5150 issue

[Anonymous]

i sent some pm's out to no avail.

anyone ever see this happen?

http://www.fjamods.com/phpBB3/viewtopic.php?f=11&t=171

i have this exact same problem...no sound. was playing, heard a pop, and it died.

-opened it up, took a peek, and noticed this same cap was oozing out onto the board.
-also, my lead channel LED light blew out when this happened.
i replaced that and ordered the same rated cap..installed it...still no sound. neither have blown out again, but, still now sound. the cap is expanding slowly though, as i've had the amp on for a few mins to see if it would produce sound.

-swapped out all my tubes. still, no change. nothing.
-checked every component on the preamp board for bad solder joints, and found one suspect resistor solder joint, fixed that..upon closer look, there's definitely been some previous work to this amp before i got my hands on it.

-amp only will provide sound if the guitar is plugged into the preamp out, and at that, it's pretty weak.

-after it first happened, it was providing sound into the effects return, but now it isn't after i replaced that cap.
-all fuses check out and are good.
i notice too, my PI tube gets pretty heated, and so do the output tubes (like they've been played for a good while on above 2 volume on either channel)...but none of the other 4 preamp tubes get warm even.

anyone?

 

[Anonymous]

nobody?

 

[andwhatnot]

I owned one for a while and beer had anything like that happen to me, or on any other amp. Good luck with that, sounds like a more expensive repair job than just the typical repair.

 

[glpg80]

Well, looking at a schematic i would question C46, C9, a transistor, a resistor, and your LED.

Regardless, the amp is also long over due for a recap - the reason you're in this predicament.

The reasoning behind all of this is a very complicated but i am confident those are all damaged or questionable. Had the chassis not been properly referenced to ground you'd been hit with 24V at about 1 amp - enough to do serious damage.

As it is i would suggest not powering the amplifier up and taking it to an experienced technician to do the repairs and continue troubleshooting. the filament supply and shorting capacitors due to age is nothing to mess with at all.

 

[D-Rock]

That sounds like what happened to my Soldano. Playing, then pop and the amp was gone. Only a very faint and weak signal could be heard if played.
The power tubes failed and took out the OT. Which can happen.
That fried a couple of resisters and two of my caps were leaking. Although the amp is a 2001 model so that contributed.
A tech needs to check your OT, me thinks.

 

[Anonymous]

Ot works. Otherwise it wouldnt be putting out sound and one or more fuses would b shot. Power tubes are fine. Checked em in another amp. Thanks fellas.

 

[Anonymous]

hey yeti..
i am having amps problems too.. with my 6505.. i went back and wanted my amp stock so went and removed the r9 and solver mica, and when i turned on my amp, well it sounded like complete shit... like it was shorting out,, and sounds dead quit.. i can strum a chord and it will produce a little but of sound but not much.. but when i mute the strings it sounds awful, its hard to explain.. i think the r9 isnt getting a good connection.. and making the amp short in and out.. i plugged into the effects return and it sounded good.. ive tried to resolder the joint on r9 but i cant get it.. and if i keep trying im afraid i will fuck it up more.. so im taking it to my tech today which lives 1 hr from my house.. that sucks.. but im going to have him do the bias mod, Restructure the gain - reduce the fizzy/fuzzy/buzzy qualities while retaining the high gain/distortion
All gain is useable - No matter how much gain you use you can still hear all the notes within the chords.. and try to make the amp a little tighter.. or i might just leave it alone after the bias mod.. i might like it better after that.. but man sorry to hear about your amp.. let me know if ya need anything.. because you sure helped me and i thank you...

 

[Lord Toneking]

Call Peavey and talk with one of their techs. I had problems with my 5150 and the guy I talked to there was super cool and spent alot of time on the phone with me. I wish I could remember his name

 

[Anonymous]

hey yeti..
i am having amps problems too.. with my 6505.. i went back and wanted my amp stock so went and removed the r9 and solver mica, and when i turned on my amp, well it sounded like complete shit... like it was shorting out,, and sounds dead quit.. i can strum a chord and it will produce a little but of sound but not much.. but when i mute the strings it sounds awful, its hard to explain.. i think the r9 isnt getting a good connection.. and making the amp short in and out.. i plugged into the effects return and it sounded good.. ive tried to resolder the joint on r9 but i cant get it.. and if i keep trying im afraid i will fuck it up more.. so im taking it to my tech today which lives 1 hr from my house.. that sucks.. but im going to have him do the bias mod, Restructure the gain - reduce the fizzy/fuzzy/buzzy qualities while retaining the high gain/distortion
All gain is useable - No matter how much gain you use you can still hear all the notes within the chords.. and try to make the amp a little tighter.. or i might just leave it alone after the bias mod.. i might like it better after that.. but man sorry to hear about your amp.. let me know if ya need anything.. because you sure helped me and i thank you...

sounds to me like you have a bad solder joint, or a crossed solder joint. i think pin 9 crossed on me to the trace below it like 3 times and caused my sound to be dead after i modded it.. i had to resolder and clean up the area around pins 7/8/9 on mine after a few mod cycles, but after fixing it, it was fine. make sure none of the solder points from the pins are touching each other from the preamp pins (esp 7/8/9 area) to any of the other preamp board points close by. i had this problem too. if you can't get it, def have someone else do it, cause when i called peavey they told me a new preamp board is 399....so,you dont wanna mess up the traces there by overheating.

the silver mica mod in particular will take care of the fizz without reducing gain...from pins 6/7

i actually put 2 silver micas on a dpdt switch, and one on another switch...switchable in/out (stock).

the bias mod is a must for this amp

 

[Anonymous]

welp...i FINALLY got my 5150 back up and running tonight ...im really happy about this!! about a week ago i went on a stubborn mission of obsession to try and fix it, and i was able to!!!!

it turned out (after much digging around) to be the following:

-two 22ohm flame proof resistors r49 and r47 on the preamp board underneath v4 (pi tube).
after i got those replaced, i got sound back, but it was very faint, very low volume and my high mid low tone knobs had no effect, but presence and resonance worked. i thought it was a cold solder joint or a dead solder joint, but it wasnt, but it was driving me nuts!!!

-so i did some more digging, and someone finally pointed me to the q7 jfet J174 right near the 10ribbon plug in cable coming off the main board to the preamp board.... i removed q7 and it the amp is roaring again! i'll need to replace that jfet though as it is the delay that prevents the popping when switching channels. one of the threads i read referenced a low frequency oscillation and weird ticking and tickling noises and it turned out to be q7. http://music-electronics-forum.com/t10315/ this is the thread that got me on the right track.

gonna throw my mods back in, and 2 new mods someone threw my way (thanks man!), wire it up and fire away!!!!

 

[Anonymous]

Glad to hear the good news!!! Ill have to mark this thread just in case this ever happens to me.

 

[hellaboogie]

Good you got it going, sounds like you learned a lot about the amp

 

[glpg80]

Much congrats! It is near impossible to do bench testing over a forum without having access to the amplifier. Glad you managed to get it up and running

 

[Anonymous]

thanks guys.

a guy on a different forum was able to help me out immensely and without any drama, which i really appreciate.

 

[glpg80]

Yes i remember your PM as well - all i know is what is what i already posted.

I have repaired JFET's before in 5150's simply due to poor soldering practices so it does not surprise me this was one of the problems.

I do know what resistors you speak of on the preamp boards as well - they usually end up blackening the PCB.

 

[Ryan's Guitar Repair]

Big thanks to

Anonymous Guest & Enzo​

Cutting out Q7 JFET B-Channel J174 resurrected the 5150 II that's been on my bench for way to long. I realize this post is old as F^1( but I had to stop and say YEAH ! and Thank You