Nuvi 350: Loud buzzing from speaker

if the battery charger is defective, it would / could cause buzzing. Technically, the charger might be putting out AC instead of DC.

Thanks for that but it buzzes on two adapters as well as on the ac adapter which I have to use in home while trying to figure out what is going on with this unit:

If the buzzing is caused by something in the device itself, I would check for faulty capacitors.

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OK: We rarely use sound on this: I suppose I can just stick a plug in the earphone socket. Are there any more widespread consequences to leaky caps on a unit like this please? Would they prevent the unit charging its battery? I suspected that no one would think that a short in the battery would be causing the buzzing!

I have done it ONCE On a Rogers Cadet 111 amplifier but I cant imagine there can be any easy way to replace caps on a tiny circuit board like this? (I only dared to do it on the Rogers because they were exceptionally easy to identify, buy ones of similar values and solder on that 1960s circuit board)

The stability of the sound circuit could depend on the battery having a low impedance and acting like a capacitor. This would save on the need to have extra capacitors included in the design. Then if the battery has too much internal resistance this effect would be lost leading to parasitic oscillations - buzz. I hope this gives you some confidence that a new battery could cure the problem. But don't blame me if not...

Mike.

It's not nice to criticize when someone asks for help -- but you should have learned in school that a dead battery means that a device will just sort of lie there and do nothing.

Why the unit should work properly when being powered by the 5V from the USB cable, but otherwise produce a buzz, is not clear. How does it work when being powered by your car's battery (that is, the plug-in cable)?

It's almost certainly not the battery. As you point out, it's difficult to replace SMDs. I would suggest sending it back to Garmin.

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SB

No, as I said, this problem occurs when plugged into DC power, different DC power, and AC power. Only slightly baffled why buzzing disappears completely when side USB port is plugged into computer but no one seems to have any ideas on this.

Really not sure what to do ACTIVELY about it as it does work fine, with new maps so long as you don't mind no sound and having to leave it plugged in all the time. Replacement of a numerous year old unit on Craigslist would cost a small amount of money compared to replacement with a refurb at Garmin AND any repair is likely to be quite intricate. Wouldn't mind replacing the battery at about ten bucks but am not sure that it would even WORK, not to mention get rid of sound issue. Theoretically if this unit is over 3-4 years old, the lithium battery may be dead AND if it hasnt been charged for some time, the voltage would have sunk to so low a level, - for a lengthy enough period of time that even if it weren't, it surely now is!

To recap: Leave plug in earpiece output to cut off speaker and await whole unit failure. Take out when sound actually needed. (look for similar unit on Craigslist for five bucks with dead battery and no accessories and see if my battery suddenly springs it to life!)

Sorry, FWIW, for the benefit of onlookers who dont know this unit, it has TWO usb ports: One for power in the back and a separate data-only port to plug it into the computer at the side. It buzzes until the side usb port is connected to a computer, - it gives a splash-screen and then as soon as the connection is recognised, the buzzing stops.

Only caught a few of the posts in this thread, so if I'm too far off base I apologise. Many of the cheap power supplies are half-wave (rectified one way only instead of through a bridge. They rely on a capacitor to modify the intermittent "DC" to a (sort of) constant voltage. It may be that the design of the Nuvi has this capacitor within the body of the unit, so that if this capacitor has gone down, the smoothing will be non- existent. If the buzz is mains frequency this would support the hypothesis. If you can find a good quality full wave power supply, and this eliminates or markedly reduces the buzz, it would (almost) prove the case.

Keith

Surely all small low-voltage power supplies these days are switched-mode with a tiny high-frequency transformer. This transformer provides isolation of output vs input circuits, allowing use of a bridge. Using a bridge rectifier at the supply input reduces the size of the smoothing capacitor needed there to keep the switching running throughout the AC cycle. Virtually no mains-frequency should get to the DC output. And if it did it is usually described as a hum (even for US 60Hz) rather than a "buzz"...

Mike.

On Thu, 9 Feb 2012 10:12:31 -0800 (PST), Austen put finger to keyboard and composed:

I'm confused.

According to the following guide, one of the three options for charging the battery is to "connect the AC adapter to a wall outlet and the mini-USB connector on the side of the nuvi".

A second way is to "connect the USB cable to the nuvi and your computer".

The guide does not mention two USB ports.

- Franc Zabkar

There's a USB port on the GPS unit and there's a USB port on the car dock. When you use the GPS in the car, the power cord plugs into the dock, and the dock has some pins that engage pads on the unit to transfer power to it.

There's a USB port on the GPS unit and there's a USB port on the car dock. When you use the GPS in the car, the power cord plugs into the dock, and the dock has some pins that engage pads on the unit to transfer power to it.

On Fri, 10 Feb 2012 14:50:05 -0800, "Scott W" put finger to keyboard and composed:

AIUI, the GPS can be powered and charged either via the side mini-USB connector or via the rear DC power socket (wherever that is).

If an adapter, either AC or DC, is plugged into the rear, then the unit buzzes. OTOH, if the mini-USB connector is used, then there is no buzzing. This suggests to me that, if two power sources are connected to the unit at the same time, then the side port takes precedence. It probably disables the rear port, which would explain why the buzzing goes away.

One thing still bothers me, though. The OP states that the AC adapter plugs into the rear port, yet you are saying that this is not a USB port. The guide, OTOH, refers to the AC adapter as a standard inclusion with the nuvi 350, so presumably it has a micro-USB plug (???).

One other thing that may be worth considering is the current draw. A computer's USB 2.0 port is current limited to 500mA, so this would place a limit on the charging current via the side port, at least when the GPS senses a USB host controller. AIUI, USB OTG (on the go) specifies a signalling system that enables a device to draw a greater current when it senses a charger. Maybe that could account for the difference in behaviour.

- Franc Zabkar