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bjrog2 20th April 2012 02:49 PM

JL 1000/1 excessive current draw
Ladies & Gentlemen,

My name's Ben, 23, Electronics Engineer trainee. I'm well & truly a fan of car audio, and I love what i'm learning with my job.

Basically, I have my trusty JL 1000/1 v1 amplifier which when wired up & switched on, will draw excessive amounts of current (enough to rupture a 60amp fuse). It was only connected to a 500w subwoofer, and switched on at a very low volume, zero gain.

Turning everything off, and doing it again yields the same results. The power light comes on, as if it were under normal operating conditions. This leads me to think that there's a short circuit somewhere in the power supply, or the output.

Do any of you out there know of anything similar happening to these JL amps? Also, id be really proud of myself if I could fix it on my own; what would be my best methods for testing this so as to eliminate possibilities?


Perry Babin 20th April 2012 03:03 PM

Generally, if the fuse blows only after the remote voltage is applied, the output transistors have failed.

bjrog2 20th April 2012 11:34 PM

Okay thankyou.

There are no broken FET legs, ill use the part number on the case to bring up a datasheet and rest resistances between the gate, drain & source?

Perry Babin 21st April 2012 09:10 AM

On these amps, you will generally find that there is essentially 0 ohms between the drain and source if the output transistor has failed.

bjrog2 23rd April 2012 07:02 AM

g-d = gate-drain
d-s = drain-source
g-s = gate-source

Upon doing resistance measurements on the transistors, there are two SF1606G next to each other, and on either side of these there is one SF1606GA.

One of the SF1606G transistors measures 13.9kohm g-d, 0.2ohm d-s, 223kohm d-s, while the other one of the 1606G measures approx 0ohms between g-d, g-s and d-s.

Could this short-circuit 1606G be my problem? I found one dry solder on one of the IRF3707's that is next to one of the SF1606GA's and have amended that. All D-S values on the IRF3707's read 48ohms

Perry Babin 23rd April 2012 01:36 PM

The 1606s are rectifiers, not FETs.

You should read 0 ohms between the outer legs of each of the 1606s. You should not read 0 ohms between the center legs and the outer legs.

48 ohms from gate to source is OK for the FETs.

bjrog2 23rd April 2012 01:46 PM

Gotcha, it seems that one of the 1606'es is to blame here (for now). The one with 0ohms between outer legs is fine, but the other one has 0ohms between everything. Out it comes tomorrow.

Thankyou Perry

bjrog2 24th April 2012 12:11 PM

Can anybody advise of an equivalent rectifier for the SF1060g? They seem to be unavailable everywhere in Australia :| - datasheet

Perry Babin 24th April 2012 02:59 PM

Try the MUR1540.

bjrog2 26th April 2012 07:57 AM

MUR1540 has worked, and the amp now functions correctly. Thankyou to everyone who viewed and thankyou Perry for your help. You can close this thread if need be

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