I need the drive transformers for the JL1000 V2. T804/T805.
They went up in smoke when the power supply FETs failed.
They went up in smoke when the power supply FETs failed.
I guess im going to have to rewind these little bastards.
Anyone have specs on the type of wire, number of turns, etc..?
I peeled the yellow tape back and they are pretty bad. Heat scorched.
They still show continuity, but one has an inductance of 1Mh, the other about 400uH. Not good. My ring checker still shows green but im not trusting it.
One of the Vias had opened on the right hand transformer (closest to power jacks). So, i have half my MOSFETs on the right bank that dont have any continuity between G-S.
I think that via goes to ground, but Im not sure. The MOSFET configuration is kinda weird, I dont see a center-tap on the primary transformer. My guess an H-Bridge configuration? driven by the two drive transformers.
Anyone have specs on the type of wire, number of turns, etc..?
I peeled the yellow tape back and they are pretty bad. Heat scorched.
They still show continuity, but one has an inductance of 1Mh, the other about 400uH. Not good. My ring checker still shows green but im not trusting it.
One of the Vias had opened on the right hand transformer (closest to power jacks). So, i have half my MOSFETs on the right bank that dont have any continuity between G-S.
I think that via goes to ground, but Im not sure. The MOSFET configuration is kinda weird, I dont see a center-tap on the primary transformer. My guess an H-Bridge configuration? driven by the two drive transformers.
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Unfortunately your only option for replacing the shorted audio chokes is to pull known good ones from a scrap board. 🙁
I don't have any definitive information on the transformers. I think there are three independent windings that likely have the same number of turns. You could drive a 20k signal into the primary winding of the good transformer (if there is one) and see if the output is essentially the same signal as the input.
On the output, one winding is connected to ground. The other output has one terminal connected to the source and the other terminal connected to the gate of the FETs that it drives. This winding floats.
On the output, one winding is connected to ground. The other output has one terminal connected to the source and the other terminal connected to the gate of the FETs that it drives. This winding floats.
Well scrap JL1000s still go for too much money, so this thing is pretty much junk unless I rewind the trafos.
As far as connections, perry, im confused. Can you elaborate a bit? 1 winding is connected to ground, Where is the other connection of that same winding going?
2nd winding is connected between gate and source? im really confused now. lol.
The only thing I have figured out is the primary winding goes to an 8-pin complementary MOSFET SOIC.
As far as connections, perry, im confused. Can you elaborate a bit? 1 winding is connected to ground, Where is the other connection of that same winding going?
2nd winding is connected between gate and source? im really confused now. lol.
The only thing I have figured out is the primary winding goes to an 8-pin complementary MOSFET SOIC.
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When you drive an FET, the drive voltage is the voltage applied from the source to the gate with the source as the reference. In standard amps, the source is grounded. In this amp, two banks of FETs have their source grounded. The drive signal appears normal for these FETs because one terminal of the drive winding is grounded with the source of the FETs.
The other two banks have essentially the same connection but since the FETs are not grounded, the gate/source of the FETs float with the floating winding of the driver transformer.
In other words... All FETs have a winding connected from source to gate, it's only the fact that two banks are floating that make it somewhat confusing.
I'm sure that you noticed that neither winding of the power transformer is connected to B+ or ground. They directly connect to the FETs. The FETs alternately drive them to B+ and ground. The power transformer drive circuit is much like the H-bridge class D amplifiers that have their outputs biased at 1/2 of rail voltage (JL class D, HIP4080 based amps...).
The other two banks have essentially the same connection but since the FETs are not grounded, the gate/source of the FETs float with the floating winding of the driver transformer.
In other words... All FETs have a winding connected from source to gate, it's only the fact that two banks are floating that make it somewhat confusing.
I'm sure that you noticed that neither winding of the power transformer is connected to B+ or ground. They directly connect to the FETs. The FETs alternately drive them to B+ and ground. The power transformer drive circuit is much like the H-bridge class D amplifiers that have their outputs biased at 1/2 of rail voltage (JL class D, HIP4080 based amps...).
I didn't note the locations in your first post and thought you were referring to the audio chokes which more often fail in my experience.
Don't junk your JL 1000/1 board, put it aside, keep a eye on Craigslist for a broken JL 1000/1, sometimes they can be had for as low as $50-$60 but you have to look everyday and act fast. Good luck. 🙂
Na, not around here. car audio is too strong in my area. which is why I have a job in the first place ;-) Unfortunately this time of year for me, is remote start season.
Not to mention we have 3 customers that are avid Craigslist buyers/sellers that bring stuff to us all the time for repair. JL audio is rather rare though around here. Most of the time its kicker, hifonics, audiopipe, and rockford, I see kicker so much so that I had become friends with one of the repair supervisors at kicker. Of course thats kind of expected as we are a kicker authorized dealer/installer. I am just a repair tech though. In the more rare department, I see kenwood, pioneer, alpine, and sony every once in a while. Head units of these manufacturers I see all the time. Amplifiers rarely. I hate fixing head units, they tend to suck. I manage though, its always the weird crap that gets me every time. Such as bad voltage regulators, bad zener diodes, and I have seen cases in JVC/Kenwood units, 1 open resistor causing no power. and this is an 0402 SMD resistor. Then with Sonys, 90% of the time is either bad processors, or bad face buttons.
The newer Sony head units with bluetooth, and all the fancy features need the processor reflown often, and the older Pioneer units the DSP/Sound processor and conditioner are dropping like flies, causing distortion or static at 0 volume.
The trend as of late is old school stuff, within the last 6 months I got a surge of old school amplifier repair and restorations.
But I digress.....
Perry, is there an advantage to running H-Bridge configuration on the power supply? Most if not all the amps I see are center-tapped push pull configuration. More current gain?
Not to mention we have 3 customers that are avid Craigslist buyers/sellers that bring stuff to us all the time for repair. JL audio is rather rare though around here. Most of the time its kicker, hifonics, audiopipe, and rockford, I see kicker so much so that I had become friends with one of the repair supervisors at kicker. Of course thats kind of expected as we are a kicker authorized dealer/installer. I am just a repair tech though. In the more rare department, I see kenwood, pioneer, alpine, and sony every once in a while. Head units of these manufacturers I see all the time. Amplifiers rarely. I hate fixing head units, they tend to suck. I manage though, its always the weird crap that gets me every time. Such as bad voltage regulators, bad zener diodes, and I have seen cases in JVC/Kenwood units, 1 open resistor causing no power. and this is an 0402 SMD resistor. Then with Sonys, 90% of the time is either bad processors, or bad face buttons.
The newer Sony head units with bluetooth, and all the fancy features need the processor reflown often, and the older Pioneer units the DSP/Sound processor and conditioner are dropping like flies, causing distortion or static at 0 volume.
The trend as of late is old school stuff, within the last 6 months I got a surge of old school amplifier repair and restorations.
But I digress.....
Perry, is there an advantage to running H-Bridge configuration on the power supply? Most if not all the amps I see are center-tapped push pull configuration. More current gain?
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JL Audio is very popular here plus I live near a large city so JL Audio amps working or otherwise pop-up on Craigslist quite often. I also know a few local installers that I can often get non-working JL amps from as well.
If you can hold onto the JL 1000/1 amp awhile PM me your address and I would say in a few weeks or so I should have access to a JL 1000/1 board and I can pull the xformers you need from.🙂
If you can hold onto the JL 1000/1 amp awhile PM me your address and I would say in a few weeks or so I should have access to a JL 1000/1 board and I can pull the xformers you need from.🙂
I don't know of any real advantage for the H-bridge in car audio power supplies. In offline switchers, I think it allows the use of lower voltage switching transistors (compared to push-pull).
I wonder if it was to prevent surge from the output stage from blowing up the entire power supply stage? But maybe not because in this case the power supply was wasted, But so was 1 entire side of the output stage as well.
All the JL1000 units I fixed had toasted output stages, but power supply always held out. This one not so much.
All the JL500s ive seen, nearly all had blown up power supplies.
All the JL1000 units I fixed had toasted output stages, but power supply always held out. This one not so much.
All the JL500s ive seen, nearly all had blown up power supplies.
It still blows at least half of the power supply FETs and since it uses twice as many FETs, I don't think that's the reason that they used that design.
I don't generally recommend 'upgrading' amplifier components but in the JL 500/1 I've been using IRF3205s in the supply and the IRF3710Z in the output stage. The newer components seem to be able to better withstand the stress until the protection circuit can engage.
I don't generally recommend 'upgrading' amplifier components but in the JL 500/1 I've been using IRF3205s in the supply and the IRF3710Z in the output stage. The newer components seem to be able to better withstand the stress until the protection circuit can engage.
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