Batboard

Since Motorola discontinued selling the Maxtrac Detailed Service Manual part number 688010102W84 it been difficult to troubleshoot this slightly ill Maxtrac. This is a Maxtrac 40 Watt 2 channel UHF unit that has great RX and TX. The only problem is that the TX audio is very low. I tried a known good working front end and its the same. Tranmit audio is present but very low. Even tried several mics including a Motorola base microphone. There are some resistors in the circuit but withou a schematic or service manual its very hard to trace anything. Any suggestions would be greatly appreciated.

You will have to get into the radio service menu and adjust the microphone properties with RSS as there are no internal adjustments for deviation or mic gain inside the radio.

About the only adjustment is one for squelch, and possibly reference modulation, that's it.

The RSS does not show any option for increasing the transmit audio. I have ordered the upgrade resisters from Motorola, maybe that will do it but again without a schematic or repair manual its difficult. Thank you for your response.

Hello :
Not saying that some components might not be at fault but id first remove the logic bd and clean the feed through interconect pins on the logic bd and also clean the contact sockets and reassemble.
Take close look with an ohm meter to confirm your not leaking though to chassis or components on the pins.
Ive seen wierd things unexplainable happen to maxtracs with dirty interconect feed throgh pins.

Satelite

Yeah, cleaning the pins would be a good start.. the maxtrac ones don't have feedthru caps built in like the radius connectors so they don't suffer from the problem of the caps breaking, but they can become oxidized and develop high resistance.

What's the history on the radio, did you receive it in it's present state, or was it working okay and then the mod quit?

Is the PL mod okay, or is it low too?

Have you looked at the DC voltage on MIC HI, and have you looked at MIC HI with a scope? If so, what DC voltage and/or audio level did you find?