Amp went DC - what to do...?

[boputnam]

Doods...

My son tells me his roomates cranked his system, and fried some or all of his transducers. Reportedly, there was smoke out the ducts. :biting:

So, I have some work to do.

But, tell me you ampheads - is there any risk to continuing to use the amp? It's an Onkyo integrated amp, 100w, not worth much (especially now...). What should be done, if anything?

[Regis]

Depends on what model Onkyo amp it is. If it's an Integra or Grand Integra, it's definitely worth saving as these were TOTL for Onkyo and are well regarded amps. If it's something beyond the usual BPC (Black Plastic Crap) in quality, you might open it up and peer inside, then use your nose to find the first burnt area. Fuses first, then relays then driver boards and finally output tranny's. If it's not too old, tranny's are relatively cheap, depending on obsolesence and package (TO-3, Darlington, etc). Good luck!

[Lancer]

I think SOP is to eBay the whole mess as mint and working perfectly.

- "never mind the fire and smoke, it doesn't affect the sound"

[morbo!]

Doods...

My son tells me his roomates cranked his system, and fried some or all of his transducers. Reportedly

hi bo
i never seen an amp smoke that wanst caused by some1 trying to wire or rewire it while on or tripping over a speaker lead

on the subject of tranducers this is an electrical term for anything that takes an electrical signal and turns it into a real world event i.e a speaker

so i guess that you ment to say the transistors

how much did you pay for it?
u could prolly get a replacment off ebay for the same price as fixing it!
thats unless its a top of the liner in wich case take it to a service techie


p.s i hope him telling you he fryed the tranducers wasnt a fancy way of saying he killed a really nice st of jbl`s you loaned him:mad:

[boputnam]

so i guess that you ment to say the transistors...No, I meant transducers. The speakers in the cabinets got fried (thus the smoke out the ducts). I have no clue what the damage is, but it I can repair / refurbish them.

The amp I have no experience with...

OK. eBay it is! :rotfl:

[Ian Mackenzie]

Bo,

I was wondering if it was the speakers woofer that shorted after bottoming that caused a short and the amp failure? Unless the amp was cooked I find it unlikely the output stage with blow.

I doubt if its worth fixing the amp. You could put a low current fast blow fuse (0.5 amp) in series with the speaker for future potection or even a poly switch which will latch at a certain current current muting the volume until the level is reduced

An alternative that I have not tried but would work in theory is to wire (2) 100 volt 4700 uf electro capacitors wired in series back to back ( + ...- -....+) with the speaker.

This would definately block and Dc current but pass the a/c audio signal. There will be some loss of damping on the woofer but is perhaps an acceptable trade off on another blown woofer.

Ian

[Michael Smith]

Bo
Have you established that the Onkyo amp doesn't go yet?
I've seen cases of speakers getting burnt out and the amp is perfectly OK.
The wake up call is usually when smoke appears cos it's too loud and you have run out of peanut sandwiches and snickers bars BTDT.
Enjoy
Michael

[JuniorJBL]

I doubt if its worth fixing the amp. You could put a low current fast blow fuse (0.5 amp) in series with the speaker for future potection or even a poly switch which will latch at a certain current current muting the volume until the level is reduced

An alternative that I have not tried but would work in theory is to wire (2) 100 volt 4700 uf electro capacitors wired in series back to back ( + ...- -....+) with the speaker.

This would definately block and Dc current but pass the a/c audio signal. There will be some loss of damping on the woofer but is perhaps an acceptable trade off on another blown woofer.

Ian

We use to use light bulbs to keep the dumb @ss's from blowing all their speakers in the car audio world;)

I would try to hook up a cheap speaker to the amp and see what it sounds like, maybe you do not have a problem. one can always hope:hmm:

[morbo!]

OH i understand after 20 cups of coffee

the amp is prolly fine

sell it and buy him a smaller one :D

although clipping isnt good it will probally take him longer to destroy them than with mains power!

[Ian Mackenzie]

We use to use light bulbs to keep the dumb @ss's from blowing all their speakers in the car audio world;)

I would try to hook up a cheap speaker to the amp and see what it sounds like, maybe you do not have a problem. one can always hope:hmm:

Yeah,

Thats an old trick for stage monitor compression drivers too.:thmbsup:

[morbo!]

i take it
thats a 12v globe with a max wattage under the speakers rating?

[Zilch]

http://www.jblpro.com/pub/technote/lowpower.pdf

[morbo!]

as i said i know its not good

but u gotta be really drunk if you cant hear your amp clipping!

[Ken Pachkowsky]

Doods...

Amp went DC - what to do...?

Send him one of those QSC's:applaud:

Ken

[Rolf]

I think SOP is to eBay the whole mess as mint and working perfectly.

- "never mind the fire and smoke, it doesn't affect the sound"

:spin: :spin: :yes: :yes: Right! The buyer will newer know, listening to the mint and silence.:D

Rolf

[Hofmannhp]

Hi Bo,

I would first try to measure the speaker outputs of the amp with a DC Voltmeter, without connected speakers (but pls set a dummy load of some >100 Ohms/5Watts).
With a 100W amp I think that the power supply works with +- 40VDC min.
If there's a meter sign of +40 or - 40 that's mostly a defect in the last amp stage (the power trannys) or the driver stage before the power stage. I don't know the technical design of this amp (if it's assembled with discrete semiconductors or integrated parts). When the DC measurement shows a high output voltage, try to unsolder the (mostly complementary) driver stage and the power trannys and measure their function. When you find out that there's a smoked part, you got it. Also a posibility are burned power resistors in the output bridge stage (resistors with about 0.3 to 0.8 Ohms)

HP

PS: questions....PM me