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Solid State Amplifiers => Amplifier Discussion => Topic started by: Megabunny on May 04, 2011, 10:42:05 AM

Title: Zoom 15watt Modeling Amp BUZZES
Post by: Megabunny on May 04, 2011, 10:42:05 AM
My 15Watt ZOOM SS Amp makes this god awful Buzzing http://www.youtube.com/watch?v=a90r9CmQ8Eg (http://www.youtube.com/watch?v=a90r9CmQ8Eg)

no matter what i do it wont make ANY other noise. not louder not quieter. guitar input make no difference either.

any ideas?

TY guys
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on May 04, 2011, 11:44:26 AM
Sounds like when I had a SansAmp with a blown TDA2050 power amp chip.  It also had two burned out rectification diodes.  I'd say open her up, odds are you have some burn marks on your pcb.  Even if you don't we can help you sort out what's going on.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: mensur on May 04, 2011, 01:14:01 PM
It's blown amp, you have to replace the whole power section.That buzz you hear is DC voltage, and it can fry your speakers.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on May 04, 2011, 03:48:16 PM
Quote from: mensur on May 04, 2011, 01:14:01 PM
It's blown amp, you have to replace the whole power section.That buzz you hear is DC voltage, and it can fry your speakers.

You say "whole power section", but that should just be a single chip since most cheap amps use an IC for their power amp section.  Should be a TDA2030, LM1875 or similar.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: mensur on May 04, 2011, 06:01:22 PM
Quote from: joecool85 on May 04, 2011, 03:48:16 PM
Quote from: mensur on May 04, 2011, 01:14:01 PM
It's blown amp, you have to replace the whole power section.That buzz you hear is DC voltage, and it can fry your speakers.

You say "whole power section", but that should just be a single chip since most cheap amps use an IC for their power amp section.  Should be a TDA2030, LM1875 or similar.
I know it's a chip amp, but maybe there are faulty caps, resistors, again it's only few components.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on May 05, 2011, 09:32:15 AM
Quote from: mensur on May 04, 2011, 06:01:22 PM
I know it's a chip amp, but maybe there are faulty caps, resistors, again it's only few components.

Yes, it is possible in theory that there couple a bad cap or resistor somewhere as well.  I've not seen it happen though.  It seems the IC always goes well before taking out any of the discrete components.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: Megabunny on May 06, 2011, 10:59:46 AM
is this the chip your talking about?


"http://a6.sphotos.ak.fbcdn.net/hphotos-ak-snc6/224254_10150174223567043_722767042_7004812_7465298_n.jpg"
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: teemuk on May 06, 2011, 11:30:10 AM
^ Yes.

Definitely sounds like blown output chip. Don't keep the faulty amp on like that too long, it'll toast the speaker in no time. Then the $1 repair turns to a ~ $50 - $80 repair.

Repair of this stuff is indeed often as easy as throwing in a replacement chip. I'd still momentarily unplug the speaker and (after the repair) measure that no DC voltage potential exists in between the speaker leads just to be on the safe side.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on May 06, 2011, 01:34:34 PM
Yeah, that's the one.  Replace that baby and away you go!  (Probably).  Every now and then it might take something else with it, but it's unlikely.  Just buy two of whatever that IC is, they should be cheap anyway.  That way if you blow the first one you can figure out why then install the second one.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: DartPlayer170 on May 06, 2011, 02:52:46 PM
It's also a good idea to buy some heat sink compound and re-apply to the new IC. Clean the old guck off the heat sink first. This will help prevent the new IC from burning out quickly.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: Megabunny on May 10, 2011, 08:46:29 AM
Kk here's the update.

Ordered 5 x TDA2030a
Took the old one ff to double chck part numbers and the thermal paste still has the foil on the inside, so its wasn't properly applied when it was made.

Gonna fit new TDA2030a then post update.

Thanks guys... much love.


Mike.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on May 10, 2011, 10:12:19 AM
Quote from: Megabunny on May 10, 2011, 08:46:29 AM
Kk here's the update.

Ordered 5 x TDA2030a
Took the old one ff to double chck part numbers and the thermal paste still has the foil on the inside, so its wasn't properly applied when it was made.

Gonna fit new TDA2030a then post update.

Thanks guys... much love.


Mike.

What do you mean "still has the foil on the inside"?
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: Megabunny on May 10, 2011, 05:16:17 PM
The chip comes pre packed with a little bit of thermal paste. You peel off the foil and stick it to the heat sink,

cheap computer processors usually come with it.

So I peeled it off and the thermal paste was still fresh. The guy who built it in the factory must have forgotten to take it off before screwing it together.

The TDA2030a chip is visibly burnt so I'm still going to replace it. Then I'll Update you guys, parts are coming from Hong Kong so it may be as much as 20 days before I reply again. Unless you guys have any question's.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on May 11, 2011, 06:33:01 AM
Quote from: Megabunny on May 10, 2011, 05:16:17 PM
The chip comes pre packed with a little bit of thermal paste. You peel off the foil and stick it to the heat sink,

cheap computer processors usually come with it.

So I peeled it off and the thermal paste was still fresh. The guy who built it in the factory must have forgotten to take it off before screwing it together.

The TDA2030a chip is visibly burnt so I'm still going to replace it. Then I'll Update you guys, parts are coming from Hong Kong so it may be as much as 20 days before I reply again. Unless you guys have any question's.

Weird, I've not ever seen that.  Sounds like that might be why you had problems.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: teemuk on May 11, 2011, 07:00:44 AM
Are you sure it was the foil and not the electric insulator that you need between the chip and the heatsink?

Whenever I have bought those chips from a local "radioshack" wannabe store they have always lacked a peelable foil and pre-applied thermal paste.  ???
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: Megabunny on May 17, 2011, 03:51:19 PM
Just to confirm.
The foil on the back of TDA2030 was still intact. I contacted Zoom and I was given an apology and £15 off my next zoom purchase. Several of The amps made around the same time as mine had similar faults. Xbox 360s get it all the time.

Will update when tda2030 arrive.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: J M Fahey on May 18, 2011, 06:08:32 AM
Quotean apology and £15 off my next zoom purchase.
Make that  £10 cash and we are even  :lmao:
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: Megabunny on May 18, 2011, 04:07:58 PM
Quote from: J M Fahey on May 18, 2011, 06:08:32 AM
Quotean apology and £15 off my next zoom purchase.
Make that  £10 cash and we are even  :lmao:
s
lol
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on May 18, 2011, 04:18:42 PM
Wow, that's really strange.  At least they are owning up to it and giving you a bit of credit on a future purchase.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: Megabunny on May 23, 2011, 01:54:44 PM
Tda2030a fitted.
Buzzing remains.
Any thoughts, dry pots are my next idea.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: phatt on May 24, 2011, 08:43:21 AM
As is often the case the issue probably damaged more than just the chip.


Tell em to keep the $15 and send a new whole new rig :trouble
Phil.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on May 24, 2011, 09:58:26 AM
Quote from: phatt on May 24, 2011, 08:43:21 AM
As is often the case the issue probably damaged more than just the chip.


Tell em to keep the $15 and send a new whole new rig :trouble
Phil.

Given the situation, I agree.  However, it should still be repairable it will just take more work.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: teemuk on May 24, 2011, 03:16:41 PM
Next rather obvious reason for severe hum would be faulty filter caps or regulator circuits.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: Megabunny on May 27, 2011, 07:18:28 AM
Okay, so at this point I'm thinking maybe I'll pay a specialist to fix this, the tda was fun and simple but anything above pots and I'm not the most eager to be poking around.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on May 27, 2011, 08:03:15 AM
Quote from: Megabunny on May 27, 2011, 07:18:28 AM
Okay, so at this point I'm thinking maybe I'll pay a specialist to fix this, the tda was fun and simple but anything above pots and I'm not the most eager to be poking around.

Capacitors are an easy replacement and really the rest of the circuit shouldn't be much more difficult than what you did replacing the tda.  Unless of course it had something to do with the modeling circuitry - which is unlikely.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: Megabunny on June 03, 2011, 10:39:06 AM
i cant see any other damage. i can take more pictures for you guys if you like, i you think its repairable then i'll give it a go.
Title: Re: Zoom 15watt Modeling Amp BUZZES
Post by: joecool85 on June 03, 2011, 11:10:14 AM
Quote from: Megabunny on June 03, 2011, 10:39:06 AM
i cant see any other damage. i can take more pictures for you guys if you like, i you think its repairable then i'll give it a go.

You likely won't see any more damage, but you would rather have to start testing for it with a voltmeter etc.