Mesa stiletto loop died!!!!!

[tim seebran]

I've had a mesa boogie stiletto trident bout a year now . love it . i ve been using the effects loop for delay , eq. and a sonic maximizer. tone galore ! now my loop does not work . it picks up a signal but its faint. i ve already changed the tubes especially the no. 4 12ax7 preamp which the owners manual sais runs the loop. and also i changed out all the other tubes to check. nothing doing . any help? thank you.

[soundguruman]

It may or not be, depending on the construction...
There are two possibilities, and I am making an educated guess, first the LDR, light dependent resistor, or relay, I don't have a schematic.
Some models use LDR, some use mechanical relays.
Then second the FET transistors. Yes there are plenty transistors in Mesa amps.
If we had a schematic to look at it would be easier, so find one and post it here.

[g1]

schematic links here: The Boogie Board • View topic - Stiletto schematics

[Jazz P Bass]

Well that is confusing.
What is Mesa doing, switching the FX loop on & off?

[soundguruman]

Well that is confusing.
What is Mesa doing, switching the FX loop on & off?

It's a mute, and a butte, too.
Sometimes that type J175 may need to be replaced, because FETs can go bad.
Take the FET out, and see if the level comes back.

[tim seebran]

ENGINE ROOM sendspace.com/file/p9i1rk

[tim seebran]

ENGINE ROOM sendspace.com/file/p9i1rk . found the schematic. i ve got the output board removed i figured it was one of those transistors or resistors or capacitors . they re fairly easy to replace just gotta find em. thanks for any help.

[soundguruman]

Well that is confusing.
What is Mesa doing, switching the FX loop on & off?

I think the genius idea is to mute the circuit so it won't POP when it's switched?
Fender did a similar thing, but it works better if you take it out.

[soundguruman]

Captain, she's going to blow.

[mikeboone]

Digikey and Mouser both have that The J175. My Single Rectifer has an issue with low output. Someone in a thread suggested I try that. It didn't fix it, nonetheless, that's where you can get the part.

[soundguruman]

Digikey and Mouser both have that The J175. My Single Rectifer has an issue with low output. Someone in a thread suggested I try that. It didn't fix it, nonetheless, that's where you can get the part.

Take the FET out. Now test the amp. If taking the part out fixes the problem, then you can replace it, or just leave it out permanently.
The amp will work without it.
Replace it, and it will probably fail again in the future.
Several amps, including Fender used FET for a "mute" circuit. It usually works better without it. No kidding.

[mikeboone]

I'll give that a shot. Thanks!!!

[soundguruman]

you "could" actually clip two of the leads, and then test it. The leads can be soldered back together.
These circuit boards are a royal pain to work on. FETs are static sensitive, so you will need a static safe soldering iron.
If you do not have a temperature controlled soldering station, find somebody who does.

[tim seebran]

you "could" actually clip two of the leads, and then test it. The leads can be soldered back together.
These circuit boards are a royal pain to work on. FETs are static sensitive, so you will need a static safe soldering iron.
If you do not have a temperature controlled soldering station, find somebody who does.

thanks . will give it a try.

[tim seebran]

thank you soooooooooooo much, it worked !!!!!! it actually sounds better or maybe it was the 3 weeks without it. ?it seems to have more bite through the loop. you saved me much downtime and shipping costs thanks mr. soundguruman. what is the purpose of the fet j175 anyways? also im building a custom les paul style guitar peruvian mahogany, neck thru, one piece body ex. fret board, with a piezo bridge grestch electromatic humbucker (bridge) guitarheads stacked single(hotrails) neck, 3 way toggle, vol, and tone.i want a full humbuckersound in the neck position split coil in the mid (neck south coil) ,and full humbucker in the bridge position and to be able to blend the piezo with any toggle position. (not asking much)? no coil split sw. any body out there know how to wire ?cant find a diagram.