Batboard

Hello,
I am recieving a hissing sound on the recieve audio at low levels. It sounds similar to if the speaker has been blown. I have noticed this on other MTS2000 radios. Does any one have any suggestion?

Thanks,
Joe

If you have the volume turned down to its minimum level, the audio PA does not drive the speaker hard enough to get the 'punch' to clear up internally generated noise and overcome it as well, so a slight amount of hiss can be noted, but will probably disappear once the volume is turned up enough to overcome it as to no longer be noticed.

Not every radio has this occur as it depends on the audio circuits and how the audio is routed, and the filtering the audio has as well.

There should be an RSS setting to set the minimum audio level that the volume pot can control, and it is there so radio shops can set this to a level that will always make sure the person can hear the radio even when the volume control is turned all the way down, PD radio shops do this for the obvious reason...to prevent the officers from claiming they didn't hear a call on their portable, that's no longer an excuse that can be made.

As for thhis being a service problem, I doubt you need to worry about it.

Where is the RSS setting?

have you got a cro ?
if you have put it on the audio amp chip.
the audio amp chip runs off the dc supply directly and can fail easily

it's a bad audio PA...

how much does it usually cost to replace the pa? Is this something easy done?

Joe

We have a price of the PA module for the GP300 at $432 Aussie dollars and for the PA transistor for the GP328 is $45. its easy to replace