Er, no, but the MB3756 that is the power supply Regulator that delivers 8 volts can do this if the mic is not wired right. Thermal shutdown.
Only one pin needs to be grounded to make the radio TX - if you "ground" RX - DON'T - that is just the speaker return it USES ground at Pin 3 - because it will short thru to pin 4 - while Pin 4 - GROUNDS Pin 5 - and OPENS Pin 3 - so 4 is "common" to 3 and 5 - while 2 is exclusive to pin 1.
- Yes, Pin 2 is also Ground, but will interfere with Audio signal.
- Be flexible - Pin 4 is true Board Ground, Audio Ground is filtered - so that is handled on the 4-Pin DONGLE side - 2 and 4 from 5-Pin are tied TOGETHER - on the 4-Pin plug side..
So ... Pin 5 isn't grounded - only to Pin 4 when in TX - that is for the MB3756 to toggle two lines - RX to TX and back again when done
Then, Pin 3 - is your speaker, yes, you can go right in there and measure from that pin on the panel, to the speaker cone and see 8 ohms across those terminals at the speaker. Pin 3 is live for the Audio line.so you can ground it and yodel for instant talkback.
So make sure Pin 3 routes to speaker, pin 4 to board ground FOIL ground like Battery Negative ground. That is different from CHASSIS or case / panel sides ground.
Which brings up another condition - is the radio "Strapped"?
Being that Case rear panel and Battery Negative are tied as one ground?
- IF so, please remove this ASAP
- - can Damage the MB3756
- - which needs to run mounted thru an INSULATOR onto it's back and tab of it so it stays ISOLATED from panel and case ground and only ground it sees is thru it's Pin 4 on the main PCB.
- Pins 3 and 5 ON THE MB3756 - use caps to control ripple and steady the regulation within it. If these are shorted - Look out!
On the 5 pin to 4 pin "dongles', the wiring scheme is like a Cobra/Uniden 4 pin
4-Pin Dongle side...
Pin 1 - Ground - Shorts to Pin 4 in RX, Shorts to
Pin 3 in TX
Pin 2 - AUDIO - Live in TX - some it is LIVE all the time.
Pin 3 - TX - Open in RX -
Shorts to Pin 1 in TX
Pin 4 - RX (Speaker Return -Speaker is live on this line) Shorts to Pin 1 In RX
5-Pin "Plug" side...
Pin 1 Audio - Live in TX - in some radios they want this shorted to Ground in RX (Pin 2)
Pin 2 grounds - so
ties the 5-pin mic's 4 and 2 together - Usually Shield
Pin 3 Speaker RX - Shorts to Pin 4 in RX, Opens in TX - breaks speaker connection.
Pin 4 Common SW - Shorts to Pin 3 in RX -
SHORTS to Pin 5 In TX
Pin 5 TX Mode - Open in RX, Shorts to Pin 4 in TX
So when doing the Dongle Conversion...