When I took my measurements, I measured across the diodes to get my voltage reading. I measured from the anode to the cathode of the diode's that I checked. That's how I found the high side on the positive speaker circuit gate voltage to be "low" compared to the rest of all the gates. If I use the power supply ground as my reference then I get like 140V as well.
Also when I measure my pin 15, I'm measuring the ground point at the driver IC I'm measuring. These amps are tricky by the looks. Maybe I'm wrong and I'm measuring my voltages/grounds from the wrong points. I just used the grounds to the respective IC's to make my measurements as that's what the IC would see.
According to the schematics I was given access to (Google view only, not print or share), the final current draw at idle for the HD 15K is as follows (I will leave the language alone):
Consumption with coolers @ 12.6V - 4.30A
Consumption with coolers @ 14.4V - 5.10A
APC pin measurement - 2.70V <--- This appears to be a protection sensitivity
Taramps says the DC offset should be below 1.00V. Mine started at 650mV or so but I changed it to less than 100mV.
Short story, I gave the amp back to the guy and he hooked it up. Upon hooking it up and before music hit it, the output fets on the negative circuit went pop once again. Before I gave it back to him, I confirmed all drive voltages, all drive waveforms, all TL720 voltages including their waveforms, and I did the current draw test according to what Taramps gave me. I ran it at idle for about an hour and set the DC offset. Then I put a 14.4V 100A power supply on it and a 1ohm 2000 watt dummy load on it and ran bass music through it. I left it for another hour and it warmed right up like its supposed to. Then I gave it back to him and then pop. Makes no sense.
So when I got it back, the input sensitivity was set to 3/4 the way up and his deck was set to +5dB on the subwoofer output. He also has a 5.0V MAX output on his deck. Apparently this can blow a Taramps amp up like nothing. I'm trying to verify this with Taramps but the guy I'm speaking to is having a hard time understanding english
. This amp's input sensitivity is listed as 220mV or something crazy. I just find it hard to believe that these don't have a range or something. But when reading posts online, they all say that these amps don't like + any dB on the head units and they live in the 2.0V out and less range.
I for one do not believe that my workmanship is what caused his amp failure especially when it worked flawlessly on my bench. I had music playing to it for about an HR and my dummy loads were screaming hot. But how can just hooking it up to a deck and then turning it on, getting the fans running then smelling smoke make any sense or happen? His system voltage is 14.4V dead on and his battery bank is large. Also his final impedance measured with a DMM is exactly 1.0 ohms. Baffling. Tomorrow I'm going to pop fresh parts in and continue investigating this thing.
Also when I measure my pin 15, I'm measuring the ground point at the driver IC I'm measuring. These amps are tricky by the looks. Maybe I'm wrong and I'm measuring my voltages/grounds from the wrong points. I just used the grounds to the respective IC's to make my measurements as that's what the IC would see.
According to the schematics I was given access to (Google view only, not print or share), the final current draw at idle for the HD 15K is as follows (I will leave the language alone):
Consumption with coolers @ 12.6V - 4.30A
Consumption with coolers @ 14.4V - 5.10A
APC pin measurement - 2.70V <--- This appears to be a protection sensitivity
Taramps says the DC offset should be below 1.00V. Mine started at 650mV or so but I changed it to less than 100mV.
Short story, I gave the amp back to the guy and he hooked it up. Upon hooking it up and before music hit it, the output fets on the negative circuit went pop once again. Before I gave it back to him, I confirmed all drive voltages, all drive waveforms, all TL720 voltages including their waveforms, and I did the current draw test according to what Taramps gave me. I ran it at idle for about an hour and set the DC offset. Then I put a 14.4V 100A power supply on it and a 1ohm 2000 watt dummy load on it and ran bass music through it. I left it for another hour and it warmed right up like its supposed to. Then I gave it back to him and then pop. Makes no sense.
So when I got it back, the input sensitivity was set to 3/4 the way up and his deck was set to +5dB on the subwoofer output. He also has a 5.0V MAX output on his deck. Apparently this can blow a Taramps amp up like nothing. I'm trying to verify this with Taramps but the guy I'm speaking to is having a hard time understanding english
. This amp's input sensitivity is listed as 220mV or something crazy. I just find it hard to believe that these don't have a range or something. But when reading posts online, they all say that these amps don't like + any dB on the head units and they live in the 2.0V out and less range.I for one do not believe that my workmanship is what caused his amp failure especially when it worked flawlessly on my bench. I had music playing to it for about an HR and my dummy loads were screaming hot. But how can just hooking it up to a deck and then turning it on, getting the fans running then smelling smoke make any sense or happen? His system voltage is 14.4V dead on and his battery bank is large. Also his final impedance measured with a DMM is exactly 1.0 ohms. Baffling. Tomorrow I'm going to pop fresh parts in and continue investigating this thing.
Large amps have a problem with intermittently shorted inductors.
If the amp has no rail regulation, a higher B+ voltage will increase the rail and make a borderline inductor, short.
No amp should fail, with regard to it's signal, no matter the input or the settings on the head unit if it's being driven into a safe load.
If the amp has no rail regulation, a higher B+ voltage will increase the rail and make a borderline inductor, short.
No amp should fail, with regard to it's signal, no matter the input or the settings on the head unit if it's being driven into a safe load.
Exactly what I thought Perry. I thought how can an input signal alone cause an amp blowout. Doesn't make sense. If the input voltage is at MAX and the gain on the amp is set high then the amp just makes it's voltage increase sooner. The amp would clip then the user would turn something down.
When you read posts online about Taramps though, people will swear that when they keep their head unit preouts set to 2.0V or less they have better luck. I'm not sure if it's a mental thing or what
My question is why would an amp blow if the impedance is proper, B+ voltage is proper, and it's idling without music? Also this guy has a reputation for blowing up amps. He had this amp a month before it went boom. He has also blown up Digital Designs as well. I'm just wondering if this guy is telling me stories and setting his impedance lower and basing everything on box rise....
When you read posts online about Taramps though, people will swear that when they keep their head unit preouts set to 2.0V or less they have better luck. I'm not sure if it's a mental thing or what
My question is why would an amp blow if the impedance is proper, B+ voltage is proper, and it's idling without music? Also this guy has a reputation for blowing up amps. He had this amp a month before it went boom. He has also blown up Digital Designs as well. I'm just wondering if this guy is telling me stories and setting his impedance lower and basing everything on box rise....
Ok so I fired this amp up today after replacing all the parts that have blown. I put my DMM in DC and measure with my negative probe to the anode and the positive probe to the cathode of all of the gate zener diodes. All diodes read 5.8V across them with the exception of FET2 and FET19. They both read 5.20V. Also when i measure across DZ3 I get 12.14V and when I measure across DZ1 I get 10.56V. Taramps says not to worry about this but why such a difference. The difference is showing up on the side that doesn’t blow.
Also when I put the thermal imager on the board there are two resistors that glow very bright. They are R122 and R115. They sit in the output section near the rail caps. The board is drawing its recommended 5.1A so I’m now wondering if this guy isn’t doing something to blow this amp.
Also when I put the thermal imager on the board there are two resistors that glow very bright. They are R122 and R115. They sit in the output section near the rail caps. The board is drawing its recommended 5.1A so I’m now wondering if this guy isn’t doing something to blow this amp.
I did that and no change in current draw.
It appears that R115, R122, and R108 are in series with pin 14 of the MCU. Those resistors are connected to the high side rail. So yes they should probably get hot.
With my scope, I connect my ground to main ground, and check all the gates. All high sides I get 12.1V and all low sides I get 8.5V. Since the negative circuit keeps blowing and both sides really match up quite well I have to assume that it's something the dude is doing when he puts his amp into his truck and wires it to the rest of the system.
I'm going to put back together and test again and see where this goes.
garnerm: Amp at idle and at 14.4V, how much current are you drawing? I checked my pin 15 with my scope and I'm getting the same as you - around 150V or so - low side. Low side drives the high side, right?
Perry: What do you make of the input sensitivity spec saying it's 220mV and not a range like usual? Usually they'll say from 5.0V or so down to 220mV. It's almost like home audio where the CD player has 250mV out and the receiver would be sensitive to 250mV. In that case wouldn't the volume be a volume and not a gain? Seems like this Taramps stuff is configured the same way as home audio
It appears that R115, R122, and R108 are in series with pin 14 of the MCU. Those resistors are connected to the high side rail. So yes they should probably get hot.
With my scope, I connect my ground to main ground, and check all the gates. All high sides I get 12.1V and all low sides I get 8.5V. Since the negative circuit keeps blowing and both sides really match up quite well I have to assume that it's something the dude is doing when he puts his amp into his truck and wires it to the rest of the system.
I'm going to put back together and test again and see where this goes.
garnerm: Amp at idle and at 14.4V, how much current are you drawing? I checked my pin 15 with my scope and I'm getting the same as you - around 150V or so - low side. Low side drives the high side, right?
Perry: What do you make of the input sensitivity spec saying it's 220mV and not a range like usual? Usually they'll say from 5.0V or so down to 220mV. It's almost like home audio where the CD player has 250mV out and the receiver would be sensitive to 250mV. In that case wouldn't the volume be a volume and not a gain? Seems like this Taramps stuff is configured the same way as home audio
I was powering them at 14.2 and it was pulling 3 and some change but I just gave the amps back to the guy early so I can't get you that exact number but no where close to 5 amps. That could just be my cheap eBay special of a power supply I dont really count on it for an exact number but it seems to be accurate within .25 amps from other tests.
How did you test the amp before giving it back? Do you have a power supply and dummy loads or speakers? I only ask because I'm just wondering if my tests are enough.
Also jentronics.ns.ca is where I got my power supply from. It's pretty decent and since you're American it would be cheaper for you to buy from Canada since the exchange rate favors it. I bought a Circuit-Test PSC-6632 bench top power supply. It does from 1-32V and from 0-20A. It has served me well.
Also jentronics.ns.ca is where I got my power supply from. It's pretty decent and since you're American it would be cheaper for you to buy from Canada since the exchange rate favors it. I bought a Circuit-Test PSC-6632 bench top power supply. It does from 1-32V and from 0-20A. It has served me well.
The guy owns an audio shop here I let him do the stress test after I just give a light test with a sub here. I'm pretty new to this I'm definitely still learning so I'm sure whatever you are doing is better than me. I've just gotten lucky and no one works on amps in about 200 mile radius of me so all the local shops give me stuff to learn on for free/pay me for successful repairs.
If you haven't already, I strongly recommend that you follow the links on Perry Babin's signature in these posts. He has a ton of very useful information and it's all very detailed. I've purchased his amp repair tutorial quite a while back, and I'm still reading it. In fact, I've recently purchased a small laptop so I can stick this tutorial right in my face until I get it all 100%. He has taken years of tried, tested, and proven techniques and compiled them into a very easy to understand tutorial.
I know that what I'm doing lines up with what Perry teaches. I've been messing with electronics for about 25 years. I've never gotten into this kind of amp repair before as there is really no "course" out there. You'd have to get into engineering in order to do it for real. Amps that I have repaired were smaller amps that had bad solder joints, broken emitter resistor legs, and simple repairs. More complex repairs I never touched, until now.
I know that what I'm doing lines up with what Perry teaches. I've been messing with electronics for about 25 years. I've never gotten into this kind of amp repair before as there is really no "course" out there. You'd have to get into engineering in order to do it for real. Amps that I have repaired were smaller amps that had bad solder joints, broken emitter resistor legs, and simple repairs. More complex repairs I never touched, until now.
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