JL Audio 450/4 repair - Need help please!!

[Jeff Mills]

Will I also need new rings for the vias (?). Sorry I’m just learning all this terminology.
I have a couple through holes missing the rings. The traces(?) are pretty short but are pretty badly damaged from the gate resistor campfire I had. I’m guessing I will need the wire method.

On a side note, I took this in to the only repair shop I could find in my area only to walk out disgusted and ticked off with how they treated and talked to me. It was so bad my angel of a Wife was about to tear into him!! What a shame he is the only dirtbag I can find to fix this.

Oh yeah, to add insult to injury he pulled a so called “medium sized repairable amp” off the shelf after he stated my 450/4 was such aBIG amp....the amp he shows me was an old rusty Directed paperweight, lol. I told him those belong in the dumpster after they blow. Who pays $100’s to fix a $20 amp?!?! WTH

Sounds like the guy had a "holier than thou" attitude maybe he should be reminded that God counts woman's tears. What a jack-a55!

 

[ResonateEngineering]

Very true indeed. I yelped him a bad review.. first time I ever felt compelled to leave a bad review. People like that bother me so much..I will send pics in 5 min stay close...

 

[ResonateEngineering]

Didn’t see how to attach pics from phone into PM?? Here are some..

 

[jlind54]

You could use thru hole resistors instead of the original SMD and bend the legs appropriately to make the correct connections. That will save you from trying to solder jumpers to SMD parts. The drivers don't look like they got too toasty, be sure to check and see if any have shorted though.

 

[Perry Babin]

This is an example of a basket-case amp I use in the shop. The 1/8w resistors are wrapped around the gate legs of the FETs. The other legs of the resistors that go to one set of drivers are connected together and then go the emitter of the drivers. Here, the drivers had damaged to board too badly so I used BD139/140 transistors in their place.You'll want to use a small, flexible wire to connect to the drivers so you don't stress the solder pads. Ise something like a strip off of a computer ribbon cable.

You also need to bend the center leg so that it doesn't form a rigid triangle when soldered into the board.

After you get the FETs soldered in, also solder the 3rd leg on top of the board in case the via was damaged.

 

[ResonateEngineering]

Thats my kinda monster. I just got PS fets and the first resistors you specified.

 

[ResonateEngineering]

I’m gonna destroy this amp. Hahaha, my First massacre.. gotta start somewhere right? I appreciate all the help, I’m all ears or eyes rather, need all the advice I can get.

 

[Perry Babin]

Before installing the FETs, measure the DC voltage on the emitters of the driver transistors. After about 10 seconds, you should read the same voltage, about 4-5v.

Have you checked the output transistors?

 

[ResonateEngineering]

I haven’t taken any readings yet. Don’t really know what I’m doing yet. I try to search as much as I can but this sites search seems wierd to me. Like it’s not giving me the right results as far as search terms. I do own a meter and curious if other parts are safe.

 

[Perry Babin]

You should not read anything near 0 ohms between the three legs of any individual output FET, no matter the probe/terminal combination.

 

[Freecrowder]

Yeah looking at the pics I dont think I would ship it out this way. Good one to get some practice on. good luck!