Mistyped or testing me?
There is sometimes (rarely) a problem with an incomplete loading of the banks but it's generally OK.
There is sometimes (rarely) a problem with an incomplete loading of the banks but it's generally OK.
LoL!! Nooooo! Total brain fade on my part. And thank you for the help it is greatly appreciated.
So fitted the 4 optocouplers and ran into another issue. U407 and the optocoupler next to it suddenly dropped voltage between pins 5-8.
Pin 5 on both remains steady at 21.2v and pin 8 is only 29v. Also the big resistor that's buried in silicon is getting pretty darn toasty. Looks like it is being fed 126.4v relative to main ground and out putting 29.3v. Out of circuit resistance reads 9150ohms so I am guessing this side of the optocoupler supply is relatively good.
Upon further digging it looks like the diode at D401 is toasty and reads 18ohms in both directions and 0.006v on diode setting in both directions out of circuit. So ordering that one. Also found D405 was bad and replaced it.
Any other suggestions on parts in the circuit for those optocouplers?
D401 is an 18v, 1.5w zener diode part number SZ1SMA5931BT3G?
So fitted the 4 optocouplers and ran into another issue. U407 and the optocoupler next to it suddenly dropped voltage between pins 5-8.
Pin 5 on both remains steady at 21.2v and pin 8 is only 29v. Also the big resistor that's buried in silicon is getting pretty darn toasty. Looks like it is being fed 126.4v relative to main ground and out putting 29.3v. Out of circuit resistance reads 9150ohms so I am guessing this side of the optocoupler supply is relatively good.
Upon further digging it looks like the diode at D401 is toasty and reads 18ohms in both directions and 0.006v on diode setting in both directions out of circuit. So ordering that one. Also found D405 was bad and replaced it.
Any other suggestions on parts in the circuit for those optocouplers?
D401 is an 18v, 1.5w zener diode part number SZ1SMA5931BT3G?
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The 10k resistor is connected between the higher_than_rail voltage source and the cathode of D401. The anode of D401 is connected to the source of the high-side output FETs so it's swinging from rail to rail. The low-side of the 10k resistor follows the diode so it's going to get very hot.
Do not power the amp up without D401 in place.
Do you have an 18v Zener (with leads) that you can install in its place?
That's the diode number I get as well.
Do not power the amp up without D401 in place.
Do you have an 18v Zener (with leads) that you can install in its place?
That's the diode number I get as well.
I don't. Im not home now, but one of my other amps, a sundown sfb5000, has zener diodes inparallel with the output gate resistors. IIRC they are 18v but I'm unsure of their current capacity.
Update. Swapped in the new zener, got beautiful square waves on all gates and of course all optocouplers have appropriate voltages!!
Fitted 4 of the old output fets and tested it out! IT LIVES!!!
Then fitted the 064N fets on the power supply and fitted new 30N50s, cleaned up the small SMD capacitor pads, and fitted new caps as well.
60min of testing on music later and I'm getting some strange behavior. (It plays the music great but....)
I am getting a weird, slow fluttering of the cone of my test sub at about 1 to 3hz. This full extension, fluttering, comes and goes and sort of follows the rhythm of the music being fed. Subsonic filter doesn't to seem to have any effect on it. Thoughts?
Fitted 4 of the old output fets and tested it out! IT LIVES!!!
Then fitted the 064N fets on the power supply and fitted new 30N50s, cleaned up the small SMD capacitor pads, and fitted new caps as well.
60min of testing on music later and I'm getting some strange behavior. (It plays the music great but....)
I am getting a weird, slow fluttering of the cone of my test sub at about 1 to 3hz. This full extension, fluttering, comes and goes and sort of follows the rhythm of the music being fed. Subsonic filter doesn't to seem to have any effect on it. Thoughts?
Does it do this with no RCAs plugged into the amp?
Does it do this with the preamp board bypassed?
Does it do this with the preamp board bypassed?