JVC RX-450 receiver has high impedance outputs

[krispy]

Hello,

I'm trying to repair my JVC RX-450 receiver. After some troubleshooting I determined that while I can pass a signal to the output for the speakers and I can see up to a 14V signal, as soon as I connect an 8Ω speaker, the voltage drops to the millivolt range. I don't really know how to proceed from here so any help is appreciated.

 

[WHONOES]

Could simply be that the speaker selection switches are a bit oxidised and are presenting a high resistance to the speaker path. You could try cleaning the contacts and see if there is any difference after.

 

[Ylli]

Is the 14 volts unloaded an ac voltage (audio) or is it a DC voltage (offset)? When you power on the unit, do you hear the protection relay click after a few seconds?

 

[krispy]

Ylli: The 14V is ac. The relay does click. There was no 60Hz hum or static no matter how loud the volume was turned up.

Whonoes: Thank you for your suggestion. That wasn't it but it helped me solve the problem. Turns out the speaker selection switches (labeled '1' and '2') were the issue. I thought I should have both on (speaker 1 on and speaker 2 on). In reality, it seems that I'm supposed to set it as either '1 speaker' or '2 speakers.' Why there are two independent switches for a single setting instead of a slider switch between '1' and '2' I don't know. Anyway, it seems the problem is solved.

 

[Ylli]

Glad you found the issue. Many amps do not like loads heavier than 8 ohms. So when you switch in both speaker 1 and speaker 2, the speakers are connected in series instead of parallel. If you select speaker 2 and there is no speaker 2, then no complete circuit and no sound..

 

[WHONOES]

Pleased you got there without too much hassle.