Got a hifonics zeus VIII here, big white surfboard huge amp.
Stuck in protect. the outputs, drivers, pre-drivers, and power supply mosfets test fine.
quick measurement seems pin 1 of the TL594 is high, nearly 12v. Which is higher than the negative side, so of course the power supply circuit is pinned into shutdown. It powers up this way, the SMPS never fires. ever.
So, i pulled pin1 to ground momentarily and the SMPS fired up and the amplifier began to produce sound for a little bit, then of course the rails ran up too high so the SGSD100 circuit cut off the rails to the output section. Once i let go of pin1, the rails started to settle down, once it fell past 60v, the amp played again until the caps discharged. So keeping pin1 low causes the amp to run, but of course its not regulating.
any ideas?
Stuck in protect. the outputs, drivers, pre-drivers, and power supply mosfets test fine.
quick measurement seems pin 1 of the TL594 is high, nearly 12v. Which is higher than the negative side, so of course the power supply circuit is pinned into shutdown. It powers up this way, the SMPS never fires. ever.
So, i pulled pin1 to ground momentarily and the SMPS fired up and the amplifier began to produce sound for a little bit, then of course the rails ran up too high so the SGSD100 circuit cut off the rails to the output section. Once i let go of pin1, the rails started to settle down, once it fell past 60v, the amp played again until the caps discharged. So keeping pin1 low causes the amp to run, but of course its not regulating.
any ideas?
It's not likely that pin 1 is used for regulation. Typically, pin 1 is connected to the positive rail. If it was being used for regulation, the voltage on that pin would be at 0v if the power supply was not producing output.
If pin 1 goes to an LM358 (possibly via a diode), it's possible that the LM358 has failed. Look at the voltage on its output pins and see if they agree with the voltage on its input pins. If it doesn't, replace it.
If pin 1 goes to an LM358 (possibly via a diode), it's possible that the LM358 has failed. Look at the voltage on its output pins and see if they agree with the voltage on its input pins. If it doesn't, replace it.
It may have multiple circuits feeding it. I've never seen an amp that uses the inputs for the regulation for anything else but I've never really studied the circuit in a series 8 Zeus.
I'm assuming that the 3 resistors don't also go to ground or a voltage reference.
Lift/desolder the resistors, one at a time to try to narrow down the fault.
I'm assuming that the 3 resistors don't also go to ground or a voltage reference.
Lift/desolder the resistors, one at a time to try to narrow down the fault.
Resistor 1 is at 4.2v Resistor 2 is at 4.6v and Resistor 3 is at 4.8V
Rechecked pin1 again, which is the other side of all the resistors, is 8.6v. Higher than the 5V reference. So, the error amp is true, so the SMPS dont run.
When first hit with power, they are all at 4.1v But Resistor 2 and 3 slowly climb and settle at 4.6v and 4.8v
Rechecked pin1 again, which is the other side of all the resistors, is 8.6v. Higher than the 5V reference. So, the error amp is true, so the SMPS dont run.
When first hit with power, they are all at 4.1v But Resistor 2 and 3 slowly climb and settle at 4.6v and 4.8v
Well, there is a jumper on the main board labled TEST. this guy is what connects pin 1 to ground, so not normally, no.
I found a diode thats also going to pin1, which goes into a transistor circuit. That diode is reading 9.3v on the oher side, so thats where the voltage is coming from
I found a diode thats also going to pin1, which goes into a transistor circuit. That diode is reading 9.3v on the oher side, so thats where the voltage is coming from
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I havent tried it yet. I talked to the designer Steve, he said that if I do anything to that circuit other than what its laid out, it will run open loop and blow the circuitry. I already ran it open loop so its past that point now.
I did tell him that it was 9.3v on the one side of the diode. He said there is something very wrong and he insisted he had to see it to figure it out. he couldn't recollect exactly on how that circuit operated. He explained how the loop circuit worked, but that was it.
Anyway, he said he did a 30% i think, over-wind on the transformer so I cant do open loop without blowing **** up. Ill try lifting the diode, but it may do more harm than good.
I guess the next order of business is to pull the driver and check all the capacitors for shorts/opens/leaks.
I did tell him that it was 9.3v on the one side of the diode. He said there is something very wrong and he insisted he had to see it to figure it out. he couldn't recollect exactly on how that circuit operated. He explained how the loop circuit worked, but that was it.
Anyway, he said he did a 30% i think, over-wind on the transformer so I cant do open loop without blowing **** up. Ill try lifting the diode, but it may do more harm than good.
I guess the next order of business is to pull the driver and check all the capacitors for shorts/opens/leaks.
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