JL Audio 500/1

[mike49504]

well guess ill have to wait til morning to see if i can get one the last diode i had fell on the floor and well i cant find it

 

[mike49504]

Just got around to ordering a diode for this amp.. Is there anyway i can use a leaded diode right now to continue to troubleshoot this amp somemore??

 

[mike49504]

Ok Nevermind on the diode i found one at a local shop..

Here are the voltages i get on the 10 pin connector now..


Pin 1: 5.02
Pin 2: 0.02
Pin 3: 13.85
Pin 4: 5.64
Pin 5: 13.17
Pin 6: 11.86
Pin 7: 0.62
Pin 8: 11.67
Pin 9: 10.81
Pin 10: 0

 

[Perry Babin]

There's a 5v regulator on the main board near the low voltage transformer. Post the voltage on its terminals.

 

[mike49504]

Leg 1:10.79
Leg 2:0
Leg 3:5.02

 

[Perry Babin]

Do you have supply voltage on all of the op-amps.

 

[mike49504]

ON pin 4 of all op-amps i get 0.61 volts

On Pin 8 of all op-amps i get 1.33 volts

 

[Perry Babin]

What's the DC voltage on the legs of the transistor standing near the regulator?

 

[mike49504]

LEG 1:0
LEG 2:13.65
LEG 3:0

 

[Perry Babin]

Do you see any burned resistors in the area of the board shown below?

Are any of the transistors or diodes in that area defective?

 

[mike49504]

all resistors look good and i tested the transistors and diodes they all test fine..


Wondering 1 thing how do i tell if the 4427 driver is bad for the outputs ?

 

[Perry Babin]

You can compare the input and output signals.

Do you have 12v on either end or the large 2.2 ohm resistor on the narrow end of the preamp board?

 

[mike49504]

1 end measures 10.60 volts other end is 11.50 volts

 

[mike49504]

Ok im gonna order some new outputs for this amp along with a driver IC ..


Does anyone know the part number for the Driver IC ( U500)

It looks like the markings are AS4427 Just wondering if anyone knows the full part number for this IC

 

[Perry Babin]

MIC4427 or TC4427

Make sure you get the correct width (between the rows of pins). I think they make these in the normal SOIC and maybe 2 other SMD packages. I think you need the 3.9mm package.

 

[mike49504]

Ok i replaced the MIC4427.. I ordered it from Future electronics the part number i orderd is MIC4427ZM..

After replacing it and powering the amp up R613 went up in smoke..


Does anyone know the value of that resistor its right next to the 7805 ?

 

[Perry Babin]

It's a 0.1 ohm from what I can see in photos.

 

[mike49504]

Is there a good sub for the IRLZ34N (Q612) that also is defective. ?


Also is it normal to have only 16.4 ohms between pads 2 and 3 for the 7805 (U601) ?

 

[Perry Babin]

It's a logic level transistor so you should use a logic level transistor if you use a sub. Standard transistors are likely to overheat and fail from low drive voltage (not driving the transistor into saturation).

The regulator would probably run hot if it had to drive into that resistance. A junk board I have here reads 200 ohms without the preamp board being plugged in and 195 ohms with the preamp board plugged in.

 

[evianamp2011]

Hey mike have you taken off the pre-amp board? If so did you notice that the power terminals blocks are a about 1/8" away from the pre-amp board? And if they make contact you could have problems. Just throwing that in, something to look for.