The saturation depending on the switching frequency, the characteristics of the core, how many turns you have in the primary winding, etc. It doesn't matter what you have in the secondary side of the transformer, except short circuit.
Without a schematic and making some guesses all 6 transformers are creating the main HV +/- rails. The aux winds on the on the bottom right making the +/- 15v sounds correct. The 12V above -HV rail voltage coming from an aux wind on the top right xformer also seems plausible. These are all very low current circuits and I don't think that's what's causing the failure of the switching fets. I can't see the output section in the vid so again guessing this is a 2092 based class D output or similar. If you suspect saturation from power and heat caused an inductance drop that could certainly take out a bank of fets. Weakest bank fails short and blows the main fuse saving the other 5. This heat can also damage the transformer core permanently and rewinding it won't fix the issue. Pull the transformers and check them with an LCR meter. Also anything that happens on the output. Blown open or shorted speaker will reflect back through the amp stage to the power supply. The amp stage is a control valve between the PS and the load. Usually the output filter caps will fry from an open load condition. Heat can ruin the ferrite core of the output inductor also. What I'm saying is it could be an issue in the output blowing the PS even though it all looks ok and functions at low power. My $.02. I could be totally off base. Good luck.
I don't think the toroidal is saturating. The low side switching currents will be at it's highest at idle, when the output stage is oscillating but no audio driving it. As you play audio it starts to modulate and the switching currents now become a factor of the duty cycle of that modulation. If the core were to saturate, it would be most likely occur at idle when the current is the highest. You can use a thermal camera and see how hot the core is at idle.
Thank you for this information. Most of these failures are "it failed at idle with no volume" usually after they did a demo or a pull. Some failures were just stopping at rest stops on trips. So I do believe there is a heat factor to this. I am a little confused though when you state the current is highest at idle. I am assuming you are saying the switching circuit currents (as in the drivers?) and not the primary power current. Now we are getting somewhere! I would love to be able to direct my customers in a direction to avoid this problem.
@@ellensburgamplifier Yes, gate drive currents will be its highest. But since the primary current of the transformer is just a multiple of the secondary, it would also mean the primary current would be at its highest as well for that toroidal. it's possible some kind of thermal runaway is happening. What usually needs replacing when it fails like this? When the PS FETs fail are the output FETs failing as well?
Post a picture to chatgpt and and pose your question. It'll give you more information than you would ever want. It will provide multiple links as references about the circuit design.
I wish I knew more about this. I actually have my old books from electronics school and plan on researching more on transformers. Isnt there a way to look for Transformer saturation with a scope? I remember seeing a video of someone using a scope to see the point of saturation.
Well sir you and bear vids are the only ones I watch I haven't noticed one thing he always says it's a generic design with that being said if you just noticed that you're having this problem being that it is an old design and battlefield tested I would say it's a lack of quality control substandard copper on something that is being pushed hard,, I'm also into reconing subwoofers and at one point in time f u audio and Patrick got a bad batch of voice coils that checked out when built but when put under strain failed
Thank you Frank. That is why I am digging into this. If I find something that could be causing this I will be able to forward the info to the powers to be for the OEM to change it.
As an inductor reaches it's saturation, it tends to lose inductance which will require more input power to sustain the output. It can also cause shifts in switching frequency that go beyond the range of it's control circuits. You could probably test this by watching the transistor behaviour and switching frequency under varying load conditions. But without the specific schematic and specs, it's hard to say for certain what goes wrong.
@anthonydavidson9379 I haven't even had a chance to check them out yet. I do know what caused them to blow tho. Speaker wires were touching. Hopefully it didn't get anything on the power side. He said there was no smoke and I can't see any physical damage on 1. Haven't had the back off of the other yet.
Not smart ? Shiiiiit ... you got this man....😂 your damn near genius in my book. 👍
Thank you! Faraday's Law was never my strong suit.
The saturation depending on the switching frequency, the characteristics of the core, how many turns you have in the primary winding, etc. It doesn't matter what you have in the secondary side of the transformer, except short circuit.
Without a schematic and making some guesses all 6 transformers are creating the main HV +/- rails. The aux winds on the on the bottom right making the +/- 15v sounds correct. The 12V above -HV rail voltage coming from an aux wind on the top right xformer also seems plausible. These are all very low current circuits and I don't think that's what's causing the failure of the switching fets. I can't see the output section in the vid so again guessing this is a 2092 based class D output or similar. If you suspect saturation from power and heat caused an inductance drop that could certainly take out a bank of fets. Weakest bank fails short and blows the main fuse saving the other 5. This heat can also damage the transformer core permanently and rewinding it won't fix the issue. Pull the transformers and check them with an LCR meter. Also anything that happens on the output. Blown open or shorted speaker will reflect back through the amp stage to the power supply. The amp stage is a control valve between the PS and the load. Usually the output filter caps will fry from an open load condition. Heat can ruin the ferrite core of the output inductor also. What I'm saying is it could be an issue in the output blowing the PS even though it all looks ok and functions at low power. My $.02. I could be totally off base. Good luck.
I don't think the toroidal is saturating. The low side switching currents will be at it's highest at idle, when the output stage is oscillating but no audio driving it. As you play audio it starts to modulate and the switching currents now become a factor of the duty cycle of that modulation.
If the core were to saturate, it would be most likely occur at idle when the current is the highest. You can use a thermal camera and see how hot the core is at idle.
Thank you for this information. Most of these failures are "it failed at idle with no volume" usually after they did a demo or a pull. Some failures were just stopping at rest stops on trips. So I do believe there is a heat factor to this. I am a little confused though when you state the current is highest at idle. I am assuming you are saying the switching circuit currents (as in the drivers?) and not the primary power current. Now we are getting somewhere! I would love to be able to direct my customers in a direction to avoid this problem.
@@ellensburgamplifier Yes, gate drive currents will be its highest. But since the primary current of the transformer is just a multiple of the secondary, it would also mean the primary current would be at its highest as well for that toroidal.
it's possible some kind of thermal runaway is happening.
What usually needs replacing when it fails like this? When the PS FETs fail are the output FETs failing as well?
Post a picture to chatgpt and and pose your question. It'll give you more information than you would ever want. It will provide multiple links as references about the circuit design.
Oh man something I will have to go look up. "ChatGPT" I have seen this but know nothing about it.
I wish I knew more about this. I actually have my old books from electronics school and plan on researching more on transformers. Isnt there a way to look for Transformer saturation with a scope? I remember seeing a video of someone using a scope to see the point of saturation.
I wish I knew more about this topic. It would help understand this particular failure.
Well sir you and bear vids are the only ones I watch I haven't noticed one thing he always says it's a generic design with that being said if you just noticed that you're having this problem being that it is an old design and battlefield tested I would say it's a lack of quality control substandard copper on something that is being pushed hard,, I'm also into reconing subwoofers and at one point in time f u audio and Patrick got a bad batch of voice coils that checked out when built but when put under strain failed
Thank you Frank. That is why I am digging into this. If I find something that could be causing this I will be able to forward the info to the powers to be for the OEM to change it.
To far above me tod.. 😂
As an inductor reaches it's saturation, it tends to lose inductance which will require more input power to sustain the output. It can also cause shifts in switching frequency that go beyond the range of it's control circuits.
You could probably test this by watching the transistor behaviour and switching frequency under varying load conditions.
But without the specific schematic and specs, it's hard to say for certain what goes wrong.
Which ruthless amp is this?
looks like the 8500
Yeah must be the 8500. I'm working g on 2 of the 10ks and they have 8 transformers.
@@hopskustomaudio how are the 10k going?
@@hopskustomaudio Ah that's where they went ;)
@anthonydavidson9379 I haven't even had a chance to check them out yet. I do know what caused them to blow tho. Speaker wires were touching. Hopefully it didn't get anything on the power side. He said there was no smoke and I can't see any physical damage on 1. Haven't had the back off of the other yet.
@barevids if he is open to suggestion ..
Sam is a great guy!