JL Audio 1000/1

[S Merlington]

I believe U804 is defective.. LM358

I know theese are avaible is there any good subs i can stick in the amp for testing or not?

 

[Perry Babin]

U803 and U804 are not op-amps. They are NDS9952a.

The photo I'm using as a reference is below. Confirm that yours is the same.

 

[S Merlington]

Ok my mistake yes the amp is the same as the pic

 

[S Merlington]

Ill order a few of thoose and replace them..

Also is there a good replacement for the IRF3307's or do you know where i can get them?

 

[Perry Babin]

Do you mean IRFB3307Z?
http://octopart.com/partsearch#!?q=irfb3307

 

[S Merlington]

Not sure if whats in the amp is orginal or not but the part number on theese power supply fets in the amp now say IRF3707

Board is rev3

 

[Perry Babin]

Do the solder connections appear to be flow-soldered or do they look like they were soldered with a soldering iron?

Why are you replacing them if they aren't defective?

http://octopart.com/partsearch#!?q=IRF3707

 

[S Merlington]

They appear to have been replaced at some point in time..

I found 1 of them with a broken leg on it the leg was broke at the body of it ..

So i wanna replace it So was wondering since 1 of them had a broken leg should i replace all of them or how many do i have to replace ??

Also wondering if i should stay with the 3707's or switch them out since the 3707's are non stockd from the places i usually order from..

Digikey,Mouser,Arrow,Future,

 

[Perry Babin]

Mouser and Digi-Key have the IRF3707Z which should be a good replacement.

The newer version (1200/1) uses the IRF3709Z. The drive circuits appear to be similar. I would expect them to be suitable subs but I've never tried them as a sub.

 

[S Merlington]

Perry,

Do you have a high res pic of the power supply driverboard??

Aslo a high res pic of the resistors that sit directly in fron of the driverboard??

2 resistors in front of the driverboard are burnt..

The blue cap on the driverboard appears to have been touched with a soldering iron and it melted i wanna replace it but dont know the value..

 

[Perry Babin]

See attached.

1000pf, 100v, 5%.

 

[S Merlington]

Thanks,

I have the new power supply fets and the NDS9952a's on there way to me ..

Anything else i should check in this amp while im waiting for the parts to arrive?

 

[Perry Babin]

Before you replace all of the power supply FETs, I'd suggest installing the drive ICs to make sure that the driver transformers are not defective.

 

[S Merlington]

Once i install the drive IC'S how do i tell if the transformers are defective or not??

Do i just check the drive signal on the gate pads?

 

[Perry Babin]

Checking the signal and also seeing if the IC operates at a significantly higher temperature than the other one.

 

[S Merlington]

Ok replaced both NDS9952a's also replaced the FQP30N06L..

When i try to power the amp up the Power led lights up but so does the low ohms light..

Any ideas what to check next??

All outputs test good

 

[S Merlington]

Ok cannot figure out why amps low ohm
Light is on. All outputs are out of amp and it still lights up any ideas

 

[Perry Babin]

Does the low impedance LED remain lit or does the amp cycle on and off?

 

[S Merlington]

It remains lit

 

[Perry Babin]

There is a blue potentiometer near the rail caps and the inductor. There is an 8-pin op-map there. Does it have positive and negative supply voltage on pins 4 and 8?