Just got this in, went to test it and noticed soon as it’s turned on it starts cycling between low/normal idle current to very high, actually maxing out PS into CC mode, back down to low and back up about every 3 seconds. I have never seen an amp do this before, would like to find out if anyone has seen this before I give it some real power to test it as I don’t want to make the problem worse. There was some ?dried soda gunk? near knobs/terminals but nothing on the boards inside, doesn’t look like it’s ever been serviced either. Was told it worked.
Any insight greatly appreciated, searching the net didn’t result in any answers :/
Any insight greatly appreciated, searching the net didn’t result in any answers :/
Q404 & Q405 are testing bad, along with single rectifier (I think?) I don’t know how to actually test a Rectifier and I’ve looked online, ordered new LCR tester and sent back the junk one so waiting on that :/
Can I use IRF540N in place of IRF540? Amps go from 22a to 33a, voltage stays the same at 100v, and resistance is lowered from .077 to .044ohms, In still learning what basic specs mean for power supply mosfets but they look to be better specs all around, but most equipment is designed around very specific specs and I’d like a pros advice/opinion. Thx!
Also how do I test a rectifier with a DMM/Oscope?
Also how do I test a rectifier with a DMM/Oscope?
I'd suggest using the original part number. JL had the 540N available to them. If they thought the 540 was what they should use, they may know something that we don't. If you want to use for testing, that would be OK.
In class D amps, the specs are hard to use to know definitively what will work. Using a replacement in the class D circuit requires thorough testing in multiple amps before you can know for certain if the substitute part is reliable.
Unless you ordered a high quality LCR tester (like the BK Precision 879B), it's probably not far from useless. Learn to test semiconductors with a multimeter.
The rectifier is nothing more than 2 diodes in one case.
In class D amps, the specs are hard to use to know definitively what will work. Using a replacement in the class D circuit requires thorough testing in multiple amps before you can know for certain if the substitute part is reliable.
Unless you ordered a high quality LCR tester (like the BK Precision 879B), it's probably not far from useless. Learn to test semiconductors with a multimeter.
The rectifier is nothing more than 2 diodes in one case.
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Ty, that’s about along the lines of what I was thinking being a layman, I read multiple answers saying “suuure go ahead” and I thought that answer was too easy, like you said they designed this amp and know it better then us, lol. I think I’ll just order proper new mosfets.
New LCR meter is better but it not the one you listed or near its quality, think it’s time to just spring for a true proper meter when I’m able to.
Ty for that awesome simple answer on what a rectifier actually is, I couldn’t find for the life of me, sometimes I think I’m obviously searching for the wrong terms 😅 it tested good. I am going to start learning how to use DMM as suggested, ty
Correction: So with the blown IRF540 mosfets and rectifier removed the amp stopped maxing out current on PS every 3 seconds, idles normally, with rectifier reinstalled and other 2 remaining “good” mosfets still in it started the weird current draw back up, Max/CC mode on PS every 3 seconds, so I pulled remaining 2 output mosfets, leaving rectifier in, and it idles normally now. Going to just replace all 4 output mosfets with proper IRF540 and update thread afterwards.
ty Perry
New LCR meter is better but it not the one you listed or near its quality, think it’s time to just spring for a true proper meter when I’m able to.
Ty for that awesome simple answer on what a rectifier actually is, I couldn’t find for the life of me, sometimes I think I’m obviously searching for the wrong terms 😅 it tested good. I am going to start learning how to use DMM as suggested, ty
Correction: So with the blown IRF540 mosfets and rectifier removed the amp stopped maxing out current on PS every 3 seconds, idles normally, with rectifier reinstalled and other 2 remaining “good” mosfets still in it started the weird current draw back up, Max/CC mode on PS every 3 seconds, so I pulled remaining 2 output mosfets, leaving rectifier in, and it idles normally now. Going to just replace all 4 output mosfets with proper IRF540 and update thread afterwards.
ty Perry
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My PS only supplies max 10amps, it hits that limit and tries for more (CC mode) then goes back down to idle draw then starts climbing back up til it hits max again and does that every 3 seconds. On further testing with DMM the other 2 mosfets that didn’t “beep” show different resistance readings, which I’m sure means they are out of spec, ie: are bad, and most probably why I was getting that weird current draw?
Remove all outputs and make sure that there are no bridges between the solder pads.
Does the excess current draw change?
As a side note, the supplies draw a fair amount of current when starting as they charge the rail caps. I've never used a 10 amp supply so I don't know if that's an issue. On a 25 amp supply, they will draw more than 10 amps starting.
Does the excess current draw change?
As a side note, the supplies draw a fair amount of current when starting as they charge the rail caps. I've never used a 10 amp supply so I don't know if that's an issue. On a 25 amp supply, they will draw more than 10 amps starting.
With all output FETs removed amp powers on normally and idles below 1v
The other 2 FETs did have different resistance values even tho they didn’t “beep” on diode mode.
I will remember that, ty. I knew JL were designed different from what I’ve “heard” but I knew that idle was wacky, but then again maybe it was just trying to charge caps? Green “power” LED has always come on either way with no other LEDs lit. After I install 4 new Output FETs I’ll try letting it stay on for more then 15 secs, I limited on time when it was idling weird
The other 2 FETs did have different resistance values even tho they didn’t “beep” on diode mode.
I will remember that, ty. I knew JL were designed different from what I’ve “heard” but I knew that idle was wacky, but then again maybe it was just trying to charge caps? Green “power” LED has always come on either way with no other LEDs lit. After I install 4 new Output FETs I’ll try letting it stay on for more then 15 secs, I limited on time when it was idling weird
You need to check the drive signals before installing the outputs.
For this, you only want the low-voltage supply operating. If you pulse the remote on/off for a couple of seconds, the low-voltage supply will run for about 15 seconds. During that time, look at the gate signal. Is it a clean square wave on all gates?
For this, you only want the low-voltage supply operating. If you pulse the remote on/off for a couple of seconds, the low-voltage supply will run for about 15 seconds. During that time, look at the gate signal. Is it a clean square wave on all gates?
I got this wave on all PS Gate terminals before Rectifier literally smoked up out of nowhere (I checked for heat since it is not attached to heat sink and felt none on PS FETs or Rectifier, this is the longest I’ve had board powered on, pulled rectifier and it powered on but started drawing more then normal .8 idle current, got up to 1.2 then started smoking near rectifier socket so I killed power ...bro so frustrating but I guess it’s gona happen right, can’t wait for one to blow a high voltage cap, heard those are super fun ...think I’m gona crash for the night.
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Please explain:
started smoking near rectifier socket
Did you check the drive signals before you installed the PS FETs (preferably with a loading capacitor)?
started smoking near rectifier socket
Did you check the drive signals before you installed the PS FETs (preferably with a loading capacitor)?
G’morning, so the underneath of the socket fizzled first, like literal sparks, looks to be from middle socket of rectifier, same area after pulling rectifier started smoking and amp started pulling extra current, killed power ASAP, no damage on board whatsoever though, weird, not even from fizzle area that left a dark mark on my bench, and it’s was a clean reinstall of rectifier too, no solder bridges, etc.
I have never pulled PS mosfets since they tested good and we’re getting a square wave, prolly a huge newb move right?
Should I always pull all FETs when I get a problem amp in testing section by section confirming all is good before sending power to components? Seems like the best practice.
Is that considered a good/decent square wave? JL aren’t known for decent though, should a clean square wave look as good as the compensation outputs on Oscilloscope or is that just the higher quality brands? I will be pulling all PS FETs here in just a few and keep an eye on what is exactly smoking, it’s coming from underneath tho near rectifier sockets. I’ll try to record it
I have never pulled PS mosfets since they tested good and we’re getting a square wave, prolly a huge newb move right?
Should I always pull all FETs when I get a problem amp in testing section by section confirming all is good before sending power to components? Seems like the best practice.
Is that considered a good/decent square wave? JL aren’t known for decent though, should a clean square wave look as good as the compensation outputs on Oscilloscope or is that just the higher quality brands? I will be pulling all PS FETs here in just a few and keep an eye on what is exactly smoking, it’s coming from underneath tho near rectifier sockets. I’ll try to record it
The first “fizzle & spark” large enough to leave a black soot mark on my bench was from the bottom of the board from middle Rectifier socket (Anode) you can see where it slightly damaged board near pad(via?)
I’m pretty sure that area, bottom Rectifier anode pad, is what smoked the 2nd time when I was probing PS gates during and after low voltage mode.
Rectifier has equal resistance on both sides btw, .470/.471.
I removed all FETs and probed PS gates during low voltage mode and during normal mode, no smoking this time and these are the square waves recorded. (I should have adjusted volts/div for greater accuracy)
I’m pretty sure that area, bottom Rectifier anode pad, is what smoked the 2nd time when I was probing PS gates during and after low voltage mode.
Rectifier has equal resistance on both sides btw, .470/.471.
I removed all FETs and probed PS gates during low voltage mode and during normal mode, no smoking this time and these are the square waves recorded. (I should have adjusted volts/div for greater accuracy)
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It's not a socket. It's a solder pad and via.
The smoke was likely due to a bad connection.
Are you sure that that's resistance? That looks like the readings from diode-check mode. 0.470v.
Low voltage mode?
The smoke was likely due to a bad connection.
Are you sure that that's resistance? That looks like the readings from diode-check mode. 0.470v.
Low voltage mode?
Ahh ok, ty.
And you are correct, that is the voltage readings, I was using a DMM that had both Diode mode/resistance mode as 1, have since switched to my better DMM that separates the 2 modes since trying to learn to use my DMM more when troubleshooting. I get about 2.3mOhm each way and about 500mV each way as well on the rectifier when removed from board.
Is there a way to kick in low voltage mode other then pulsing remote, I am physically connecting and disconnecting the 12v remote (really just a jumper wire from main +12v lead) wire from amp remote terminal at speed of about 3x a second for about 5 secs but it won’t kick in low voltage mode. Can I just set my Power Supply to a lower voltage then 12v to kick in low voltage mode or is that not how it works?
As of right now I have no Mosfets soldered into board, it powers up, out of protect, and no smoking 😅
And you are correct, that is the voltage readings, I was using a DMM that had both Diode mode/resistance mode as 1, have since switched to my better DMM that separates the 2 modes since trying to learn to use my DMM more when troubleshooting. I get about 2.3mOhm each way and about 500mV each way as well on the rectifier when removed from board.
Is there a way to kick in low voltage mode other then pulsing remote, I am physically connecting and disconnecting the 12v remote (really just a jumper wire from main +12v lead) wire from amp remote terminal at speed of about 3x a second for about 5 secs but it won’t kick in low voltage mode. Can I just set my Power Supply to a lower voltage then 12v to kick in low voltage mode or is that not how it works?
As of right now I have no Mosfets soldered into board, it powers up, out of protect, and no smoking 😅
I actually have no idea, I assumed low voltage mode was the amps RIPS system, or some other system, running amp and producing output power on lower voltage.
I should be more clear when I saw powered up, I meant amp seems to be powered on, with a green indicator light (and not smoking ...lol)
From what I’ve read and watched it seems JL amps are very different from typical Korean half bridge designs, and much more complicated. I don’t know if I’m ready for a JL repair as from what a layman can tell their tolerances, etc are much tighter, and they do give a green “powered on” led even when something is wrong, I forgot what I read about it but ya, JL amps kinda make me nervous, they all kinda do thiugh ...lol. Gota start sometime tho, I want to be proficient in all designs someday.
I should be more clear when I saw powered up, I meant amp seems to be powered on, with a green indicator light (and not smoking ...lol)
From what I’ve read and watched it seems JL amps are very different from typical Korean half bridge designs, and much more complicated. I don’t know if I’m ready for a JL repair as from what a layman can tell their tolerances, etc are much tighter, and they do give a green “powered on” led even when something is wrong, I forgot what I read about it but ya, JL amps kinda make me nervous, they all kinda do thiugh ...lol. Gota start sometime tho, I want to be proficient in all designs someday.
RIPS?
In similar amps like the JL 500/1, the green LED requires nothing more than remote power to light up. It's not like other amps that power the LED from a secondary power supply that must be running for the LED to light up.
When you 'pulse' the remote, you only need to touch and remove the remote voltage. That should give you 15 seconds of low voltage supply if it's like the 500.
Does the low-voltage supply start when you pulse the remote in that way?
In similar amps like the JL 500/1, the green LED requires nothing more than remote power to light up. It's not like other amps that power the LED from a secondary power supply that must be running for the LED to light up.
When you 'pulse' the remote, you only need to touch and remove the remote voltage. That should give you 15 seconds of low voltage supply if it's like the 500.
Does the low-voltage supply start when you pulse the remote in that way?