# Input stage failing on Alpine 3553?



## AcquaCow (Nov 7, 2007)

I've got a near-mint Alpine 3553 from the 90s era, but channel 1 is flaking on me 

It refuses to work at low volume and the only way to get it to start working is to turn the input volume up to about 75%. Sound will immediately start to come out on the lower frequency ranges, but will be very scratchy at first, then after a few seconds, the full spectrum will be played and the amp will seem normal. I can turn the volume back down, but after a little while, channel 1 will cut out again 

I'm handy with a soldering iron and a multimeter, I've done plenty of digital circuitry troubleshooting, but analog stuff is pretty new to me.

Anything I should look for when I crack this open?

Anyone else want to crack this open?

Thanks,

-- Dave


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## Hillbilly SQ (Jan 26, 2007)

check and make sure the speaker for channel 1 isn't mostly blown first. i've seen partially blown speakers do just what you described.


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## AcquaCow (Nov 7, 2007)

TEAM SHIMANO/FALCON said:


> check and make sure the speaker for channel 1 isn't mostly blown first. i've seen partially blown speakers do just what you described.


The speaker isn't blown. The problem is definitely with the amp.

This is the second car the amp has done this in as well. I thought it was just an install issue with the old car, but apparently not.

-- Dave


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## chad (Jun 30, 2005)

Pull all the connections from ribbons, multi pin connections, etc. Clean them with de-oxit, re-seat them a few times and see where that leaves you.

Oxidation is usually the root cause of having to "blow it open"

Chad


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## AcquaCow (Nov 7, 2007)

I snapped a pic of it.

Click the image for the *FULL* ~2.8mb image if you want a real look around.

CH1 is labeled where the orange wire hits the board.



-- Dave


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## AcquaCow (Nov 7, 2007)

Hmm, I apparently need 5 posts before I can post any images...


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## AcquaCow (Nov 7, 2007)

I just took a large closeup @ 10mp and will upload it now.

-- Dave


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## AcquaCow (Nov 7, 2007)

Alright, pic is hosted with a smaller version that you can click through to the large one...

Click the image below for the *FULL ~2.5mb* closeup.

Channel 1 is where the *orange* wire hits the board.




Thanks,

-- Dave


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## chad (Jun 30, 2005)

All those white plugs... Clean them up and re-seat them a few times, Check the integrity of the solder ont he input jacks and pots, cleant he pots too. If you still have issues you may have to pull the board and look for cold joints elsewhere.

How do you do that copyright marking?

Chad


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## envisionelec (Dec 14, 2005)

chad said:


> All those white plugs... Clean them up and re-seat them a few times, Check the integrity of the solder ont he input jacks and pots, cleant he pots too. If you still have issues you may have to pull the board and look for cold joints elsewhere.
> 
> How do you do that copyright marking?
> 
> Chad



All those white plugs (with the exception of two signal input connectors) are directly soldered to the board. 

This amp has output driver ICs which routinely die in the exact manner that the poster describes. IC106 is what I'm talking about: the metal-tabbed chip just about 1/2" to the left of the orange wire. I don't remember the part number, but I think it was an NEC device. µPC1225, maybe? If so, audiolabga.com carries them.


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## chad (Jun 30, 2005)

ezaudio said:


> All those white plugs (with the exception of two signal input connectors) are directly soldered to the board.


I spy more than that  Is the daughter board directly soldered too or removable?

Why shotgun out components before you rule out the obvious? Like you I have had my share of time on the bench.


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## envisionelec (Dec 14, 2005)

chad said:


> I spy more than that  Is the daughter board directly soldered too or removable?
> 
> Why shotgun out components before you rule out the obvious? Like you I have had my share of time on the bench.


Ok, related to audio. What would the connector for the front panel bi-color LED have to do with his problems?

It's soldered in.

Why shotgun out components at all? What is more obvious than what I just described? 

I don't know if you're like me at all. I don't spend time playing with things that won't fix the problem, or even narrow it down. I get in and get out. Alpine didn't have a major problem with solder connections during the years this amp was made. This is why I'm not saying "Go solder all these connections" like I would if it was a Pioneer GMX series amp (emitter resistors).


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## chad (Jun 30, 2005)

ezaudio said:


> like I would if it was a Pioneer GMX series amp (emitter resistors).


[shudders]

Very well then.

Ever do much pro audio/MI stuff? I was going to bring up another grrrrrrr thing that chaps the ass 

Chad


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## AcquaCow (Nov 7, 2007)

ezaudio said:


> All those white plugs (with the exception of two signal input connectors) are directly soldered to the board.


That would explain why I can't seem to unplug them =)



ezaudio said:


> This amp has output driver ICs which routinely die in the exact manner that the poster describes. IC106 is what I'm talking about: the metal-tabbed chip just about 1/2" to the left of the orange wire. I don't remember the part number, but I think it was an NEC device. µPC1225, maybe? If so, audiolabga.com carries them.


 I'll look into this and verify whatever is printed on the chip tomorrow...

Thanks,

-- Dave


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## AcquaCow (Nov 7, 2007)

chad said:


> How do you do that copyright marking?
> 
> Chad


It's an action script I created for photoshop.

-- Dave


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## chad (Jun 30, 2005)

AcquaCow said:


> It's an action script I created for photoshop.
> 
> -- Dave


Thanks, I'm not pic savvy enough to use photoshop unfortunately  

I've seen a few of my pics pop up elsewhere, and sometimes that does not make me so happy.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

Dam Dave, that didn't take very long... 

I would consider solder as well, now that I think about it... When I was doing HU repairs 65% of what I did was bad solder... I would just hit most all of the solder joints and many times it worked... 

ezaudio is the man when it comes down to repairs though bro, lets see, out of the 5 SS Reference amps he bought off me, he had 4 of them running again in under 3hrs...!!!!! 

Chads got it goin on in the troubleshooting Dept. as well, there are many things to be learned from these guys, I know, in the 3 weeks i've been here, i've learned quite a bit... 

Cheers


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## envisionelec (Dec 14, 2005)

Aaron'z 2.5RS/WRX said:


> Dam Dave, that didn't take very long...
> 
> I would consider solder as well, now that I think about it... When I was doing HU repairs 65% of what I did was bad solder... I would just hit most all of the solder joints and many times it worked...
> 
> ...


I would have had all working, but I needed to buy the Volt/Current switch, which I didn't have on hand. But yeah...3 hours including cleaning between all the fins and in the terminal blocks. 

Lemme say that car amps of a certain type exhibit similar failure modes. If you connect Power and GND and a huge amount of current is drawn _immediately_, then you have a switching FET or reverse blocking diode short. If you get to the turn-on point and current draw shoots up quickly, you have an output stage short. On one of the amps, I was seeing current rise higher and higher - I immediately suspected a leaky rectifier. The reason was that I was seeing a big shift in rail voltage. One rail was at +42V and the other was -3.4V. Since rectifier failures are super common for Soundstream amps, I didn't sink a bunch of time into other possibilities.

The breakdown of the repairs was: 

*Amp 1)* TIP102/107 transistor replacement. 
*Amp 2)* Burnt 10 ohm signal/speaker ground isolation resistor
*Amp 3)* Blown rectifier diode and Burnt High Voltage/High Current switch
*Amp 4)* TIP102/107 transistor replacement.
*Amp 5)* Parts donor till replacements come in. The chassis was nekkid, so not worth fixing right away.


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## envisionelec (Dec 14, 2005)

chad said:


> [shudders]
> 
> Very well then.
> 
> ...


Thanks for not taking that badly. I re-read it later and found it to be a bit terse. So...sorry.

I don't do _much_ Pro audio; maybe two or three times per year. Usually amps and mixers...

Bring it on. If I don't have the answer, I'll say so. I won't BS you.


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## AcquaCow (Nov 7, 2007)

AcquaCow said:


> That would explain why I can't seem to unplug them =)
> 
> I'll look into this and verify whatever is printed on the chip tomorrow...
> 
> ...


NEC µPC1270h
9135E

I guess I should replace all 4, no?

audiolabga.com has 2 in stock...

Is there a recommended replacement that is better and won't fail like this? My 3555's never had this issue...

Thanks,

-- Dave


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## chad (Jun 30, 2005)

ezaudio said:


> Thanks for not taking that badly. I re-read it later and found it to be a bit terse. So...sorry.
> 
> I don't do _much_ Pro audio; maybe two or three times per year. Usually amps and mixers...
> 
> Bring it on. If I don't have the answer, I'll say so. I won't BS you.


No reason to take it bad, look man, we are both techs, and I KNOW the tech "Jesus you gotta be kidding me" mentality  We all exhibit it  

I don't have the experience in car audio repair that you do and will fully admit it, hell, at first I thought he was talking about a head unit :blush: 

We just work in different worlds of audio, and that's a good thing, the more different worlds the merrier here!

What DID happen is that it proved to others that electronics repair is 30% knowledge, 70% EXPERIENCE, and 10% voodoo. And it takes all 110% at times  You can have all the electronics knowledge in the world but that does not make you good on the bench, the experience is passed down thru generations of techs IMHO. then after the initial "oh that's why" the individual develops their own way of working, evolving the quirky, sometime lovably nerdy crowd we know as bench techs 

Chad


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## durwood (Mar 7, 2007)

ezaudio said:


> I would have had all working, but I needed to buy the Volt/Current switch, which I didn't have on hand. But yeah...3 hours including cleaning between all the fins and in the terminal blocks.


If you still need a source on those switches I've got a few I bought a while back. Let me know.


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## envisionelec (Dec 14, 2005)

durwood said:


> If you still need a source on those switches I've got a few I bought a while back. Let me know.


Yeah, why not? PM me with the details.


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## envisionelec (Dec 14, 2005)

chad said:


> No reason to take it bad, look man, we are both techs, and I KNOW the tech "Jesus you gotta be kidding me" mentality  We all exhibit it


 


chad said:


> I don't have the experience in car audio repair that you do and will fully admit it, hell, at first I thought he was talking about a head unit :blush:
> 
> We just work in different worlds of audio, and that's a good thing, the more different worlds the merrier here!


Yeah, you don't see me on the ProSoundWeb forums talking about fixing their amplifiers. While I can repair what is in front of me - no problem - I don't have that "instinct" to know what particular problems a brand or model might have.



chad said:


> What DID happen is that it proved to others that electronics repair is 30% knowledge, 70% EXPERIENCE, and 10% voodoo. And it takes all 110% at times  You can have all the electronics knowledge in the world but that does not make you good on the bench, the experience is passed down thru generations of techs IMHO. then after the initial "oh that's why" the individual develops their own way of working, evolving the quirky, sometime lovably nerdy crowd we know as bench techs
> 
> Chad


Yes, hell yes. Nerd. Geek. I embrace them both. Except I'm not a gamer nor do I read sci-fi books. 

Longish story ahead...

A little history of my experiences.. I worked for a guy, "Dave", that ran an Alpine/Sony/Delco warranty repair station in my home state. I was going to school at the time I worked there and was trying to get my foot in the technician door to escape installer duties. Besides, the tech room was A/C and the install bays were not.... 

I had been repairing VCRs (this was the late 80's, kids) in junior-high and high school. I moved on to car audio since it really challenged me more than any home audio could. I had to learn switchmode power supplies. I bought a RadioShack schematic for one of their 170W amps...a Pyramid SuperBlue in disguise. I poured over that thing, taking in all the details and memorizing part numbers. After taking in and repairing a dozen or so amps that fairly resembled that one schematic, I was pretty confident in my skillz and decided to pursue the car audio repair business - but I had to start as an installer.

Back to the bays. During one exceptionally backed-up day, one of the installers reversed polarity to the customer's Rockford amp. Of course, this blew the fuse, but it also took out one of the MosFets since RF doesn't (or didn't) use reverse blocking diodes. The boss was a bit concerned until I volunteered to repair it. "No, send it back to Dave so he can fix it today." Well, Dave was the type of guy that didn't like interruption. He naturally refused to do the repair. So the boss looks at me and says " If you can do it...go for it, BUT DON'T BREAK IT!" A half hour later, we installed the amp and the customer was happy. We were the type of shop to tell the customer what happened and he was OK with it (I wouldn't have been!), so it was all good. But, boy, that pi$$ed Dave off. From then I edged into amplifier repair and was soon doing all the amps the shop brought in. I was probably doing 3-4 per day since our new Yellow Pages ad specifically touted car amplifier repair. 

So...my experience is pretty good. And not just "shoot and swap" either. I don't reheat solder connections for the hell of it and I don't replace parts that probably won't get me any further along. Yes, there are dogs out there that kick your ass six ways from Sunday, but once you learn them you never forget.

Oh, and I've built my own, too. It's not hard!!


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## AcquaCow (Nov 7, 2007)

AcquaCow said:


> NEC µPC1270h
> 9135E
> 
> I guess I should replace all 4, no?
> ...


Yes? No?

Thanks,

-- Dave


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## chad (Jun 30, 2005)

ezaudio said:


> Yes, hell yes. Nerd. Geek. I embrace them both. Except I'm not a gamer nor do I read sci-fi books.


Same here! 



ezaudio said:


> So...my experience is pretty good. And not just "shoot and swap" either. I don't reheat solder connections for the hell of it and I don't replace parts that probably won't get me any further along. Yes, there are dogs out there that kick your ass six ways from Sunday, but once you learn them you never forget.


I don't shotgun unless experience says that it's a good idea. For example 2N5551's and 5401's that make up the sense for the protection comparator in crest amps. Under certain conditions after a final failure they can get leaky, just fine on the bench at 120V but ramp it up to 125 or throw the voltage around as in a real world situation and you have trouble on the horizon.

I do re-flow work on notorious issues also, I got thru all ins and outs, if it looks lacking from the original flow it gets hit again, again it's like the pioneer emitter resistor thing, sometimes it's just not a bad idea to check or just re do for good measure. I won't dig in to do it but while it's in front of me......

Like we both agree, it's experience, unfortunately in my world a failure can cost the end user money big time. I can assure you there are QSC RMX2450's with original rail commutating FET's working just fine. But if one comes in for something else, they are getting replaced as per my experience even BEFORE QSC put out a tech bulletin. Little things, you know.



ezaudio said:


> Oh, and I've built my own, too. It's not hard!!


I've done a couple SS amps, I build a couple tube amps per winter, I just dig working on them for some reason. I also restore antique radios, you know, a stray from the norm, I find peace in it.

Chad


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## envisionelec (Dec 14, 2005)

AcquaCow said:


> Yes? No?
> 
> Thanks,
> 
> -- Dave


I wouldn't replace all of them. Save yourself some time and chalk it up to a bad die bond or something.

EDIT: Sorry for ignoring you, Dave. I got a little carried away.


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## envisionelec (Dec 14, 2005)

chad said:


> Same here!
> 
> 
> 
> ...


Antique radios...that is something I spent a lot of time on in my teens. I haven't done anything recently, but I still remember getting the sh!t shocked out of me when I was 15. My VOM was a really old Radio Shack with test leads that were worn through in spots. Whoops. As my wife says: "When we're old and grey, you'll have an entire room dedicated to things that were made a half-century before you were born." 

Actually - get this. I pitched a crazy idea to my wife years ago. I told her I'd like to have an entire basement full of "Rooms of the 20th century" complete with a TV/stereo of that era, furniture and books/games. Basically, you'd have your teens and 20's room, 30's and 40's, 50's...and so on. I'd have to stop at 80's since 1990s weren't too exciting architectually or technologically, IMO. I've also said that I wanted a "weird" house with hidden rooms and a ton of weird lighting configurations, ala 1960's neon deco. Maybe I belong in Las Vegas. The funniest part is that she actually liked the idea - all of them. 

I won't start on something like that until I've really lost my marbles. Then no one can accuse me of being crazy and needing help. They'll already know I'm too far gone. Heh.


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## chad (Jun 30, 2005)

ezaudio said:


> Actually - get this. I pitched a crazy idea to my wife years ago. I told her I'd like to have an entire basement full of "Rooms of the 20th century" complete with a TV/stereo of that era, furniture and books/games. Basically, you'd have your teens and 20's room, 30's and 40's, 50's...and so on. I'd have to stop at 80's since 1990s weren't too exciting architectually or technologically, IMO. I've also said that I wanted a "weird" house with hidden rooms and a ton of weird lighting configurations, ala 1960's neon deco. Maybe I belong in Las Vegas. The funniest part is that she actually liked the idea - all of them.


That's a cool idea. I really like it! Problem is that you'd find a fave and stick with it  

In the old abode I had multiple audio rigs... all of different era's, locale, etc. I thought it was cool, the ex could have cared less


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## chad (Jun 30, 2005)

ezaudio said:


> Antique radios...that is something I spent a lot of time on in my teens. I haven't done anything recently, but I still remember getting the sh!t shocked out of me when I was 15. My VOM was a really old Radio Shack with test leads that were worn through in spots. Whoops. As my wife says: "When we're old and grey, you'll have an entire room dedicated to things that were made a half-century before you were born."


Cheap and rewarding most of the time. I find them at auctions, especially farm auctions. Bring them in, give them TLC, tinker, etc. It's electronics and woodworking all wrapped up in one. 

It also gave me a fond interest in the "Magic Eye" tube, love them, just fascinating. 


Chad


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## AcquaCow (Nov 7, 2007)

ezaudio said:


> I wouldn't replace all of them. Save yourself some time and chalk it up to a bad die bond or something.
> 
> EDIT: Sorry for ignoring you, Dave. I got a little carried away.


No prob, I'm not in too much of a rush, but the anticipation of being able to actually fix this amp for as little as $5 makes me giddy.

You'll have to explain die bond and let me know what other materials I'll need to swap this part... any kind of special thermal paste/glue I should use to re-stick things down once I unscrew them to get at the underside of the board.

Thanks,

-- Dave


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## AcquaCow (Nov 7, 2007)

Alright, so the input stage on that amp has been great ever since swapping the IC.

But now I have a problem with another 3555...

The amp has lost all mid-range output and only outputs highs.

I figure it's just one more singled failed component, but don't even know where to start trying to figure out what is foobar.

Ideas?

Thanks,

-- Dave


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## Infinity (Jun 28, 2005)

Did the 3555 have the X-over stage, or did that start with the following v12's? I can't remember- all my 3555's were stolen


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## AcquaCow (Nov 7, 2007)

Infinity said:


> Did the 3555 have the X-over stage, or did that start with the following v12's? I can't remember- all my 3555's were stolen


All it has is an HP/LP/Off switch... nothing adjustable.

<== cleaning a 35*53* in his lap right now (It's near-mint, just dusty).

-- Dave


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## an2ny888 (Jun 27, 2008)

a bit ot... how do these 3553 and 3555 amps fare compared to newer amps, sq wise?


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## Infinity (Jun 28, 2005)

They're VERY clean amps, they just lacked a bit of the balls to run subwoofers that some of the other amps of the time had.


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## sqshoestring (Jun 19, 2007)

I have three 3555 sitting here, got into one had short in the transformer leg but still has too much offset. Just got caps to try in it. Second one roasted the voltage regulator pretty bad but the PS runs and looks excellent otherwise and have parts for it, should be able to rebuild it. Third one is a little rough but I might be able to refinish it have not checked guts yet. They all have uPC1270h in them, some of the older alpine use the 1225 IIRC.

I've used a few of the old alpines (35xx) and ratings seem right on IMO, but they sound good and distort with some grace even if they don't have the power of some other old amps. They also run warm I use a fan, and the smaller ones don't like to make bass (they do but clip easily) but will run mids/highs well. Issue with the old ones is the DIN pita to mess with, but I have one I've run hard on/off since the '80s, and never touched it...so the build quality is there.

I've never run a 3555 but will soon. If I like them and can't fix the third one, I might try to fit a class D into the sink for subs since they mount transistors on risers anyway. On the other hand I'm near done with a mrv-t757 and t407 that could work together for something, but they are completely different and all mosfet amps. Or I have a newer mrv-f345 and matching m301 that might work. Too many amps here I think, need to figure out what ones I don't want and drop them. Have a F353 5ch in the car right now, and there are some other alpines here someplace.

I never liked 4ch for subs and still don't. I'm sure some are built for it, but I've seen too many that are toast from it. I would guess this 3555 with the offset was run on subs, the xovers were set to it, and they baked it. Might have vibrated the transformer as well and they are not flimsy.


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## Infinity (Jun 28, 2005)

I liked teh 3555's, and others from the series I had, but Alpine's true grace was the next series, the V12's. The MRV1000 was true beast for it's time. I had a pair, combined with an F300 and an F400 running a whole lotta' **** in a T-Bird. It was loud, obnoxious, accurate, and best of all *FUN*.


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## sqshoestring (Jun 19, 2007)

Friend of mine has two mrv-1000, I have a 1002. He was planning on running two large boxes in an SUV with the 1000s but has not got to that project yet, I have no doubt they can deliver. Not sure I will ever use the 1002 because I always run class D on subs, and I don't think I need that much on even midbass...well maybe some day if I get a larger car it will fit in, it is not a small amp either. Nice amp, more or less a dual mono inside. The 757 and 407 are V12, leads me to think the V12 means mosfet amp. The newer and older amps are BJT outputs (class ab), even a Chinese mrp-F250 I looked at last year.


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## an2ny888 (Jun 27, 2008)

tnx for the feedback, i myself have a 3553, 3555, mrv-1000, mrv-f400, and a 3539.
out of the bunch the 3539 sounded the most musical to me, though it does make a squealing sound momentarily when it powers up, probably needs to get the input cap replaced.
i also like the acoustic compensation feature on the 3555 and 3553, gives the low end a nice bump without being too bloaty


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## karotsusu (Jan 9, 2011)

help me..have alpine 3553 that pcb board already burn on driver transistors (C3421 and A1358),can somebody help me to show a back view(soldering side)..mine already burn & crack at the soldering track..also need help a spec & value for ZD501,ZD502,R528..this component already burn too..

thanks all expert here..


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