Adding a protection circuit to an Eight?

[KeithD]

Has anyone either added a protection circuit/speaker relay to an Eight that does not have one, or transplanted one from another unit? My Eight does not have the protection circuit/speaker relay that the late versions of the Eight had. Just wondering what it would take to add that feature to my unit?

 

[sanjib]

Keith
Here is the post by Randy for making relay board
https://audiokarma.org/forums/index.php?threads/sansui-eight.844288/page-6

 

[KeithD]

Keith
Here is the post by Randy for making relay board
https://audiokarma.org/forums/index.php?threads/sansui-eight.844288/page-6

Yes, I was aware of that thread, but he never did post the schematic of what he ended up using for the circuit, and I don't quite follow where all the connections go for the board he made and the relay.

I wonder if anyone has a schematic that shows the factory protection circuit Sansui used on the later models, or if someone has transplanted one and how they did it?

 

[sregor]

There are Amazon, EBAY (and other places) already made boards which cost about as much as the parts do, and are pretty much plug and play.
Amazon https://smile.amazon.com/s?k=upc1237+relay&ref=nb_sb_noss
EVAAAY (some require assembly) https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=upc1237+omron&_sacat=0
Some require AC (on board regulator) some require 12V DC.
You may have to do some thinking on power - (simple is a small 12 to 24 volt transformer)
YMMV My 2 cents.

 

[KeithD]

There are Amazon, EBAY (and other places) already made boards which cost about as much as the parts do, and are pretty much plug and play.
Amazon https://smile.amazon.com/s?k=upc1237+relay&ref=nb_sb_noss
EVAAAY (some require assembly) https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=upc1237+omron&_sacat=0
Some require AC (on board regulator) some require 12V DC.
You may have to do some thinking on power - (simple is a small 12 to 24 volt transformer)
YMMV My 2 cents.

Interesting, have you used any of these?

 

[mbz]

I've used the original version of this,
https://www.ebay.com.au/itm/NEW-ver...reo-Speaker-protection-board-LED/121976465411

in about 10 smaller amps, it's a little dated, many different types, the uPC... are a good cheap buy.
Provide basic power on/off mute and excessive Vdc detection.

I always fit a separate 240Vac/12Vac transformer to power the board, total cost of board/traf about AUD20-

 

[sregor]

Interesting, have you used any of these?

Don't recall which one (they are all pretty similar) and it was a couple of years ago...was one of the ones which had on board regulator and only required the AC to run. One of the secondaries was 12 v AC...

 

[Skywatcher]

Interesting, have you used any of these?

I have, but not on your receiver. They work alright. You don't have a place to tap voltage from that is adequate to run the board, and there are very small AC to DC out power supply boards you can use. Just tap the AC right from a convenient spot, perhaps a switched outlet, then run the DC out to the relay/protector board, and of course reroute the output from the amps (keep the fuses in the circuit) through the relay board, then to the speaker switch.

 

[KeithD]

Thanks for the insights, guys. There's not a lot of spare room inside the Eight. It would have to go in the underside, and getting a commercial protection board and AC/DC PS board might be tricky. It still makes me wonder what the protection board looks like on the versions of the Eight that had a factory speaker protection relay.

 

[whoaru99]

There are Amazon, EBAY (and other places) already made boards which cost about as much as the parts do, and are pretty much plug and play.
Amazon https://smile.amazon.com/s?k=upc1237+relay&ref=nb_sb_noss
EVAAAY (some require assembly) https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=upc1237+omron&_sacat=0
Some require AC (on board regulator) some require 12V DC.
You may have to do some thinking on power - (simple is a small 12 to 24 volt transformer)
YMMV My 2 cents.

Interesting, have you used any of these?

Have not used any of those, but I built one using the board from DiyAudio Store. Unfortunately they only sell the protection board as a pair with the soft start board so if you don't need/want the soft start there is that.

I built it into a project box and put binding posts for the input and output connections, along with a coaxial power input connector. It runs from a small wall wart connected to a switched power plug on the amp.