# USX 2150 (blue bar) - how's this look?



## mdcruz88 (Dec 24, 2010)

Sup guys,

I bought a USX-2150 (blue bar variant made in Korea) from AudioClinic and got it in the mail today. I know it's not "Zed made", but I'm only using it for sub duty.

Anyways, I popped the backplate to take a gander at the guts and saw where he might have made repairs. 

I have no idea what I'm looking at, so I was hoping somebody could tell me if it looks good or bad. Some of the resistors (I think?) look burnt along with their connectors? 

I haven't fired it up yet as I don't have anything to connect it to as yet. Still in the system buildup process. 

------

Board stamp and burnt stuffs (I love how it says "engineered" in the US)










Close up Shot...looks to be soldered on, but it's crooked??










Top Cover










Made in Korea











What you guys say? 

--===mike d


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## envisionelec (Dec 14, 2005)

mdcruz88 said:


> Sup guys,
> 
> I bought a USX-2150 (blue bar variant made in Korea) from AudioClinic and got it in the mail today. I know it's not "Zed made", but I'm only using it for sub duty.
> 
> ...


It's blown. Did you think you were buying a working amp!?

Needs at least half the bank of FETs replaced along with the gate stopper resistors. 

This series is about as good as the old Profile California series - also in about 80% of the late 90's era amplifiers. Just meh.


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## mdcruz88 (Dec 24, 2010)

Damn for real? Yes I bought this thinking it was a working unit. 

About to send an email to the guy to see wsup. Are you sure that's just not a sloppy repair job?


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## envisionelec (Dec 14, 2005)

mdcruz88 said:


> Damn for real? Yes I bought this thinking it was a working unit.
> 
> About to send an email to the guy to see wsup. Are you sure that's just not a sloppy repair job?


Q8 and R36 are decimated.

And yes, I'm sure.

It actually might work - but it will fail catastrophically if you don't get this part fixed immediately.


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## mdcruz88 (Dec 24, 2010)

envisionelec said:


> Q8 and R36 are decimated.
> 
> And yes, I'm sure.
> 
> It actually might work - but it will fail catastrophically if you don't get this part fixed immediately.


Envisionelec, thanks tons man!!!!!!!!!!!!!!!  If you didn't comment on the thread I would have never known.

I emailed AudioClinic and this was his response:

------------------
I would agree that it looks like a problem. I do check each amp just prior to
shipping and am certain it was functional. I apologize for the inconvenience. 
Please return the amp for repair or full refund at your convenience.
------------------

Needless to say, I'm shipping this POS back to him and getting a refund.

Anybody have a 2-channel or mono amp that'll do 300+ at 4ohm? LOL


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## Cheveyboy (Dec 25, 2010)

Oh man, was just going to buy a USX 2080 from him.

Now I'm having doubts.

Are you swaping for another, repair, or money back?


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## mdcruz88 (Dec 24, 2010)

I think you should be alright. As with any used purchase always inspect/test as soon as possible. 

I think in this instance he tested the unit as fine and assumed all was well with the unit. Not the best practice in the world, but my guess is that he was playing the odds.

The good thing is that he's really responsive and offers a 30 day return/refund window. As such, I decided to give him the benefit of the doubt and go for a repair. I'll report back how the unit is once I get it back.


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## Cheveyboy (Dec 25, 2010)

Thanks man.

My only concern is that I wont be installing it for some time, and have no way of bench testing it. 

I guess I can pop it open and give it a visiual. But thats only going to tell so much without given the beans to it.


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## mdcruz88 (Dec 24, 2010)

Update:

I got a tracking number from him yesterday and it shows that shipment is in the "initiated stage". It seems it's been like that since Monday, May 2nd as that's when it states the info was sent to FedEx.

Hoping that this will move onto the "picked up" stage soon.


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## Kane (Mar 3, 2009)

i have a crossfire vr302 that will do 300+ that i would possibly let go.


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## mdcruz88 (Dec 24, 2010)

Kane said:


> i have a crossfire vr302 that will do 300+ that i would possibly let go.


I appreciate the offer and will keep it in mind just in case.


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## mdcruz88 (Dec 24, 2010)

Alright, go the amp back.

So far I'd say it looks good. Ya?


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## envisionelec (Dec 14, 2005)

The repair was done. I can't speak for the rest of the amp.

My eye spies that it has a regulated power supply. I would expect it to be murder on those already-bulging secondary side filter caps.
I don't understand amp shops that don't notice this stuff. Makes me want to get back in the game...


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## wannabesq (Apr 13, 2011)

I bought a 2150 from the same guy at around the same time and it was fine. I believe he still has one or two on ebay. I bought from him because he guaranteed the work for 30 days, and the option to repair or full refund. So far so good. I have had at least 2 of this exact amp fail before, so I don't have high hopes, but it was cheap and fits the bill for the time being.


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## Doyle Hargrave (Dec 21, 2009)

I just caught this post on a google search:

US Acoustics 2150 test results - Club Lexus Forums

Any thoughts? I was about to buy one of these myself to push some RK6's. If there is some truth to it, do you have a lesser known brand that you like? I'd rather buy quality than a name.


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## envisionelec (Dec 14, 2005)

Doyle Hargrave said:


> I just caught this post on a google search:
> 
> US Acoustics 2150 test results - Club Lexus Forums
> 
> Any thoughts? I was about to buy one of these myself to push some RK6's. If there is some truth to it, do you have a lesser known brand that you like? I'd rather buy quality than a name.


There is no merit to an unqualified test. And that post is from 2003.

A) What is the correct model number? Zed built the medium grey ones and the first gen "wide heatsink" USX versions. If it has a blue LED bar - it's not Zed. 
B) Let's see real numbers / waveforms. Conjecture means nothing.
C) What is the test equipment? Are the practitioners experienced in testing car amplifiers?

Lots of holes - I'm not surprised they got flamed.


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## mdcruz88 (Dec 24, 2010)

wannabesq said:


> I bought a 2150 from the same guy at around the same time and it was fine. I believe he still has one or two on ebay. I bought from him because he guaranteed the work for 30 days, and the option to repair or full refund. So far so good. I have had at least 2 of this exact amp fail before, so I don't have high hopes, but it was cheap and fits the bill for the time being.


We most likely got it from the same source. He has a ton of USX's on auction all the time.

I bought the amp for the exact same reasons you did. It's cheap, supposedly decent power, 30 day repair/refund and fits my build.

On a side note, I'm waiting on DAT to pick up some of those new 4 channel PPI Phantoms to try out!


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## mdcruz88 (Dec 24, 2010)

envisionelec said:


> There is no merit to an unqualified test. And that post is from 2003.
> 
> A) What is the correct model number? Zed built the medium grey ones and the first gen "wide heatsink" USX versions. If it has a blue LED bar - it's not Zed.
> B) Let's see real numbers / waveforms. Conjecture means nothing.
> ...


I've got two USX-4065's. One with the blue bar and one without. 

I was going to open them up and do a comparo, but I can't seem to figure out how to get the cover off the non-blue bar one. There's no screws holding the cover, but rather it looks like it slides on and off between guard rails? Sure is on there pretty tight...


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## envisionelec (Dec 14, 2005)

mdcruz88 said:


> I've got two USX-4065's. One with the blue bar and one without.
> 
> I was going to open them up and do a comparo, but I can't seem to figure out how to get the cover off the non-blue bar one. There's no screws holding the cover, but rather it looks like it slides on and off between guard rails? Sure is on there pretty tight...


It _is_ tight. Wear some gloves - I cut the living shhh out of my hand pulling one off back in the day.

On first glance, the differences appear small. 

There are some things to keep in mind with the Korean (and now Chinese) amps. Their magnetics are often horrible - easily saturated which blows power supply MosFets and generally limits current prematurely. 

Second is the extensive use of wire jumpers which increases resistance by forcing large current through a tiny solder connection. To make matters worse, these "punched" cheap paper CEM boards from Korea always have enormous component drill holes making cold and cracked solder connections common.

I wouldn't install them because I don't like constantly servicing an installation.


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