JL audio E1400D

[mike49504]

I recieved this amp in for repair and the outputs where shorted i replaced all of then Irf540's I put new Irf540N's back in it. I also replaced the 47 and 10 ohm resistors.

Amp powers up But its not producing NEG rail voltage .


Any thoughts on what to check?

 

[Perry Babin]

Most of the JL class D amps have no negative rail voltage.

 

[mike49504]

So on the Irf540's 2 of them have 70 volts on the middle legs the other 2 no voltage present on them. Is that normal or is there a problem somewhere?

 

[Perry Babin]

One group of parallel outputs should have rail on the center leg. The other group of parallel outputs should have their 3rd leg connected to ground. The 3rd leg of the first group and the center leg of the second group should be at 1/2 of rail.

 

[mike49504]

Ok with black probe on ground terminal 1 group of outputs 70 volts of rail on middle legs.

Next group of outputs red probe on B+ terminal i have 13.8 volts on 3rd legs


What do i need to check next since i have no output ?

Also dont know if this helps or not but only have the green LED's are lit on the board

 

[Perry Babin]

Do you have 0v DC on all of the speaker terminals (black probe on ground terminal)?

Is the protect LED lit?

 

[mike49504]

No Dc on any output terminals. Proctection light is not lit.

I noticed the regulators 317 and 337 are getting hot very quicly though

 

[Perry Babin]

Do you see a square wave on any pin of either of the ICs marked HC132 on the driver board?

 

[mike49504]

any other way to check it? I need a new scope mine was sitting on the shelf and came crashing down and hit the floor now it doesnt work right

 

[Perry Babin]

I don't know enough about this amp to check it any other way.

 

[mike49504]

Whats a good scope wondering what you would recomend since i need to buy a new one

 

[Perry Babin]

What do you want to spend on it?

 

[mike49504]

well right now probably about 150.00 since i just spent alot getting my truck fixed

 

[wondernutz]

not to be a thead jacker or anything but I have a similar amp its a JL e1200 I had a couple shorted outputs I think they were IRF540N's there were a total of 6 and I changed 3 I powered it up and I dident have a protection light anymore and the amp produces clean sound but as soon as I cranked it up it blew one of the 540 I just installed any ideas

 

[Perry Babin]

I don't know what the original parts were but if the originals were IRF540s and you used IRF540Ns, that could be the reason they failed. If you order new parts for it, try the IRF540As (produced by Fairchild).

 

[Perry Babin]

Mike:
If you're going to buy a used scope, post (or email me) the auction numbers (assuming eBay) and I'll try to help you get a good one. Only consider scopes with locked waveforms displayed or a guarantee that the scope is in good working order. I'd suggest Tektronix scopes but they're relatively expensive right now. B&K also makes decent scopes.

 

[wondernutz]

I don't know what the original parts were but if the originals were IRF540s and you used IRF540Ns, that could be the reason they failed. If you order new parts for it, try the IRF540As (produced by Fairchild).

how do you or i guess how would i know they are an A fet not N experince??

 

[Perry Babin]

Do you have the original parts you pulled from the amp?

 

[wondernutz]

Yea they say IRF540

 

[Perry Babin]

I'd recommend that you try the non-N version.