AC Inlet Filter Suggestions, Aguilar DB750/DB751

[GoldtoneWorkshop]

Hello everyone,

I've had several Aguilar DB750 and DB751's in the shop recently and they all had a similar failure point. The AC inlet receptacle in these models has internal capacitors for line filtering and the filters have stopped passing AC to the mains switch. I'm not sure if the problem is tied to misuse, as these amps all live a hard life for a local backline company. I recently replaced one of the in line filters with the same model and the amplifier came back within a few weeks with the exact same failure in the inlet jack.

The amp is using a TE Corcom 15SRB1-Z filter. Is there another suitable line filter that you all have had success with in the past and could recommend?

[The Dude]

Odd. This makes no sense. The filters go, one each, from hot and neutral to ground. The caps don't pass AC to the mains switch. The schematic is right on the switch. I don't see how the inlet could "stop passing AC", unless it was a connection issue. If the caps stopped "capping", it shouldn't effect power getting to the unit. If the caps shorted, you'd be blowing a mains fuse. If you check continuity from the pins that go directly to the IEC plug to the pins on the back of the receptacle, do any show open or shorted?

[GoldtoneWorkshop]

I agree it's an odd fail state. Two of the pins are shorts and one of them is open circuit when measured the way you described. measuring the caps, one of them is reading the 3300pF as listed in the datasheet and the other is reading 6pF

[The Dude]

Obviously, if one of the pins shows no continuity from front to back (I think that's what you are describing?), there is a connection issue within the connector. If you are having multiple issues with these connectors, I'd just get a plain old IEC connector without line filtering and solder a couple of caps on the back of it.

[GoldtoneWorkshop]

Yeah there was no continuity between the front and the back. I used a regular IEC connector to get the amps up and running again.

[The Dude]

You probably don't need the caps. They are just RFI filtering. If you have noise problems, you could add them.

[Helmholtz]

If you add caps, make sure they are "Y" rated types according to safety regulations.

[Mick Bailey]

Have you opened up a defective unit to identify how its failing?

[GoldtoneWorkshop]

Yes! It looks like the bond wire going from one terminal to the other on the open side was broken. Not sure if it took too much current and opened up or what. I might try to use a dremel to get into the other defective one a bit cleaner.

[Jon Snell]

I would fit an IEC filter that has a traceable specification for reliability and safety, not a cheap junky Chinesium one.
I get many failures due to poor cuurent and voltage ratings of manufacturer fitted Chinese filters.
I use; https://uk.rs-online.com/web/p/iec-filters/2780324?gb=a


https://uk.rs-online.com/web/p/iec-filters/7084030

Not expensive and reliable.

Don't forget, the bonded earth MUST be crimped, not soldered.

[Mick Bailey]

The RS pro filter is Chinese. The Schaffner can be Chinese if the country of manufacture code on the label is 88.