Not DIY but I need some assistance.
I purchased a Lepai LP-7498E with the TDA7498E amplifier board.
When I first connected it and powered it up it worked great.
After turning up the volume to higher levels the protection kicked in and it shut down.
I disconnected the power supply and checked my wiring but didn't notice any issues.
I tried it again and there was no sound output.
I thought perhaps it was because I ran it on a 4 ohm load, so I tried an 8 ohm load and there was still no output.
I swapped the power supply but that didn't work either.
I tried another set of speakers but still no sound output.
I opened up the case and didn't see any visible problems, no popped caps, no burn marks.
What troubleshooting steps should I perform to find the fault?
Any help would be greatly appreciated.
I purchased a Lepai LP-7498E with the TDA7498E amplifier board.
When I first connected it and powered it up it worked great.
After turning up the volume to higher levels the protection kicked in and it shut down.
I disconnected the power supply and checked my wiring but didn't notice any issues.
I tried it again and there was no sound output.
I thought perhaps it was because I ran it on a 4 ohm load, so I tried an 8 ohm load and there was still no output.
I swapped the power supply but that didn't work either.
I tried another set of speakers but still no sound output.
I opened up the case and didn't see any visible problems, no popped caps, no burn marks.
What troubleshooting steps should I perform to find the fault?
Any help would be greatly appreciated.
Are you sure about this? The TDA7498E datasheet shows 4ohm (stereo) and 3ohm (mono) output graphs. Or is it just the Lepai implementation that won't work at 4ohm?
TDA7498E - 160W+160W dual BTL class D audio amplifier - STMicroelectronics
Read it for yourself.
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00244535.pdf
TDA7498 E is slightly higher power but I still would stick to the other standard spec sheet.
Have you measured anything yet?
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00244535.pdf
TDA7498 E is slightly higher power but I still would stick to the other standard spec sheet.
Have you measured anything yet?
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Jon, you've linked to the TDA7498 datasheet, not the TDA7498E one.
The TDA7498E works with 4 Ohm, BTL even 3 Ohm. At least it should according to the datasheet. To my experience it does not run safe though, the output pins of the IC will melt together or burn up and the protection does not prevent that in the long run, so Jon was right there aside from the datasheet.
The best hint it does not like low impedances is given by the the BTL power stats, it is much lower than the stereo power specs, 2x160W vs. 220W instead of 320W which would usually to be expected (and also tells it will not output 160W on both channels at the same time). Numerous TDA7498E boards already burnt up from a lot of ppl and I very much suspect it has happened here too, so I would not recommend it using it with low impedance at all.
Besides that, a lot of 4-Ohm speakers actually have a minimum impedance of around 3,3 Ohm in some parts of the frequency range. There are other amps which can cope with low impedances a lot better, the STA516 boards (Sure i.e.) or the L15D/L20D/other IRS2092 boards i.e., which would provide a better solution overall, especally in the bass/sub range.
The TDA7498E works with 4 Ohm, BTL even 3 Ohm. At least it should according to the datasheet. To my experience it does not run safe though, the output pins of the IC will melt together or burn up and the protection does not prevent that in the long run, so Jon was right there aside from the datasheet.
The best hint it does not like low impedances is given by the the BTL power stats, it is much lower than the stereo power specs, 2x160W vs. 220W instead of 320W which would usually to be expected (and also tells it will not output 160W on both channels at the same time). Numerous TDA7498E boards already burnt up from a lot of ppl and I very much suspect it has happened here too, so I would not recommend it using it with low impedance at all.
Besides that, a lot of 4-Ohm speakers actually have a minimum impedance of around 3,3 Ohm in some parts of the frequency range. There are other amps which can cope with low impedances a lot better, the STA516 boards (Sure i.e.) or the L15D/L20D/other IRS2092 boards i.e., which would provide a better solution overall, especally in the bass/sub range.
Can anyone give me some direction on what and where to measure?
I have measured 36v from the power supply to the amp.
What else should I be checking to troubleshoot this amp.
Thanks
Noob needs assistance
Can anyone give me some pointers on what pins to test for voltage?
I learnt a bit about Op Amp circuits during my Instrumentation Mechanic Apprenticeship, but not enough to know what I'm looking for on this board.
Also, there is an LED on the board (L5) that stays red lit, is this normal?
From what I can tell, I think the amp has gone into protection and is perhaps stuck in "Standby" mode.
Either that or it's completely shot.
Thanks in advance
Can anyone give me some pointers on what pins to test for voltage?
I learnt a bit about Op Amp circuits during my Instrumentation Mechanic Apprenticeship, but not enough to know what I'm looking for on this board.
Also, there is an LED on the board (L5) that stays red lit, is this normal?
From what I can tell, I think the amp has gone into protection and is perhaps stuck in "Standby" mode.
Either that or it's completely shot.
Thanks in advance
I can't help on what to test and where, but I'd suggest a good read of the datasheet linked above to start with.
I'm guessing the red LED is nothing other than an indicator of power to the board.
Have you popped the cover? If so, does anything look obviously burnt, or other wise stressed?
Parts Express sell this particular amp, with lots of reviews and Q & A:
Lepai LP7498E 200W Class D Stereo Amplifier with Bluetooth aptX and Power Supply
May be worth your while posting a question there?
I'm guessing the red LED is nothing other than an indicator of power to the board.
Have you popped the cover? If so, does anything look obviously burnt, or other wise stressed?
Parts Express sell this particular amp, with lots of reviews and Q & A:
Lepai LP7498E 200W Class D Stereo Amplifier with Bluetooth aptX and Power Supply
May be worth your while posting a question there?
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I've been using 7498E on my guitar amp with 8-ohm load sound was decent for practice only used one channel my output power board on my amp was toasted so this one did the trick...BUT after about 6 months I was jamming and suddenly it went out no output, noise anything...read the internals have protection that would open the ckt and be back after normal values come back. I was using it with 39V (so I thought I was pushing my luck) put 16V still nothing tried the other channel and it worked so back to business I thought went for another jam session and almost at the end of the session around 3 hrs it goes out as well this time I powered with 36V. Haven't had the time to power with lower voltage to see if it comes back or it's gone already
What a too high voltage did on damage isn't undone by connecting a lower voltage PS. The IC was very likely damaged at the first time it switched off. The protections on the TDA 7498E aren't the most relyable either, I've seen a lot of these amps being fried. I still have mine but I don't use it, it sounds too bad.
To leave one channel without load can also damage the amp, if the board isn't well designed. Because of the phase shift, the output filter choke can result in a higher voltage peak than the ps delivers, esp. if the voltage is high or even well above the maximum Vcc voltage spec. If you don't want to use the 2nd channel on the next amp, put a 50 Ohm/5W resistor on the output channel and short the input of it so it doesn't get a signal (like the noise when you plug the guitar in).
To leave one channel without load can also damage the amp, if the board isn't well designed. Because of the phase shift, the output filter choke can result in a higher voltage peak than the ps delivers, esp. if the voltage is high or even well above the maximum Vcc voltage spec. If you don't want to use the 2nd channel on the next amp, put a 50 Ohm/5W resistor on the output channel and short the input of it so it doesn't get a signal (like the noise when you plug the guitar in).
hi i found this case ,there pins 21 is mute there voltage should be 3.3V .what was happen is amp is protection on ,so you have to give kick start ,use 30K resister power line to pin 21 ,then it will start again