Crossfire CFA602 - Power light goes bright, then dims (reoccurring

[justlikemusic]

Hello, I have been into fixing my own equipment, where i can, for a while now... I have done some basic repairs, but my knowledge is very basic. I know what each component looks like and how to get a replacement for it, but not quite what it does etc but that will come with time, and reading more of these forums!

My dilemma is my Crossfire CFA602 (White amp, looks like PPI Art series... so beautiful.) has the power light coming on when I put power to it, then it goes slowly dimmer and then straight away bright again, then fades dimmer and repeats this process.

My cabling is impeccable! I run two batteries Exide 650CCA, Century ExtraHD 700CCA N70Z in the trunk and have two runs of 4ga down the back. 4ga from Alt to battery, and 95mm 00ga grounds from front battery to engine, and same 95mm grounding the battery to the side of the strut tower. I sanded back the connections and they are beautiful. Was recently running a Crossfire VR1000D @ 1335w rms to my Digital Designs 3515 (which was the same sub running when this amp died.)

Any ideas what to check? I ran a resistance test over the transistors, and they all come up with 0.9-1.0, like most of my other amps read too so I believe these to be good. There is no smell on the board or anything that looks damaged!

[Perry Babin]

It sounds like it's going into protect mode. While the amp is cycling on/off, place the meter probes across each channel (meter set to DC volts). Does either channel ever read more than a fraction of a volt of DC?

[justlikemusic]

When it does that, when it was in the car... the sub would make a little bass followed by a big thud, then repeat the process with the light. Ill test the channel DC Volts and report back once I get home in a few hours.

[I Am An Idiot]

I think the big thud is a pretty good indication that there is going to be some DC voltage present. Chances are you have one or more shorted output transistors.

[justlikemusic]

Ok, I'll look into more thorough testing of these, because when I was just checking impedance between the three 'legs' (is all I have done), none seem shorted.