The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

I recently picked up a 29LTD classic YARD SALE' heres the problem'

UNIT TURNS ON JUST METER LIGHTS UP?
NO TX or RX , NO AUDIO OUT OF SPEAKER,NO LEDS LIGHTING UP?
THE RADIO IS VIRGIN NO ONE WAS IN IT EXCEPT ME SOLDERD A FEW CONNECTIONS BUT THAT WASN'T IT''THIS RADIO HAS THE UPD2816C PLL IN IT AND A REGULATOR ON THE SIDEOF THE RADIOS CHASSIS FRAME WITH 3 EXTENDED WIRES THAT COME FROM EDGE FRONT OF MAIN PCB BY THE CLEAR LED RIBBON.I ChECKED THE REG IT's GOOD ANd CHECKED TR23 REG IT'S GOOD AND VARIS DIODES ALL CHECK GOOD IS THE PLL CAUSING THIS? REMINDS YOU OF REGULATOR FAILURE KILLING POWER TO FRONT PANEL AND PLL ?

You really need a frequency counter to check for missing frequencies at some of the test points, this can guide you in the right direction most times.

The radio is not in PA mode ? that might cause similar symptoms.

My suspicion would be that it got reverse wired ? any signs of burns or heat around the protection diode ?

It may just be a simple case of bad solder joints, look over the entire PCB very carefully and resolder anything that looks even slightly imperfect.

I assume that you have tried another mic, in case the mic is not wired up correctly ?

Check D19 (5V Zener diode).

Check TR23, which is the main 8V regulator.

Check TR21 (8V TX switch).

TR23 doesnt read like a 8 volt regulator when radio is power up? But checks good on the fluke volt meter? I found tr21 tx switch to be OK?
but cannot find D19 Zenior diode where is it on PCB there is a d22 zenior besides tr23 but it's good ? The protection diode is good on DC input Again just the meter lights up no channel ch display tr 23 center pin is + and the othe legs are - ? this reads 13volts either way.it should be 8 one way 13v other but checks goodon vm? TR23 it's marked 2sc1226?

PS: I also tried a few good mics nogo with PA mode no audio some main voltage not getting to radio?

If you still need help, let us know the PCB number and also all the voltages of TR23 Base, Collector and Emitter and also the voltage at pin 11 of the PLL.

Rick.