Desktop Microphone Fault

[BlueYonder]

Hi,

I have been trying to repair the single and multi-tone (3 tones) roger beep feature (known as Extended Transmission Signal (ETS) on the mic) on a newly acquired Astatic EchoMax 2000. I found that both relays (K1 and K2) were not switching at all, so I replaced both but the fault persists. With ETS enabled on the mic, the momentary and latching PTT buttons (SW1 and SW2 respectively) both fail to produce a single or the proper multi-tone after de-keying. So, no single tone at all but the multi-tone just about manages to produce a very rapid two or may be three tone beep before the transmit ends.

This seems to me to be possibly a timing issue as I can get both ETS single and multi tones tones to work perfectly if I pre-short out the Transmit (pin 3, JP2) of the the RJ12 connector to ground (Gnd, JP2), so that the transceiver is already in transmit before either PTT button is pressed.

I wonder if someone might be able to advise me on how the timing at the end of transmission is handled and the components involved? Perhaps a capacitor has drifted out of tolerance, which is causing the time allowed for the roger beep to be shortened?

Thanks!

BY

 

[Nigel Goodwin]

It's got a micro-processor in it (presumably it's a really old device?), so I would imagine all the timing, tone generation, etc. is all done inside that.