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Double Bass SWR blowout? fuse? i need some help

M

macdeezy

Jan 17, 2010
26
2
Reno, Nevada
www.facebook.com
#1
My SWR working man's 12 stopped working in the middle of a gig last week!

It squealed and popped and wouldn't turn back on. :(

I'm not sure what the problem is but maybe you folks can help me out.

Some background:
I have been playing on this amp for 10 yrs+ and it has always been good to me. I've used it for guitar, electric bass and most recently upright bass (two years). The amp had previous work done on it (capacitors and tweeter) about 3 years ago.

I've been running upright through it with a K&K and it has worked pretty well for me. Never having to crank it too loud...utilizing the DI whenever necessary.

So anyways, I'm not sure what to do here...has anyone had any problems with amps crapping out with a squeal and pop?

Thanks,
Mac
 
#2
It's certainly something in the electronics.

Take it to a repair shop or contact SWR directly at

Invalid Link Removed

Go to Support and click service centers for your closest authorised shop.

Either way, if you can't walk in and hand the repair to them, you'll pay shipping both ways plus the cost of the repair.

It may be more benificial to just go out and buy something new only because it's not a small fortune to replace, and if you've used it for 10 years, you've got your money out of it by now.

Hope this helped. good luck!
 
#4
Hi.

+1 for contacting Fender (SWR), they may help US customers, even though the same doesn't go for us Europeans





The following is only based on the WM10, so it may or may not apply to WM12 if the circuit topology isn't the same.

The first batch of the hybrid chip (if there's one) was really bad, the upgrades were better. The chip ~$10 was the only part mine (WM10) needed.

Regards
Sam
 
#5
macdeezy said:
My SWR working man's 12 stopped working in the middle of a gig last week!

It squealed and popped and wouldn't turn back on. :(

I'm not sure what the problem is but maybe you folks can help me out.


So anyways, I'm not sure what to do here...has anyone had any problems with amps crapping out with a squeal and pop?

Thanks,
Mac
Click to expand...

Mac,
First, check the external fuse and see if it's blown. If it is then you'll want to replace it, with a new one of the same amperage ( not a slow blow) . If that doesn't fix it then try to get to the inside of the amp itself and see if there is another fuse on the circuit board. I'm fairly certain that SWR's have one there as well.


Ric
 
#6
Take care when you open any amp. There can be enough voltage in a capacitor to kill you even when the amp is off and unplugged. Changing an internal fuse should be fine but you should still be careful.
 
#8
macdeezy said:
My SWR working man's 12 stopped working in the middle of a gig last week!

It squealed and popped and wouldn't turn back on. :(

I'm not sure what the problem is but maybe you folks can help me out.

So anyways, I'm not sure what to do here...has anyone had any problems with amps crapping out with a squeal and pop?

Thanks,
Mac
Click to expand...

Mac,
I located the schematics for a Workingman's 12 perhaps someone here on TB is fluent enough to determine whether there is a fuse or not. I'm not technically proficient enough to read one for a solid state device.
 

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#9
It’s the squeal that worries me. The pop could be when the fuse went. I wouldn’t be expecting a new fuse to help. By all means try it but you should be finding a tech. It may or may not be a major fault, you just cannot tell at this stage. I would guess a blown component.

+1 be very careful opening an amp, there are latent voltages inside even when unpowered.

Good luck
 
#10
Rastus_01 said:
It’s the squeal that worries me. The pop could be when the fuse went. I wouldn’t be expecting a new fuse to help. By all means try it but you should be finding a tech. It may or may not be a major fault, you just cannot tell at this stage. I would guess a blown component.

+1 be very careful opening an amp, there are latent voltages inside even when unpowered.

Good luck
Click to expand...

Rastus,
I took a look at the users manual and you are absolutely correct about the possibility of a failure with something inside the amp. Seems the fuse can blow under two different conditions. Here's the info from the SWR users manual for the Workingman's 12.

"A/C LINE FUSE"

"The line fuse can open (blow) due to power surges or high powerline transients. This fuse will also open in the event of an electronics failure inside your amplifier. "

"Correct size and rating of the Line (Mains) fuse: 3AG, 3 amp slo-blow for 120V operation (North America), and 1 1/2 amp slo-blo for 240V operation."

One thing here however, I was advised never to use a slow-blow fuse in any of my amps as you could fry the circuit board before the fuse blew. Just my take.

Ric
 
#11
There are probably two fuses. The schematic shows a fuse inline with the speaker output, second page, all the way to the right. It doesn't show the power transformer and mains input, which are where the mains fuse would be.

If the output fuse is blown, chances are it saved your speaker from being damaged by something going wrong with the amp. In that case, one might want to be sure that the amp is functioning before replacing the fuse. Measuring the DC output would be prudent.
 
#12
Thanks to a nice PM from Ric, I'd like to comment on slow versus fast blow fuses. Some designs might use a slow blow fuse if the load has a turn-on surge. But that should be up to the designer, and you should always replace a fuse with the exact same type. Doing otherwise is a form of "shooting the messenger."

Normally, fuses shouldn't blow. Most designers don't consider fuse replacement to be a normal user maintenance activity. Something is probably wrong with the amp.
 

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