PM1500 no modulation or PL encode

[arlojanis]

I have a VHF PM1500 P25 that worked normal one day and had no mic modulation or PL encode the next day. Programming and alignment look OK.
Anyone know a fix? If I sent to depot, do I need to send the control head too?

[JohnDo]

I have repaired a XTL2500 with this same issue

You have to inject a tone into the mic port and trace the audio path with a scope to identify the faulty component, In my case it was a faulty mux

DSM describes a procedure for this