[SOLVED] Stereo volume problems

[Catorb]

Hi
I recently got an Optonica SA 5205, and hooked up my bose 4.2 speakers to test if it works properly. It does, except that the volume is so quiet I can barely hear at 100%. I don't know a whole lot about audio equipment so im completely stumped. If anyone knows anything it'd be appreciated.

 

[boju]

What are you playing through the amp?

 

[Catorb]

What are you playing through the amp?

I've tried AM radio stations the stereo can pick up, and I've also tried plugging in an RCA to 3.5mm adapter to my phone. Both were the same volume.

 

[boju]

Seems like there could be something wrong with the amplifier. Might be capacitor or fuse. An electronic repairer should be able to help.

Interesting video. Might not be your issue but worth a look.

 

[mortemas]

How about the headphone output? If that works ok then the problem might be isolated to the output amp section. Some amps have a preamp output on the back, usually with a jumper installed that patches it right back into the unit. You can test the preamp circuit by patching it to another system’s input. And inputting a signal into the preamp return (Marantz calls it Main In) will test the output amp circuit. In both cases, keep the volume levels all the way down and ease into it after patching so you don’t blow something.

You can also try this: exercise all the controls. Pushbutton switches, selector switches, pots, the jumper connection mentioned above if it has one. This will burnish the contacts and renew any bad connections due to oxidation. So to do this you would power off the unit and repeatedly push the pushbuttons in and out, twist the pots full range back and forth, turn selector switches to all selections back and forth. etc. Do this for 30 seconds or so for each control. You could also pick up some contact cleaner like DeOxit Gold, but use it sparingly and don’t use it on the pots - it could dilute the grease on the shaft, which offers that satisfying resistance when you turn the knob. You really need to take the cover off and get inside the unit to use contact cleaner properly. You don’t want that spray getting everywhere and causing a mess inside.