Holy Crap!!! Smoke

[amiller]

After calculating the bias for my new 5150 III I decided to set on the conservative side. The Weber website bias calculator returns a value of 44mA. The 5150 III will only let me go up to 33mA. So, I set it for 30mA. I remove the Weber biasrite device and put my tubes back in. I turn the amp on, take it off standby, turn up the volume on my guitar and hit a chord...NOTHING. I look over at the amp and see...SMOKE coming from just above the power light. I shut everything off an examined the amp and saw a couple of components that are now BURNT AND BLACK.

CRAP!!!

I guess I'm off to my amp tech to see what the hell happened and get it fixed.

CRAP!!!

 

[cyndicate]

Man sucks to hear that now, I am now scared to bias my own amps

Did you have a load plugged in?

 

[amiller]

Man sucks to hear that now, I am now scared to bias my own amps

Did you have a load plugged in?

I just did the bias on my XTC with no issues...it sounds great now!

Yeah, it makes me afraid to do a bias also...shouldn't be this hard or risky.

 

[FUZZboat]

The 5150 III will only let me go up to 33mA. So, I set it for 30mA. I remove the Weber biasrite device and put my tubes back in. I turn the amp on, take it off standby, turn up the volume on my guitar and hit a chord

stupid question - you had the tubes in the Weber biasrite device when you were setting the bias to 30mA, right ??

 

[amiller]

The 5150 III will only let me go up to 33mA. So, I set it for 30mA. I remove the Weber biasrite device and put my tubes back in. I turn the amp on, take it off standby, turn up the volume on my guitar and hit a chord

stupid question - you had the tubes in the Weber biasrite device when you were setting the bias to 30mA, right ??

Yep, I really don't know how I'd set it without the biasrite. I used the same method I used on the XTC.

 

[FUZZboat]

well since you said that some components are now burnt & black,
I guess that means you had to pull the chassis out of the shell to adjust the bias ??

if so, maybe a connection got shorted to the chassis when re-assembling ?

as cyndicate asked , are you sure the cabinet was indeed connected ? (Fender's are famous for burning up screen resistors in SECONDS when cranked without a load connected !)

which components got burnt, btw ??

I feel your pain - hopefully it was just a screen resistor that got toasted (cheap fix !!)

 

[Loudness250]

If you did what you say you did then it sounds like something that would have happened anyways. Doesnt seem to be anything you did to it that would cause that.

 

[crwnedblasphemy]

Note to self...."Don't purchase amiller's 5150III!"

 

[headlessdeadguy]

Note to self...."Don't purchase amiller's 5150III!"

 

[MrDan666]

which components got burnt, btw ??

If you can post some pics of the burned areas maybe we can help you out a bit quicker too!

 

[meanstreet]

After calculating the bias for my new 5150 III I decided to set on the conservative side. The Weber website bias calculator returns a value of 44mA. The 5150 III will only let me go up to 33mA. So, I set it for 30mA. I remove the Weber biasrite device and put my tubes back in. I turn the amp on, take it off standby, turn up the volume on my guitar and hit a chord...NOTHING. I look over at the amp and see...SMOKE coming from just above the power light. I shut everything off an examined the amp and saw a couple of components that are now BURNT AND BLACK.

CRAP!!!

I guess I'm off to my amp tech to see what the hell happened and get it fixed.

CRAP!!!

Ouch! Who do you use as a tech?

 

[amiller]

After calculating the bias for my new 5150 III I decided to set on the conservative side. The Weber website bias calculator returns a value of 44mA. The 5150 III will only let me go up to 33mA. So, I set it for 30mA. I remove the Weber biasrite device and put my tubes back in. I turn the amp on, take it off standby, turn up the volume on my guitar and hit a chord...NOTHING. I look over at the amp and see...SMOKE coming from just above the power light. I shut everything off an examined the amp and saw a couple of components that are now BURNT AND BLACK.

CRAP!!!

I guess I'm off to my amp tech to see what the hell happened and get it fixed.

CRAP!!!

Ouch! Who do you use as a tech?

Yeah, it really sucks.

The tech is Bob (funny last name ) in Hockessin DE. Do you know of anybody else in DE?

 

[FUZZboat]

Is it still under warranty ??


Put the original tubes back in and return it to where you bought it !

Then Pitch a Bitch

"This is the only the second time I played this amp and all of a sudden ............."

never know , other 5150 III owners may have had similiar failures
and Fender might make it right !!


FWIW

 

[meanstreet]

After calculating the bias for my new 5150 III I decided to set on the conservative side. The Weber website bias calculator returns a value of 44mA. The 5150 III will only let me go up to 33mA. So, I set it for 30mA. I remove the Weber biasrite device and put my tubes back in. I turn the amp on, take it off standby, turn up the volume on my guitar and hit a chord...NOTHING. I look over at the amp and see...SMOKE coming from just above the power light. I shut everything off an examined the amp and saw a couple of components that are now BURNT AND BLACK.

CRAP!!!

I guess I'm off to my amp tech to see what the hell happened and get it fixed.

CRAP!!!

Is that Kanopka (sp?)? If so, he's really the only guy I know. There is a guy up in Ardmore, PA that I used to use also.

Ouch! Who do you use as a tech?

Yeah, it really sucks.

The tech is Bob (funny last name ) in Hockessin DE. Do you know of anybody else in DE?

 

[Jordon]

Talking to Shane at Maken' Music here in Chicago one day, he mentioned that the 5150 III's are having a lot of failure problems. They've had a few just burn out completely randomly in the store. He mentioned smoke and such...could be a similar issue. From what he said, it was a component issue at the factory.

 

[Inearthed]

A guy on the JCF has gone through 3 of them. Assorted failures.

 

[amiller]

The amp tech I use is excellent. I'm going to drop the amp off to him tomorrow. He'll find out what's wrong and most likely the cause. It usually takes a week or two to get an amp back from him...I'll know then if it was me or something inherent in the amp.

 

[Rufus Leaking]

I checked the bias on my 5150 III with the stock Sovteks and it was a very cold 22ma from the factory. Unfortunately the highest I could go with the bias pot was 26ma.

Fender needs to get their shit together with this amp... For $2000 they should be able to make an amp that will bias in range without blowing up.

 

[amiller]

I checked the bias on my 5150 III with the stock Sovteks and it was a very cold 22ma from the factory. Unfortunately the highest I could go with the bias pot was 26ma.

Fender needs to get their shit together with this amp... For $2000 they should be able to make an amp that will bias in range without blowing up.

That's the same issue I had. The bias was set very cold and inconsistent from tube to tube. Also, did you notice a small drop of paint on the edge of the bias adjustment and it's housing. When I turned the bias ajustment the drop of paint broke free for the housing...like breaking a seal. I'm thinking Fender put it there so they could detect if anyone had broken the seal thus invalidating the warranty.

Maybe these amps CAN'T handle a "normal" bias settings and are designed to run cold. Since there's no freaking literature anywhere about the amp (other than very basic user manual) the end user is left in the dark.

 

[FUZZboat]

I checked the bias on my 5150 III with the stock Sovteks and it was a very cold 22ma from the factory. Unfortunately the highest I could go with the bias pot was 26ma.

Fender needs to get their shit together with this amp... For $2000 they should be able to make an amp that will bias in range without blowing up.

That's the same issue I had. The bias was set very cold and inconsistent from tube to tube. Also, did you notice a small drop of paint on the edge of the bias adjustment and it's housing. When I turned the bias ajustment the drop of paint broke free for the housing...like breaking a seal. I'm thinking Fender put it there so they could detect if anyone had broken the seal thus invalidating the warranty.

Maybe these amps CAN'T handle a "normal" bias settings and are designed to run cold. Since there's no freaking literature anywhere about the amp (other than very basic user manual) the end user is left in the dark.

I worked as a Industrial Controlls Test Tech and it was Standard Practice to put finger nail polish on all the trim pots after adjusting them to specs.

SO yeah, the "paint" on the bias pots is put there by a Fender Technician.

AS a far the cold bias, its a simple matter for your tech to change the "setting' resistor/trim pot value in the bias circuit to give a wider range of bias voltage. NOTE: that will most likely VOID THE FENDER WARRANTY !!


"The bias was inconsistent from tube to tube" = if each tube is reading very different current draw then FENDER isn't using matched tubes !! (Cheap Bulk Stock Tubes from China I'll bet !!)