620 relay

[jeffV]

what is the value on the zener diode?

 

[avionic]

HZ-12C ---- 13.2 - 13.7 vdc @ 500mw



This is and exact replacement
http://www.mouser.com/ProductDetail/Nexperia/NZX14A133/?qs=mSipnS5lFm9sKxfTKivFxA==

 

[avionic]

The schematic says HZ-120 --typo !! The parts list calls for a HZ-12C.

 

[jeffV]

all the listed caps are replaced, but had to order the zener..I will keep you updated.

 

[avionic]

all the listed caps are replaced, but had to order the zener..I will keep you updated.

Did you try it after replacing the caps ?

 

[jeffV]

I have not tried it because the zener diode is removed from the circuit.

 

[jeffV]

Zener is installed, still seems to be no power getting to the relay, it still does not click over. no sound.

What now?

 

[avionic]

Remeasure the voltages around TR808.

 

[jeffV]

E. 10mv
C. 22v
B. 39 mv

 

[avionic]

Page 10 of the service manual. Measure the voltage on Test points 1,2,3 & 4. With your black test lead connected to chassis ground.Probe each test point with your red test lead.

 

[jeffV]

TP1. 15.4 mv
TP2. 30.4 mv
TP3. 40.3 V
TP4. 40.3 V

 

[avionic]

TP3. 40.3 V
TP4. 40.3 V

Big problem... Possibly a shorted output transistor or two. Need to test the right channels output transistors.

 

[jeffV]

Big problem... Possibly a shorted output transistor or two. Need to test the right channels output transistors.

what is the best way to do that? They are brand new by the way..

 

[avionic]

Ideally. Remove and ohms/diode test out of circuit.

 

[jeffV]

ok, will test right after dinner.

 

[avionic]

That 40.3 volts is why the relay is not "setting" . The protect circuit is working like its suppose to. If any DC voltage is detected at the amplifiers output. The circuit will not energize the relay and allow that DC voltage to get to your speakers.

 

[jeffV]

what numbers am I looking for?
ohm, volts?

 

[avionic]

Shorted junctions C - E, B-C and B-E.

 

[avionic]

 

[avionic]

ohm, volts?

Ohms or diode test