The FET's source terminal (leg 3) for the FET that you're probing the gate.
The small transformer in the photo you posted when you posted the photo of the FET that drains the rail caps.
The small transformer in the photo you posted when you posted the photo of the FET that drains the rail caps.
That didnt seem to make a difference. While I was looking for that signal I swear I seen 7v a couple times but I am not anymore.
Scope set to 10us, 5v/div, DC coupling?
What if you measure the AC or DC voltage across the gate/source with a multimeter?
Do you see a square wave on pins 8 and 11 of the TLx94 driver IC?
Do you have remote voltage applied?
What if you measure the AC or DC voltage across the gate/source with a multimeter?
Do you see a square wave on pins 8 and 11 of the TLx94 driver IC?
Do you have remote voltage applied?
Last edited:
I have 1.17vac across the gate and source, no dc. Whatever this is on 8 and 11 I cant really zoom on. Either way it is nothing I'm used to seeing. I rarely mess with ic,s as they are rarely used in the pieces I work on. Yes remote voltage is applied the protection light is lit.
Attachments
No ICs? That makes things harder.
With the same scope settings, don't you see a waveform on the PS FETs with the scope ground connected to the source terminal of the PS FETs?
With the same scope settings, don't you see a waveform on the PS FETs with the scope ground connected to the source terminal of the PS FETs?
Yes I rarely mess with ic's. Except with pioneer tuner HA ic's. Usually if I need to test them I just replace them. I get the same exact waveform from gate to source where ps fets mount.
Why didn't you get the drive waveform previously?
Do you have a 0.01uf cap that you can install across the gate/source to see if you still have a good waveform?
You appear to have shop hours like I used to have.
In car audio, you have to learn ICs but they're not too difficult if you take the time to do it. Do it once and you're done.
Do you have a 0.01uf cap that you can install across the gate/source to see if you still have a good waveform?
You appear to have shop hours like I used to have.
In car audio, you have to learn ICs but they're not too difficult if you take the time to do it. Do it once and you're done.
I do have a .01uf cap I can toss in there. I know these 12v amps are way different and newer then I'm used to. Hey il never know if I dont ask and dive in.
Last edited:
+1 for the CRT based scope.
Was the fuse a 15 amp ATC or ATO?
What was the value of the gate resistor you used?
Was the fuse a 15 amp ATC or ATO?
What was the value of the gate resistor you used?
The gate resistor I used is a 1/4 watt 38.3ohm. I was using a 14 amp sfe fuse inline. It was just one I had laying around after blowing two atc fuses. I have thousands of fuses. Just not a ton of atc.
These will typically power up through a 15 amp ATC and I recommended that because glass fuses (which I thought you might use) blows quicker.
Using the highest power inline lamp, if you try to power up through it, does the lamp start to dim, as expected or steady full bright (as bright as it might get on 12v?
Do you have a large 1 or 2 ohm resistor that you could use as a limiter? What about multiple 4 or 8 ohm on parallel?
Why was one of the waveforms slightly lower amplitude?
The reason I ask about limiters is so you could pulse the remote to get the rail caps partially charged before inserting the fuse.
That's a fortune in fuses.
Using the highest power inline lamp, if you try to power up through it, does the lamp start to dim, as expected or steady full bright (as bright as it might get on 12v?
Do you have a large 1 or 2 ohm resistor that you could use as a limiter? What about multiple 4 or 8 ohm on parallel?
Why was one of the waveforms slightly lower amplitude?
The reason I ask about limiters is so you could pulse the remote to get the rail caps partially charged before inserting the fuse.
That's a fortune in fuses.
I am not on a dbt right now. The amp is wired directly to a 750cca truck battery. Without the ps fets in the amp it is drawing no current. When I tried to power it up with this battery and the fets installed I did use a 15amp atc fuse like you recommended. I blew two of them before I stopped trying. One of the wave forms wasn't lower amplitude, I changed the voltage trying to get a better view of it. I have a ton of resistors on hand but having a big one or two ohm is unlikely. I guess it depends on how large of a resistor your talking about.
Large enough to withstand the current flow and power dissipation if directly connected across 12v (as it might be if having the FETs installed results in a dead short).
Il have to dig around in the morning and see what I have. I doubt I have anything that big though.
I do have a huge dummy load I built but I just realized I have somthing better. A battery load tester. I measured resistance across the leads and it has no resistance when the button is held. Obviously it can dissipate the amperage as it was designed too.
