OEM Moto Charger Hissing

[3-SAM-12]

Hi Gang,

Have a small problem with a Motorola HT750,1250 Charger (HTN900C) Just picked up this charger from the radio shop brand new, and placed my HT750 in it, after about 6 minutes it hisses, and will do this every 5-8 minutes. I also have a EX500 that I have placed in this charger and the above does not happen. The battery on the HT750 is an OEM HNN9008A NMHI. Any thoughts??


Chris

[Al]

You didn't say whether the noise is coming from the charger base or the wallwart PS. In either case, if the unit's brand new it's under warranty so the dealer where you bought it will replace it. It's not normal for these chargers to make any noise - likely what you're hearing if the noise source is in the base is the PWM switching regulator or an inductor in the regulator circuit.

[3-SAM-12]

Sound is comming from the base, also tried it in another charger, and does the samething, so I think its the battery, because any other radio I place in the chargers do not do it.

[chartofmaryland]

The hissing is in the cheap transformers used in the chargers taking on a heavy load when the high current request is demanded by the voltage control. This is also the case when the hiss goes away and comes back in cycle after the trickle green LED is on.

The hiss is dominant in the waris chargers, impress chargers and minitor chargers.


CoM