Kicker SX650.1 help

[shagone]

Anyone have a schematic for a kicker SX650.1 or similar model?

i have one here with a blown up cap and open resistor from the power supply snubber circuit. or at least thats what it looks like to me. they are very near to the power supply transformer. the resistor looks to be a 2 watt but it is open and burned to where the color code is not defineable.

the resistor for the green power led was missing also but i replaced that and the amp turns on without potect mode but audio is very low. the display screen seems fine thankfully but what would cause the snubber circuit to blow like that?? the p/s and output transistors seem to check fine and there is no high current at idle. am i missing something here or can i just replace the snubber and be up and running again?

[Perry Babin]

The snubber resistors most commonly burn when the snubber cap shorts. If the cap is not shorted, you should check the operating frequency of the power supply.

The resistor is probably 100 ohms.

Have you gone into the menu and set the gain for the amp?

[shagone]

The cap looks like it was shorted for sure before because the it exploded and left black soot all over the top of the amp. i replaced it with one from the snubber of an older rockford amp that i had for parts but i'm not sure the value was the same. i also replaced the resistor with a 100 ohm 2 watt but it starts heating up and smoking fast at power up. how can i set the gain without this burning up first? it draws only 1 amp or so at idle.
the owner said he got the amp from a friend and just hooked it straight up to his kicker L7 12" without touching the settings on it he said it worked great for a week and then just fried and now has week output so this could be an issue but first i need to learn the menu for this thing. i'll search for the manual online.

[Perry Babin]

What's the value of the cap you installed?

If you don't know how to read the value, post the numbers on it.

[shagone]

i'm at work now and the amp is at home. i'll post later. it was a cap from the snubber out of a rockford dsm series amp of medium size. the kicker cap looked like a polypropolene and this one is a mylar i believe very small value but can't remember now.

i found the menu instuctions. looks too complex for the average joe for sure. i think i can handle it but i feel sorry for most of these young guys out there trying to set these up

should i pull the snubber and set the gains first? maybe my cap is not correct and heating the resistor?

[Perry Babin]

The one out of the Rockford is probably a 8200pF. The original Kicker was probably a 2200pF.

The higher value would cause the resistor to run hotter but I wouldn't expect it to cause the resistor to overheat within seconds.

If the resistor overheats with the 2200pF capacitor in the circuit, you need to measure the operating frequency of the power supply.

Removing the snubber shouldn't cause any significant problems. When it's out of the circuit, have the FETs clamped tightly to the sink. If there's problem with the supply and it's causing severe ringing, the FETs may run hot.

[shagone]

the resistor i put in was a 10 ohm and the cap was 8200pf. i changed them to 100 ohm and 2200pf and same thing, the resistor starts to smoke. i checked the gain and it was at its lowest setting. i wish i knew for sure the actual values for the circuit. i took the snubber out and the amp produced audio and seemed fine. it ran at a normal temperature and never went into protect. I didn't turn it up too high but it was at a moderate level.

if i can't get the schematic i'll have to clean up my bench and make room for my o-scope i guess to read the frequency of the power supply. maybe i am just reading the caps wrong?? how should they read again? is 223 = to 2200pf? or is it 224? i forget.

[Perry Babin]

222 = 2200pF

2,2 and 2 zeros.

[shagone]

ok thanks! i should have known that i guess but some have strange markings. maybe i'll buy some new one's instead of digging through my parts bin guessing. or i could just put a new battery in my cap tester.

would the wrong frequency of switching cause the resister to get so hot or could i just be using the wrong values still? i have a kicker DX700 amp schematic that shows a 247 ohm resistor and a .001 uf cap i think.

[shagone]

ok. i have some new wima 2200pf caps and more 2 watt 100 ohm resistors to try. i really think i had the wrong value cap in before.
i also borrowed a nice fluke 179 to measure the power supply frequency without setting up my scope.

should i measure frequency on pins 9 and 10 of the TL494 ic? what should i get? around 30khz maybe?

i also noticed that the positive and negative rails are different by about 4 volts or so. what is an acceptable offset here? what can cause this difference besides out of tolerance components?

does anyone have a picture of a SX650.1 or an open one around to verify the snubber component values near the transformer? how critical are these values and what determines them? i'm guessing the output voltage/current of the transformer has to do with it?