PMMN4024A Speaker/Mic won't Tx on XPR6550

[WB0QQK]

I purchased two new (OEM) PMMN4024A speaker/microphones, one for my XYL's XPR6500
and the other for my XPR6550. Both mics work fine on the XPR6500.

I can hear receive audio on my XPR6550 through the speaker/mic, but cannot key the radio
with the speaker/mic. Received audio can be heard through the radio's internal speaker and
the speaker/mic at the same time.

With the speaker/mic installed, I can transmit and talk using the internal PTT and mic element
on the radio.

I tried keying the radio PTT simultaneously with the speaker/mic PTT and then talking into
the speaker/mic but no transmit audio would pass.

Compared all the settings between the two by opening their codeplugs, but can't find any
clue why the speaker/mic works with the 6500 and not the 6550.

Suggestions?

 

[Mars]

What firmware version is in the 6550?

 

[Fatboy]

Sounds like dirty contacts on the accessory connector of the 6550.... If so, I usually use a fine screw driver or dental pick to rough up the surface slightly. Dirty also means oxidized in this case, contacts should be shiny gold, not dull gold. FB

 

[WB0QQK]

CPS Version 10.0 (Build 510)
Firmware: R01.09.10
Code plug: 11.00.14

Same for the XPR6550 and 6500

 

[WB0QQK]

Thank you. Back in the day we used either the ink eraser from a ballpoint pen or a round typewriter eraser with a brush.
When the agency I worked for used HT220 ConvertaCom's, we used denatured alcohol to remove cigarette smoke residue
from the contacts. For the past twenty years or so, Scotch-Brite non-scratch scouring pads seem to work about the best.