Kicker DX350

[Dr Zeus]

Working on this kicker amp, I cant find anything wrong on the PCB, yet when i power it up the speaker terminals have +-2vAC on them, and the scope shows this as a very clean sin wave. A signal source changes this sin wave but does it does not overcome it enough to produce anything other than added noise on the sin wave as shown on the scope.

Unless I dont know exactly where to find it, this amp does -not- appear to have the common 'TH' fuse.

The opAmps are not getting any significant voltage, nor is there any rail voltage. The power supply on the other hand is producing a regulated +-40v.

The subwooder module appears to have good solder connections to the main PCB.

Any clues? This amp is pretty clean on the inside otherwise.

[Perry Babin]

What's the DC voltage on the speaker terminals (black probe on amp ground)?

Are you sure that it has -40v of rail? Most of the 4080 amps have only positive rail.

[1moreamp]

You have a PM Dr.Zeus....C

[Dr Zeus]

DC voltage is less than 0.010vDC on speaker terminals referencing amp ground. Theres ~1.6vAC on terminals referencing ground.

The rail voltage isnt seeming to be correct in this amp. I think secondary ground tap is at the northern end of the large blue resistor front and center. This amp has 4 output transistors. Two of them have +20vDC on their center pins, and the other two outputs have +-20vAC on their center pins referencing the center ground point.

Hey 1moreamp. Thanks for lookin out but the DVD I got from Perry has this amp's schematic. I dont know where to look on it though.

[Perry Babin]

When you measured the DC voltage of 20v on the outputs, where was your black probe?

Do you read ~0 ohms between the RCA shield and the secondary center tap?

[Dr Zeus]

Im thinking the secondary center tap is at the large hole at approximately 4 o'clock on the first photo's large maroon transformer coil. It is a hole in the PCB and measures 0.8 ohms to the RCA shields.

From this point, every other output transformer's center legs measure either +21 or +42 volts. Also from this point, the positive and negative speaker output terminals all measure 21v.

[Perry Babin]

That seems normal.

You should have regulated voltage also. With the black probe on the secondary CT, what is the DC voltage on the collectors of Q10 and Q11?

[Dr Zeus]

Q10 is a TIP29C. This transistor gets a bit warm after about a minute of powered on
leg 1: 17.8
leg 2: 26.55
leg 3: 17.20

Q11 is a TIP30C
leg 1: -17.9
leg 2: -26.7
leg 3: -17.31

Also from center tap looks like the opamps are getting +-14.75vDC.

But, is it right that the speaker terminal outputs have 70vAC referencing center tap?

BTW seems this amp may have similar symptoms to a JL/1000/1 I'm working with. Maybe its just my stupid understanding of this style of Class-D. Is there any good read I may have missed on the DVD?

[Dr Zeus]

Ok I definately think this repair has gone as an ID10T error. Seems I'm just not familiar with this style of class-d. I guess when I got the amp on the bench the first thing I measured with the DVM was strange readings on the outputs and whatnot. I took it apart and everything; just to find out theres likely nothing wrong. I had the guts to try a test speaker on this amp and lo-and-behold; the amp is working just fine and dandy it seems.

The experience is my reward for working on this amp.

[Perry Babin]

The basic class D page mainly applies to HIP4080 based amps. There are additional links for 4080 based amps at the bottom of the page.

If you let me know what's not covered that confused you, I'll make changes.