That helped but I'm still getting 38v dc on the gates, high rail on the drain, and 20v dc on the source.
Could that inductor be faulty? It read 0.05mH in my reader with 1ohm resistancd
Could that inductor be faulty? It read 0.05mH in my reader with 1ohm resistancd
The low-side opto drives from the negative rail. The jumper keeps the gate-source voltage at 0v and both terminals at the negative rail.
The high-side opto drives from the source of the high-side output. With the jumper across the output terminals and the high-side opto jumped, the gate-source voltage should be 0v and at 0v referenced to ground.
You should read 0 ohms from the high-side source (and low-side drain) to the positive speaker terminal.
The high-side opto drives from the source of the high-side output. With the jumper across the output terminals and the high-side opto jumped, the gate-source voltage should be 0v and at 0v referenced to ground.
You should read 0 ohms from the high-side source (and low-side drain) to the positive speaker terminal.
I'm missing something here. (High side source and low side drain both show 0 ohms to the positive speaker terminal.)
On the optocoupers I jumped pin 5 to 6 and that's it. I have a 2ohm sub wired to the speaker terminals.
Using the amplifier's main ground my DMM was reading 38v on high side gates and 20v on high side sources.
Before your last reply I was thinking this might have something to do with the optocouplers' power supply so I removed the jumpers and retested.
High side gate-to-source voltage is zero but both the gate and the source show 19.x volts relative to main ground.
On the optocoupers I jumped pin 5 to 6 and that's it. I have a 2ohm sub wired to the speaker terminals.
Using the amplifier's main ground my DMM was reading 38v on high side gates and 20v on high side sources.
Before your last reply I was thinking this might have something to do with the optocouplers' power supply so I removed the jumpers and retested.
High side gate-to-source voltage is zero but both the gate and the source show 19.x volts relative to main ground.
Yes I can visually see the trace on both high side optos and the left lowsided opto. Right side low opto I can't visually see a trace but my DMM reads 0 ohm between 6 and 7.
Ok i think its good now.
There's no voltage across the terminals with the sub connected properly. High side appear to be good. With my DMM, the gates are showing 1.0v dc relative to main ground. Source is 0.0v to main ground. When I measure Gate to drain voltage, it starts about 0.8v and begins climbing, which i thought was bizarre.
So retesting with my o-scope and it shows no significant voltage even at 1v divide. So i zoomed waay in on the voltage divide. And there is an extremely weak switching signal (which I assume it is inductively picking up form the power supply; same frequency of 27kHz.) Would this super weak signal fool my DMM into displaying a rising voltage?
There's no voltage across the terminals with the sub connected properly. High side appear to be good. With my DMM, the gates are showing 1.0v dc relative to main ground. Source is 0.0v to main ground. When I measure Gate to drain voltage, it starts about 0.8v and begins climbing, which i thought was bizarre.
So retesting with my o-scope and it shows no significant voltage even at 1v divide. So i zoomed waay in on the voltage divide. And there is an extremely weak switching signal (which I assume it is inductively picking up form the power supply; same frequency of 27kHz.) Would this super weak signal fool my DMM into displaying a rising voltage?
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Feeding 40hz sine into the RCAs, I get a beautiful 40hz square wave on the two interior optos' input. The two optos on the outside don't have any input.
The other terminals are grounded. They are wired in reverse to provide an inverted drive in one of the optos.
Confirm that the power supply for both optos are about 18-20v before reinstalling them. You can check the gate drive to both banks of outputs before reinstalling them.
Are you going to re-wind the bad inductor?
If only 1 or two windings broke at the board, you can extend them if you don't want to rewind it.
Confirm that the power supply for both optos are about 18-20v before reinstalling them. You can check the gate drive to both banks of outputs before reinstalling them.
Are you going to re-wind the bad inductor?
If only 1 or two windings broke at the board, you can extend them if you don't want to rewind it.
There was proper voltage to the optos so I installed them, also swapped the small cap for an appropriate cap and wham beautiful 40hz switching at all gates at power up.
I extended the inductor's leads as well, as they broke right at the main board.
Thank you for all the help!!
I extended the inductor's leads as well, as they broke right at the main board.
Thank you for all the help!!
Those inductors are a very common problem. Do something better than they did to prevent them from breaking off again.
I was thinking about that today while testing the amp with 4 total output fets in high and low side. (It works perfectly BTW 😀)
There's no way to zip tie them in place. Hot melt glue will simply melt given how warm the filter inductors get. MTX used a type of silicon which still allows movement especially when warm.
CA glue perhaps?
I could always entomb the inductors with silicon but I'm not sure that would prevent leg snapping and might make retaining heat an issue.
There's no way to zip tie them in place. Hot melt glue will simply melt given how warm the filter inductors get. MTX used a type of silicon which still allows movement especially when warm.
CA glue perhaps?
I could always entomb the inductors with silicon but I'm not sure that would prevent leg snapping and might make retaining heat an issue.
I use E6000 or GOOP. If the inductors are on circuit boards, sand all surfaces and use the adhesives mentioned previously. Get the adhesive up through the bottom windings and onto the core to prevent any movement between the body of the inductor and the board. The silicone they generally use allows too much movement as you stated.
Side note, CA glue is very irritating if you ever have to desolder anything that has the glue on it.
Side note, CA glue is very irritating if you ever have to desolder anything that has the glue on it.