Smoked My Amp

[Structo]

Dang,
Yesterday I went in to play my 100w ODS clone.
After warm up I turned up the volume a bit and played a couple chords.
The volume went down then it kind of fizzled.

It was then that I noticed that the pilot light was out.
Uh oh.....

A very bad smell was also present.
Because of the smell I was afraid I fired a transformer.

After opening it up and looking around I noticed the relay transformer was super hot.
I looked at the relay power supply board and noticed there was something between the board and chassis. WTF?

It looks like the end of a screw that has been cut off.
I have no idea where it came from or how long it had been there.
It had shorted the bridge rectifier to the chassis, burning the 12v relay transformer.

I always blow out my amps and turn them upside down and tap it on my bench to shake out any debris.

So luckily it wasn't the PT or OT.
I decided to replace all the components in the relay supply to avoid any trouble. Around $20.

I was lucky.

[img:640:512]https://lh5.googleusercontent.com/_MHnI ... rcuit1.jpg[/img]

[img:640:512]https://lh6.googleusercontent.com/_MHnI ... ew_Tip.jpg[/img]

[img:640:512]https://lh4.googleusercontent.com/_MHnI ... Close1.jpg[/img]

Lesson learned?
Always carefully check your amp for bits of metal that can and will short something out. ( I thought I had )

[Colossal]

Good post-mortem Tom. Always good to have a reminder about quality control; you can't be too careful.

[M Fowler]

Do you know where this piece of screw came from?

Good detective work.

[CHIP]

At least you found the cause fairly quickly.

[Structo]

Do you know where this piece of screw came from?

Good detective work.

No that is what is puzzling.

Maybe when I was cutting off a screw it flipped into the open chassis, not sure.

[Firestorm]

You couldn't do it again if you tried.

[talbany]

Tom
Personally I think you just got screwed!!

Tony

[odourboy]

Bad luck! FWIW, I vacuum the inside of my chassis several times during a build and always turn it upside down and shake the hell out of it before powering it up for the first time.

[dcribbs1412]

Wow!
Tom when I read the title of this post I thought the worst...
congrats on the nice troubleshooting
I'm with odourboy...I turn it over and shake it every change I make
man...little things matter
glad it wasn't a bigger/costly issue

[thyx]

Maybe change moniker to DE-Structo?

Seriously, you did get lucky. Murphy must have been asleep that day.

[angelodp]

Well at least it was a low cost deal. Glad you are back up and running.

I have been using forced air and vacuuming at the same time to dislodge any bits.

A

[ER]

You can also add a backer to all the circuit boards, even some thin fish paper will work, you never know. Even if something legitimately fries it will keep arcing from causing collateral damage.

[Structo]

Yeah, a backer board would have prevented it as well as having the board a little further from the wall.
But space is tight there.

It's weird, I do all the same as you, blow out the chassis, shake it, tap it, but some times things might get caught underneath in the wires or something.

I still can't figure out what this thing is.
I would say it is the end of a screw that I cut off with a Dremel but the cut side is concave.

[img:400:317]https://lh6.googleusercontent.com/_MHnI ... oseup2.jpg[/img]

[img:400:320]https://lh3.googleusercontent.com/_MHnI ... oseup1.jpg[/img]

[Zippy]

I still can't figure out what this thing is.
I would say it is the end of a screw that I cut off with a Dremel but the cut side is concave.

Nice photo - looks like it was drilled out.

[groovtubin]

dropped a pc of solder INTO the power tube socket area, ( ya know that darned soldering gun) didn`t see it, powered up, and WATCHED the HEATER resistors go up in FLAMES................it was actually kinda fun to watch! lolol!!

jim@Omega