Siltronics LA-550 " keying relay issues"

[Danzik]

Check the voltage at the lifted cathode of D6 to ground. Both AC and DC voltages. Then do the same at the anode. What do you see there?

15.55 volts AC on the cathode and the same at the anode, either side shows anything DC related

 

[SuperLid]

15.55 volts AC on the cathode and the same at the anode, either side shows anything DC rel

 

[SuperLid]

15.55 volts AC on the cathode and the same at the anode, either side shows anything DC related

Sounds like D6 is shorted. Do a diode test with DMM.

 

[Danzik]

I am also not sure that cap is good at c13 but I did not remove it when I did the test yet but the ohm meter never went to LO and it didn't climb nice and easy like a goo cap would

 

[SuperLid]

I am also not sure that cap is good at c13 but I did not remove it when I did the test yet but the ohm meter never went to LO and it didn't climb nice and easy like a goo cap would

You are not going to be able to test that cap without a LCR meter that tests at the rated voltage. I doubt you have one, so just check for a shorted cap.

 

[Danzik]

You are not going to be able to test that cap without a LCR meter that tests at the rated voltage. I doubt you have one, so just check for a shorted cap.

Looks like the diode is indeed shot !

 

[Danzik]

Sounds like D6 is shorted. Do a diode test with DMM.

All I have of diodes variety pack I have here are 1N4004 or 1N4007 would either of those be ok to use ?

 

[Danzik]

Sounds like D6 is shorted. Do a diode test with DMM.

I went ahead and used a 1N4004 and installed it now I have 19.3 volts at the cathode and no more buzzing from the power supply!

 

[Danzik]

I went ahead and used a 1N4004 and installed it now I have 19.3 volts at the cathode and no more buzzing from the power supply!

19.3 volts DC I meant

 

[Danzik]

I now also have 17 dc volts at the green and blue and white wire at the relay with the low or high power on and the power goes away when switched to bypass like it is supposed to ! However the relay still is not kicking in but I may need to test that zener diode and other stuff on the relay board I bet

 

[SuperLid]

I now also have 17 dc volts at the green and blue and white wire at the relay with the low or high power on and the power goes away when switched to bypass like it is supposed to ! However the relay still is not kicking in but I may need to test that zener diode and other stuff on the relay board I bet

Any 1N4000 series diode will work, so the 4004 is fine. Keep going through the circuit, now that you have a working power supply. There is no zener that I can see in the keying circuit. You have D5, a spike suppression diode across the relay coil, another 1N4000 rectifier and a switching diode D7.

 

[Danzik]

Any 1N4000 series diode will work, so the 4004 is fine. Keep going through the circuit, now that you have a working power supply. There is no zener that I can see in the keying circuit. You have D5, a spike suppression diode across the relay coil, another 1N4000 rectifier and a switching diode D7.

I replace the D5 on the keying relay board, now the relay kicks in but it kicks in right away when I switch to low or high power without keying the mic ??? ‍

 

[Danzik]

Any 1N4000 series diode will work, so the 4004 is fine. Keep going through the circuit, now that you have a working power supply. There is no zener that I can see in the keying circuit. You have D5, a spike suppression diode across the relay coil, another 1N4000 rectifier and a switching diode D7.

Isn't there a zener diode right there between the cap and large resistor ?

 

[SuperLid]

Isn't there a zener diode right there between the cap and large resistor ? View attachment 61077

Why do you call it a Zener? I believe that is D7. 1N914 NOT ZENER!

 

[Danzik]

Why do you call it a Zener? I believe that is D7. 1N914 NOT ZENER!

Ok, yeah I am not very good at identifying them it just looked like one that I saw online or this one I have here, i thought it looked like it