Help for a VOX solidstate

[allante666]

Its in my house, with my own guitars. It doesnt need anything plugged in to do it, it does it just sat on its own, no knocks, no bangs, no vibration it will start totally randomly. I know it would be advisable to put the speaker in another amp and another speaker in this one I just havent got round to it as I was hoping it would have done it by now.
Still, its a kind of nice amp with lots of bells and whistles to play with. Hasnt got the umph of a big Marshall I dont think despite having 22 'built in' amp models.
Anyway, Ill keep at it, one day it may take me by surprise. (thats the day when I will have lost the lead to my extension speaker and by the time i find it, it will have stopped!)

How about 'AnnMar'? you still watching? hows yours?

[J M Fahey]

Well, there's one GUARANTEED trick to make it fail: book an IMPORTANT gig, on which depends your future, carry it with no backup. Presto!!, it will start crackling on the opening bars.

[Chuckl]

I've had a few of those amps have the power output pot get cracked with those symptoms. I had to look very closely to see it was cracked, stick an ohm meter on it while flexing the carbon traces. Also there's a big black resistor on the edge of the board that breaks it's leads often, right at the circuit board. Sometime ya have to tug on the leads to find out. Good luck.

[allante666]

I've had a few of those amps have the power output pot get cracked with those symptoms. I had to look very closely to see it was cracked, stick an ohm meter on it while flexing the carbon traces. Also there's a big black resistor on the edge of the board that breaks it's leads often, right at the circuit board. Sometime ya have to tug on the leads to find out. Good luck.

Yes but the thing here is that it only does it through the speaker and not the headphone socket. Havent got the schem but im assuming all the headphone socket does is basically switch the speaker off and divert the signal. This would be after the power pot yes?

[Chuckl]

Actually the headphone is tapped off the line out circuit, pre power attenuation. I would also make sure the external speaker jack didn't had dirty switching contacts.

[J M Fahey]

Are you sure? Because you need not only "signal" but "power" to drive headphones.
Does it have a dedicated headphone power amp?
Preamp outs usually do not drive regular headphones by themselves.

[Chuckl]

I could be wrong, but that's how it looks on the schematic.

[J M Fahey]

Hi Chuck, not disagreeing with you, only curious.
Can you scan and post the schematic, or at least that part?.
They *should* have at least an LM386 or similar there.
NE5532 *can* barely drive phones, maybe you have those. Thanks.

[Chuckl]

I would love to but I don't have a scanner. I'd be more than happy to mail a hard copy though.

[J M Fahey]

Don't worry. Some day you will visit a cybercafe or office so equipped.
Thanks for trying.

[allante666]

Ive ruled out headphone and external speaker socket by hardwiring them. When I get a chance I will have a look at the power pot and also for the resistor you mention. Its just a curiosity thing now, Im not going to sell it until I know for sure whats causing it so I may even end up keeping it lol!

[AnnMar Studios]

well, I have been facing the exact same thing. I have been reading your thread cause its the same!

but no I have not solved the issue. I have done EVERYTHING possible and same as you , there are times when it appears solved and bam...starts up again.

crazy...I am going after it hard this week, as I need to get it out.

thanks!@ for all your help!@@!

[Chuckl]

Don't worry. Some day you will visit a cybercafe or office so equipped.
Thanks for trying.

Ouch!