Jl audio 500v2 nighmare from hell amp help needed

[ivkata]

Hello just got this next nightmare from Jl audio .The last month i probably bough and sold over 1o of those amps and the only reason i buy them is couse they sell good and u can actually make a profit and not work for free.So i got this amp with all bad ps irfz44n .I change them all and instaled all new gate resistors 47ohms.Now when power is applied the amp comes on for 3-4 sec and i hear click inside and will power off then on aggain and aggain.Just removed the output transistors and without them the amp stays on .I even swaped the output transistors with one form known good amp and the same story just the amp stays longer on 10sec.without the output transistors i mesured the voltage at the conector by the power terminals
and im seeing a slight diference compared to known good amp

pin 1 -5.5v known good showd 0.00v
pin 2- -16.4v
pin 3- 15.3
pin 4- 6 v
pin 5- 14.5
pin 6- 14.7
pin 7- 0.00v
pin 8- 14.4
pin 9- 14.5
pin 10- 0.00v


Please if u have any guess what might be the ishue i will try everything

 

[Perry Babin]

Please post a photo of the inside of the amp. I've never worked on a v2 (as far as I can remember) so I need to see what you have.

I'm not sure what the voltages on this amp should be. The information I have is from a v1, rev10.

In the future, use a ':' instead of a '-' as a separator. It's less confusing.

 

[ivkata]

main board is rev.11 .sorry for the separator .took few pictures.One more question for u.I have 2 other models jl audio 300/4 and 500/5 and both have some kinna water damage and i was wondering should i even bother to look on them.there are many shorted ic chips and the same with the driver boards

 

[ivkata]

[URL=http://www.turboimagehost.com/p/5193986/PB130064.JPG.html] [/URL]

 

[Perry Babin]

If the water damage is extensive, they're not likely to be worth the effort.

 

[Perry Babin]

Do you see any signs of overheating on the two filter inductors?

When the outputs were in the circuit, were they overheating?

 

[ivkata]

that first one closer on the pictures kinna smells a little like burn shows allmoast 0.00 oms

 

[Perry Babin]

The DC resistance will be very low. That's normal.

Does the yellow tape appear darkened or melted?

 

[ivkata]

i can really tell if the outputs were overheating ,I didnot let the amp run long to prevent further damage.with voltmeter on the speaker conectors there was no dc voltage.the tape looks darker maybe i should take it off to inspect it

 

[ivkata]

ok so that filter inductor was burn inside.Right in the middle there were some burn coils and melted coating.with the inductor gone and outputs installed the amp powers on just fine.Question can i use inductor form older model jl or it have to be da same.

 

[Perry Babin]

Any that look the same should be the same (from my experience). If you have an inductance meter, compare the good inductor in the amp to the donor inductor to confirm that they are the same.

 

[ivkata]

i dont have one .do u have one will pay

 

[Perry Babin]

Do you another 500 that you can pull one out of?

 

[ivkata]

nope i dont have a donor 500/1.the other amp that u were helping to repair have one large inductor.I dont wanna take it off sinse this amp is allmoast done so why mess it aggain,pluss the copper coils inside are thicker

 

[Perry Babin]

As far as I know (correct me if you find that I'm wrong), the only way to get new replacement parts is to pay JL to repair it. If you don't want to do that, you'll have to get one from a donor/junk amp. It may be possible to make a new one but that's likely more trouble than it's worth.

 

[ivkata]

this guys at Jl audio wont sell u even a resistor if u need it.they are asking 180 flat rate for the repair of any amp .I paid 60 bucks for this amp so i will have to buy one more just for that inductor.back home i could have that one redone for few bucks but here .....Nowadays electronics is so disposible

 

[807tubenut]

Measure the inductors, inductance (2~10uh might be ballpark?) and then rebuild the bad one, with insulating tape, and the same wire gauge over the old bobbin, not to hard, advanced DIY at best. Challenge yourself!

Ill be here to help.

 

[ivkata]

Im just a baby in the audio repairs and i dont have inductance meter at this time.who actually sells transformer wire so i can get some.I can count the windings easy sinse insteand of one thicker wire like the old slash amps this one have 7-8 thinner wires together .

 

[Perry Babin]

It's going to be difficult to lay down the windings as tightly as the original windings. If you attempt it, wind them tightly and make each layer as flat as possible. Unless you have wire on hand, you'll need to measure the wire with a dial (or digital) caliper to determine the gauge. Measure where there is no epoxy and, if possible, where the insulation has been burned off. The wire is sold in 1/2 gauge sizes so the measurement is critical.

For reference, I've measured several of the inductors and they were ~50uH.

 

[807tubenut]

50uf you say? Yea, that takes more to wind!