whats your verdit - Sammy Juo Speaker issue

[kenshin]

i have a sammy juo machine, and I did the L-pad mod as was suggested with the 15watt ones from the parts express link.

I hooked up a mono one to the bottom speaker, and it worked great.

moved up to the top two speakers to do the same with a stereo l-pad.. wired it up, and nothing. no sound from the speakers. i checked with a multimeter to make sure the connections were right.

so i undid the wiring and rewired the two speakers back to the original wiring.... nothing :-( not even in BB mode when the music always plays

so the verdit - are my speakers fried? or is there some any alternative? i found out later these are piezo speakers, but will an l-pad really fry them?

[gwarzin]

Are you POSITIVE that they worked in the first place? Sammy tweeters are known for failing - or I should say, already being broken when they arrive. They fail in the parlors and few vendors even bother to check to see if they are working when they do the refurb.

I can't think of anything the L-Pad could have done to fry them.

I have not confirmed this, but I have been told that the common failure mode for these tweeters is for the mechanical stress of repeated flexing to cause a wire to break were it attaches to the moving part of the speaker element. Someone said they've fixed this by opening up the back of the tweeter and reattaching the wire.

I repeat, I have no first hand knowledge of this. The first thing I do when I get a Sammy is check the tweeters. If one is broken I just report it to the vendor and get a free replacement. I don't want to open the tweeter to try a repair and void the warranty.

BTW, these tweeters are so unreliable that I've actually had vendors send me broken ones as a replacement.

[cwstnsko]

Hopefully it's the wiring or the tweeters that are messed up and not the board. I'm not exactly sure how the tweeters look electrically, but I can tell you that I cannot measure a value for resistance in the tweeters on any scale of my ohmmeter. They measure like an open circuit on the 2000K ohm scale. I think the L-pad probably placed a load on the board of about 8 ohms which would have been dramatically less resistance and therefore more current then the board was designed for.

As far as controlling the volume in the piezo-tweeters, I can tell you that the potentiometers I have on mine are currently set as close to 2K ohms as I can get, and the range of volume available from the on-board volume switch is just about right to my liking. I'm planning replace the pots with a couple 10 cent 1/4 watt 2K ohm resistors and in the speaker wire then shrink wrap them. It should look real clean, be cheap, and be effective at "correcting" the volume levels, without subjecting the amp to too much abuse.

Update: Radio Shack had 2.2 k ohm resistors, so I put one of those in 1 wire of each of the piezo tweeters. Individually, they seem too quite, but when you get the machine up and running, it seems just right to me,

As for the lower speaker, you have already discovered the L-pad works great, as do proper resistor configurations.

[kenshin]

thanks guys, ill at least try to take apart one of the top ones to check for any loose components internally

i guess the bottom speaker is enough volume by itself, oh well :-?