There are a few problems.
1.The preamp board came with missing resistors.I installed resistors based on photos and using my meter to determine where they go.There's pictures of before and after.Can anyone tell me if there right or post a photo of this area from a jl250/1?
The preamp board is very similar to a 500/1 but not identical(I think).
2.With just power and ground connected(no remote) the amp draws .5 amps of current and the green ON light flashes intermediately.There is also 50vdc across speaker terminals.
With remote,the amp has very low drive voltage to power supply FETs and again flashes the green light.
Switching the signal sense switch doesn't change anything.
I'm wondering if something on the preamp board is causing this due to several missing resistors initially.
1.The preamp board came with missing resistors.I installed resistors based on photos and using my meter to determine where they go.There's pictures of before and after.Can anyone tell me if there right or post a photo of this area from a jl250/1?
The preamp board is very similar to a 500/1 but not identical(I think).
2.With just power and ground connected(no remote) the amp draws .5 amps of current and the green ON light flashes intermediately.There is also 50vdc across speaker terminals.
With remote,the amp has very low drive voltage to power supply FETs and again flashes the green light.
Switching the signal sense switch doesn't change anything.
I'm wondering if something on the preamp board is causing this due to several missing resistors initially.
Attachments
I'm off by 50k on resistor at pin 13.Thanks
I'll change it.Wonder if that's causing this weird intermittent problem and excessive DC offset.
I think someone tried to repair it and shorted the remote line.I also don't see how it would of fried all those resistors.
I'll change it and post back.
I'll change it.Wonder if that's causing this weird intermittent problem and excessive DC offset.
I think someone tried to repair it and shorted the remote line.I also don't see how it would of fried all those resistors.
I'll change it and post back.
I do believe the amp is shutting off intermediately due to DC offset(30+vdc)
I'm not 100% the preamp board is in good working order yet.I'm struggling to figure out what's causing the erratic DC across the speaker terminals.
Speaker terminals to ground flucuate as well.
Any ideas what to look at?
I'm assuming the DC offset is causing me to lose voltage on pin 8 of the 10 pin connector from main to pre board.
I'm not 100% the preamp board is in good working order yet.I'm struggling to figure out what's causing the erratic DC across the speaker terminals.
Speaker terminals to ground flucuate as well.
Any ideas what to look at?
I'm assuming the DC offset is causing me to lose voltage on pin 8 of the 10 pin connector from main to pre board.
Do you measure 30v with the red probe in the positive speaker terminal and the black probe in the negative speaker terminal? If not, what is the DC voltage with the probes on those points?
Yes,across the terminals there is 30vdc or so because it bounces.
There is also DC to ground as well from speaker terminals.
At one point I had 50 volts on + terminal to ground and 20 volts on - terminal to ground.
It doesn't stay consistent because the amps cycling I believe.
But there is very high DC offset from + to - terminals intermediately.
There is also DC to ground as well from speaker terminals.
At one point I had 50 volts on + terminal to ground and 20 volts on - terminal to ground.
It doesn't stay consistent because the amps cycling I believe.
But there is very high DC offset from + to - terminals intermediately.
Pull the outputs and check them.
If they're OK, solder a jumper between pins 1 and 2 of U408.
Does that give you good drive signals at the output transistors?
If they're OK, solder a jumper between pins 1 and 2 of U408.
Does that give you good drive signals at the output transistors?
I just pulled the outputs and there all good.All voltages are still at speaker terminals with FETs removed.
I pulled the rectifier(d300) to see if amp will start.
The amp turns on (.7amp of current) with no remote.Drive signal to power supply FETs is perfect.
The green ON light does not illuminate with or without remote voltage.No lights illuminate.
Moving the switches doesn't change anything.
I pulled the rectifier(d300) to see if amp will start.
The amp turns on (.7amp of current) with no remote.Drive signal to power supply FETs is perfect.
The green ON light does not illuminate with or without remote voltage.No lights illuminate.
Moving the switches doesn't change anything.
Not that I can see.I checked across all four output locations with a meter and there consistent(high to high low to low)
I have to reinstall the rectifier to check that again..
I'm trying to troubleshoot why its turning on(partially) without remote.And with remote connected the light won't illuminate.
Unless you have a tip for this issue I'll put the rectifier back in and repost the situation momentarily.
I have to reinstall the rectifier to check that again..
I'm trying to troubleshoot why its turning on(partially) without remote.And with remote connected the light won't illuminate.
Unless you have a tip for this issue I'll put the rectifier back in and repost the situation momentarily.
Are these things famous for bad solder joints on pre amp boards? I turned it over and a resistor fell off.I put it back on,now it won't start up at all.Looks like I'm going to have to go over every solder joint at this point.
Was it one of the lower resistors near the edge of the preamp board? Two of them appeared to have bad connections but I assumed that it was an illusion since you were working in that area?
I haven't known any JL amp to have bad solder connections other than the ones that sometimes overheat (large resistors and diodes).
I haven't known any JL amp to have bad solder connections other than the ones that sometimes overheat (large resistors and diodes).
It was a 220k right beside the 324.When I got this thing it had several missing resistors on pre amp board.They actually look like they just fell off.Nice square edges still in the existing solder.
I noticed when I would hit some of the resistors with my iron they would immediately lift up like the opposite joint wasn't connected.
Let me try to get it to start back up and well go from there.
Thanks
I noticed when I would hit some of the resistors with my iron they would immediately lift up like the opposite joint wasn't connected.
Let me try to get it to start back up and well go from there.
Thanks
Perry,I can't get it to start up now.The voltages on the 10 pin header aren't what there supposed to be.Maybe you can give me an idea where to look.
This is with remote connected,signal sensing off,and referenced to ground.13.4 input
1.gnd
2..033
3.12.5
4.6.7
5.12.8
6.12.8
7..6
8..024
9.12.7
10.gnd
This is with remote connected,signal sensing off,and referenced to ground.13.4 input
1.gnd
2..033
3.12.5
4.6.7
5.12.8
6.12.8
7..6
8..024
9.12.7
10.gnd
First 250 I tried to borrow is gone. I may know of one more.
If the pin 1-2 jumper is stopping the amp from powering up, find the output pin (pin 1 or 7) that is directly connected to a 1k resistor. If it's 7, jump 6-7 on U408 instead of 1-2.
If the pin 1-2 jumper is stopping the amp from powering up, find the output pin (pin 1 or 7) that is directly connected to a 1k resistor. If it's 7, jump 6-7 on U408 instead of 1-2.
Pins 1 and 2? I'm assuming your referring to opamp bridging to check drive signal.
I havnt got that far yet.
I reinstalled the rectifier and fixed a couple solder joints and now amp won't power up.
Removed the rectifier and still nothing.
It just bounces between .1and .2 amps of current but won't start.
Earlier it would start and had power supply drive but no green light and no remote applied.
I'm assuming the 10 pin connector is the same as the 500/1.I'm trying to figure out my voltage issue based on the DVD but the traces go everywhere.
I havnt got that far yet.
I reinstalled the rectifier and fixed a couple solder joints and now amp won't power up.
Removed the rectifier and still nothing.
It just bounces between .1and .2 amps of current but won't start.
Earlier it would start and had power supply drive but no green light and no remote applied.
I'm assuming the 10 pin connector is the same as the 500/1.I'm trying to figure out my voltage issue based on the DVD but the traces go everywhere.
On the 10 pin connector, do you see any pins with voltage that's pulsing significantly (more than a fraction of a volt)?
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