPTD

Presume the MY2 works well in an 85w amp since most people will never drive the amp at 100% duty cycle for any length of time. Still the MY4 would be an upgrade for certain.

Thanks for the clarification Echo!
 
from post #1 "I have both a MY2 and a MY4 on hand and it looks like either will fit but I'd need to clip a couple of unused leads on the MY4."

If you clip leads/pins off you're losing contacts. You'll only get the 6A carry capacity of the MY4 if you use two contacts in parallel for each channel ie you need to make 2 pairs out of the four pairs of contacts..

The MY4 works in the SX1250 because it's protection board has the traces needed to parallel the contacts so providing the 6A carry capacity.. It sounds like the unit you're working on doesn't have traces (because it doesn't have through holes) so you'd need to find another way to parallel them or settle for a 3A rating.. or use the 5A MY2?
 
The leads I'll clip are unused either way. They're the ones on the outside of the relay. There's no traces on the circuit board there. 2 have holes, 2 don't. There are traces for the 4 contacts though. 2 per side share a common trace so I'm assuming both relays will work.

In other words...

All of the contacts are double sided. This amp doesn't use the ones one the outside (or the far end) which is where I'll clip the leads.
 
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