Re: Vox mini 3 amp

I checked the aux in and it is slightly distorted when I have the MP3 player output volume higher. I guess it wasn't as noticeable when it was lower. The guitar input though is very noticeably distorted when it should be clean (btq clean or line). I guess what still confuses me why I have any sound. It's almost as if the gain stage is bad. When the gain is really low and the master volume is down, it's almost clean. Then again, maybe it's just too quiet to hear the breakup.

Re: Vox mini 3 amp

Yeah, the problem is still there even with batteries. Any other thoughts on diagnostics? Aux in with a MP3 player sounds clean, as does headphones with the guitar input. The mic input is buzzy like the guitar input. If your daughter board replacement chip isn't too hard of an install and is reasonably price to send across the pond, I'd be willing to give that a shot. Otherwise, I may end up with lots of spare parts to salvage to build another ruby or chime/punch amp and maybe install a 6 inch driver in the cabinet for better tone. PM me with details if you want...

Re: Vox mini 3 amp

I did measure it wrong the first time. This time I'm taking ground from the master volume potentiometer and do get 5V from ic9 and 2.5V from each speaker lead. I was mistakenly using ground from the power switch. Thanks for bearing with me.

Re: Vox mini 3 amp

Hi midibob,

I hope I checked it right. I'm a bit if a novice with a circuit so small and complex. I got over 5v at pin 3 on ic9 and about 9v at the speaker leads. That makes sense since I do get sound. The sound is just buzzy in a bad way, especially on BTQ Clean which was so clean before. It almost sounds like a capacitor is not working to filter out the noise. Are there other tests I could check? My experience is limited (built some small simple circuits like ruby, little gem, and punch amps), but I'm willing to learn.

Thanks,
...

Re: Vox mini 3 amp

Hi midibob,

I think my mini 3 is starting to go, too, but isn't completely blown since I still get a badly distorted sound out of my speaker. I tested the speaker alone with another amp and it's fine. The output from the headphone output is also normal. Since the output chip is completely blown, my resistances are okay. Do you think it could still be the chip or did I blow something else?

Thanks,
Microamp