I'm living in a rental house now which has rather "interesting" wiring...someone retrofitted all the old 2-prong AC outlets with 3 prong plugs, but of course none of them actually have a ground, so I get really bad hum in a lot of my audio equipment. To remedy this with the AM transmitter, I used a 3 prong to 2 prong adapter plug to isolate the transmitter from the non-existent ground. This worked fine for about a day, but I got home today and found that the fuse had blown in the transmitter. I did leave it on for 24+ hours by accident, but I've done that before without any issues. Is there something else I need to do to make this device work on my current wiring? Before you all say it, as much as I would like to, I do not have the ability to rewire the whole house (it's not my house anyway, I'm just renting!), so that is out of the question.

EDIT: I should note that my transmitter is built in a plastic box, so I'm pretty sure all the chassis grounds are tied to AC ground at some point in the circuit. However, it's been 2 years since I built it, so I could be wrong.

Thanks,
Dan

I've found antenna placement to be paramount... On my most used transmitter with ant placed along the baseboard, hum was so bad it wasn't useable but draped across the double window curtain rod that's behind it, hum is almost nonexistent... This house has grounded outlets but cord on Tx is a two wire non polarized type....

If the above doesn't help, you could try grounding it to a cold water pipe... Just be careful it doesn't have any current leakage from something possibly miswired or defective, remember something blew the fuse...

Radio Shack sells a RCA type stereo cable to eliminate ground loop hum, but reviews are mixed and it's $20 so would be a gamble...


Tom

The lack of an earth connection shouldn't have anything to do with blown fuses unless there was a lightning strike (in which case you'd also need sufficiently rated surge protectors).

Thanks guys. I replaced the fuse and so far, so good, so maybe it was just a bad fuse, or there was a surge? It's connected to a power strip with most of our other AV equipment connected so maybe something weird happened on the line, who knows.

Fuses are extremely simple devices so, while theoretically possible, it's unlikely one was defective. What type, fast/slow blow, and what amperage was/is it?

A power line surge is more likely but, even there, it's not clear how that would blow a fuse (since there is no earth connection to clamp the surge to) without some other damage, like over-voltaging filter caps, which would be the actual cause of the fuse blow, but you say it’s okay now.

The only other thing I can think of, off hand, is some kind of surge being cross coupled through the common, but unearthed, chassis ground that essentially provided a path from one device's hot to the other's neutral but it's difficult to say exactly how without knowing the surge protection and chassis connection of the various devices.

I'd suggest looking into it and seeing if the electrical wiring is to code. If not you can press the issue and I bet the owner of the house will be more than happy to change it out. Ungrounded outlets can be very dangerous if a device with a ground connection faults to the metal case which puts line voltage on the device's case and could hurt or possibly kill whoever touches it.