broken amp or faulty wiring?

[smokeyjoe03]

I have been gifted a Vibe slick A3 without knowing whether it works or not.

Plugged it in today and got protect mode, checked all onboard fuses, they're fine. As is the inline one.

Checked cable connections, they're fine.

My earth works for my other two amps when I tried them so that's fine.

When I tried it only power, remote and ground were connected so its not and RCA or speaker impendance issue.

This suggests the amps FUBAR'd, however, the protection light is only dimly lit, and gets brighter when RCA's are plugged in, does this mean anything significant?

I'm off to buy a multimeter tomorrow so I'll check the resistors inside to make sure none have blown (common fault apparently) but any ideas anyone?

 

[blupanda]

Sounds like the amp is grounding out through the rcas tbh.

Ive seen it a few times with amps where the soldering has splashed when theyre eing made and shorts it out.

Examine the board for any odd signs but tbh it may already have damaged internals as it has been powered on on its current state

Best of luck and hope you get it working

 

[smokeyjoe03]

I found with a multimeter that two of the MOSFET transistors have blown, apparently a common issue with these amps.

So desoldered them, powered it up and it comes out of protection so its fine. Just need to replace them and jobs a good-un. Got some on order so fingers crossed.

 

[smokeyjoe03]

Sorted it, soldered in the new mosfets, made sure I used a hell of a lot of thermal paste, and the amps as good as new, nothing like a freebie.

Now I have 325w running to my sub, and two spare channels with 100w going to waste. So what do I run to take advantage of the amps output? I'm looking for some decent 6.5" comps, that aren't a million quid

 

[volxstu]

Whats runing the fronts?

 

[smokeyjoe03]

Just running the vibe a3, so 2 bridged channels running 325w for the sub, and got 2 spare channel (it'll be in 3ch mode obvs) outputting 100w @ 4ohms. *all figures rms*

At the minute just got the standard speakers running off my hu, it sounds ok but the sub now has the capacity to put out a LOT of volume, and the speakers just can't keep up after a certain point

 

[volxstu]

Whack the speakers on the amp :devil: No seriously. If you keep the levels down it should give you a bit of extra volume, clarity and linearity.
Basically the chances are that you want the sub to go loud and clipping the signal to the standard speakers. You could blow the front speakers easier on the HU than having them on the amp imo.
It would be even better if the amp has the ability to have different gain levels for each side of the amp?

 

[smokeyjoe03]

It does

http://www.audiorepaircentre.com/wp-content/uploads/2009/11/slick_a3.pdf (go to page 4)

I could amp the existing speakers, I doubt I would get any real midbass out of them without breaking them though.

All the speakers I have seen so far are either underpowered or crap. Just waiting to find something that will give me decent midbass (I have no issue with builing speaker pods if need be) for a decent price and will match the power rating the amp is giving out (100w rms @ 4ohm)

 

[volxstu]

Do iiiiit. If it ruins them then its a good excuse to buy some more :devil:

 

[smokeyjoe03]

So, after I "fixed" my amp it was fine, since I installed my new comps problems have occured.

I never used the channel I fixed, the mosfets I replaced were for channels 3+4, I ran the sub from channels 1+2 bridged.

However since I wired in my comps (comps in channels 1+2 and sub into channel 3+4 bridged) the sub has been getting less and less power. Now the protection light won't go off. Its on dimly along with the power light. And its still on with only power, ground and remote connected. Seems as I've worked the new mosfets in, they have burnt out

Time to cut my losses and run I think. So now I'm looking for a decent 4 channel amp that can run in 3 channel mode.

Speakers need: min 60w, rms 120w, max 360w
Sub needs: rms 275w, max 1100w

So a 4x150w amp would suffice as most bridgeable amps just combine 2 channels power, so 2x150 and 1x300w in 3 channel mode would be perfect.

Any suggestions?