Sansui QRX-7001 Phono problem

[Ed400]

Hi All,
I am working on a Sansui QRX-7001. It sounds amazing, and it is a great piece of equipment. I replaced the festoon lights with LEDs, calibrated AM/FM radio, output transistors bias and replaced a few components.
However, I have stumbled upon a phono issue. It is simply not producing a sound in any channel. I am not using the CD-4 so it is a direct connection from the phono pre-amp (module F2458) to the signal conditioner (module F-2425 via F-2423)

Now, I am focusing on the pre-amp module F-2458, as it is the prime suspect. I connected a 10mV 1000Hz signal generator on the phono input and didn't get any output on either pin 1 (left channel) or pin 10 (right channel).

Strangely the 6 transistors on the pre-amp seem to be working after measuring them with a transistor meter. However, there is no amplification. It is puzzling. The input voltage to pre-amp module measured at pins 05-06 is 35.9V...

I am about to replace the 3 transistors per channel (see screenshot), but before I do that, I just wanted to see if there is anybody out there with any better suggestions or advice.

Thanks,
Ed

 

[Ed400]

Well … it is embarrassing because it took me some time to realise that a previous technician put transistors in the pre-amp reversed ‍.. omg .. I should have checked that earlier. Anyhow all working now.