What to look for when diagnosing an amplifier?

[turtlestrap]

Hi, I recently bought an amp off a buddy and he said it worked but when I installed it into my car, I couldn't get any power from it. No lights came up at all. The fuses are all good. I opened it up and it looks pretty normal. Nothing looks burnt or anything.

Problem could be with my electrical or something, but I don't have a multimeter to check right now. The amp is a Memphis 16-MC600D, 5 channel amplifier.

Where are the areas I should inspect more closely?

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[murph 10+ year member]

Definitely outside of my knowledge range to give you a full run down. It looks like you may be missing a few piece of the board. It looks like it may have been repaired before as well. There looks to be some oxidation on the board and with the age of it cap replacement would be something to consider. There could be a million reasons. It really needs to be in the hands of a professional.

 

[turtlestrap]

Definitely outside of my knowledge range to give you a full run down. It looks like you may be missing a few piece of the board. It looks like it may have been repaired before as well. There looks to be some oxidation on the board and with the age of it cap replacement would be something to consider. There could be a million reasons. It really needs to be in the hands of a professional.

Where does it look like it's missing a few pieces?

Edit: Just looked again and the board (green part) looks really clean and no oxidation. I don't see any places where something could be missing either is there a way you can show me? Are there any places that will test the amp for me or look at the components inside it?

 

[murph 10+ year member]

Where does it look like it's missing a few pieces?

In pictures 4 and 5.

 

[turtlestrap]

I don't think there's anything missing, I found amp guts from another website:

And here's what I think you're talking about on picture 4:

But what do you mean on picture 5?

Thanks for the replies by the way //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[fasfocus00 5,000+ posts]

did you meter your connections or are you just going off of the fact you have a fuse?

 

[turtlestrap]

did you meter your connections or are you just going off of the fact you have a fuse?

I don't have a multimeter to check, so I was planning on spending 5 bucks to take it to the stereo store tomorrow to have them bench it.

 

[hispls 5,000+ posts]

There's so much that could be toast in an amp that you can't see just by looking. On the bright side, that's a nice classic amp there so definitely worth the cost of a repair. DO NOT cheap out when sourcing a shop to do the repair DB-R in Texas, Ampmedics in Florida, or Zed Audio in California, and Sound West in Tacoma are all competent and reliable. The guys that do solid work aren't cheap and have a rather slow turnaround. If guy can do it tomorrow it's likely he's a hack because the reputable shops usually have a stack of stuff to repair.

 

[massivespl]

If amps not ever powering on check your fuse from front battery power wire to back. Might have popped it

 

[Boomin_tahoe 5,000+ posts]

I want that amp.

 

[turtlestrap]

Thanks for the input, everyone //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Yeah, my whole system is kind of a mess right now, and I don't have a DMM to check if I have power from battery or remote or anything. I'll let you all know the results of the test tomorrow.

Just curious, it lists the ratings as

RMS Power @ 4 ohms 55 watts x 4 chan. + 100 watts x 1 chan.

RMS Power @ 2 ohms 75 watts x 4 chan. + 200 watts x 1 chan.

RMS Power @ 1 ohm Not Stable + 400 watts x 1 chan.

Bridged RMS Power 150 watts x 2 chan. (Chan. 1-4), Not Bridgeable (Chan. 5)

Does this mean that you can connect a DVC 2 ohm subwoofer to the amp and get 400W RMS out of the sub channel but still have output of the other channels? Or if you wire the sub channel to 1 ohm, you can't use the other channels anymore?

Because it is a total of 320W RMS if you use all 5 channels at 4 ohms, and total of 500W RMS if you use all 5 channels at 2 ohms, but only 400W RMS at 1 channel at 1 ohm? Im sure this amp is well underrated as most memphis gear is.

Any idea of what kind of power to expect out of it using it as a monoblock to power a sub @ 2 ohms using the subwoofer channel and not using any of the other channels?

 

[Boomin_tahoe 5,000+ posts]

Uh I think those specs are wrong for that amp. If memory serves me right the sub ch alone will do 1100@ 1 ohm.

 

[garychoffmann 10+ year member]

600d is the baby bell 1100d is the big belle with the 1100 watt sub channel.

 

[turtlestrap]

Sooo... This might be funny or it might not, but here it goes:

I took the amp to a local audiophile shop, literally called Audio File. They hooked the amp up to a power supply and it powers on..

They used a signal generator to make sure all the channels worked too.

So, It must have something to do with my electrical, right?

I go to my car to see what is getting power to it, and what is not. I have a bundle of wires in my trunk from old installations and its just sitting there. Turns out, last time when I hooked the amp up, I was using a remote wire from that bundle that wasn't connected to anything.

Long story short, amp works perfectly; I'm an idiot that hooked up a remote wire that had wasn't hooked up to anything.

 

[adulbrich 5,000+ posts]

Sooo... This might be funny or it might not, but here it goes:
I took the amp to a local audiophile shop, literally called Audio File. They hooked the amp up to a power supply and it powers on..

They used a signal generator to make sure all the channels worked too.

So, It must have something to do with my electrical, right?

I go to my car to see what is getting power to it, and what is not. I have a bundle of wires in my trunk from old installations and its just sitting there. Turns out, last time when I hooked the amp up, I was using a remote wire from that bundle that wasn't connected to anything.

Long story short, amp works perfectly; I'm an idiot that hooked up a remote wire that had wasn't hooked up to anything.

Haha, its good the amp is ok. I'd rather feel like an idiot than have broken equipment