SX 450 no AM/FM

[micrometer]

I'm back to this SX 450 after a major medical issue. Let's just say I'm glad to be here so I'm able to work on this unit again.

I still have no sound or AM/FM deflection meter action on this receiver in AM/FM mode. AUX, Phono, Tape - Rec/Play all work as normal.


Here's my question; Which way would be better/easier to use so I can check the tuner function?


1. I acquired another working receiver (Sony STR-7025) with a good AM/FM tuner that can be hooked up to the SX 450 ( I don't know how to do this).
OR

2. I have a spare AWE-074 board without the selector switch. This was an eBay purchase that's supposed to be in working order. Could I connect only the tuner and power test points to see if this fixes the tuner problem?

Any suggestions/recommendations would be much appreciated.

https://audiokarma.org/forums/index.php?threads/sx-450-no-am-fm.980616/

Thanks,
Mike

 

[Pio1980]

First, voltages @ the tuner and IF/MPX. Then check for common mode tuner section problems.

 

[micrometer]

First, voltages @ the tuner and IF/MPX. Then check for common mode tuner section problems.

TP 2 - 35.37 vdc
TP 17 and 20 - 13.89 vdc

ic HA 1156 - all seem good except for 8 - very low (FM muting off)

TP 2 - 3.06 vdc
3 - 5.12 vdc
4 - 11.75 vdc
5 - 11.79
8 - .011
9 - 2.33
11 - 1.88
12 - 2.34
13 - 1.88
14 - 3.89

 

[Pio1980]

Have you the schematic?

 

[micrometer]

Have you the schematic?

Yes

 

[Pio1980]

Yes

It's in the other thread.