Vox AD120VT Problem

[J M Fahey]

WHO repairs Electronic stuff any more?
Excluding a few Dodos still running around until their irreplaceable batteries fully discharge, that is

[imf]

WHO repairs Electronic stuff any more?
Excluding a few Dodos still running around until their irreplaceable batteries fully discharge, that is

lol Indeed... not many do. If an electronic product goes bad and it's out of warranty, it's contributed to the e-waste dumps in China without hesitation. Radioshack was like a cell phone store these days basically, at least that's probably where most their revenue came from and maybe some other small electronics stuff like component cables, audio/video stuff, batteries, etc. They had way too many storefronts open, that was the problem. Add in Amazon and online retail in general... and that place is history.

[Enzo]

People throw out mass market commodity stuff, like $89 amplifiers and computer monitors. No one throws away $2000 Marshalls or $4000 synths or multi-thousand dollar mix boards, etc. You don't take your $200 beater car to the shop for a new $400 clutch job or transmission rebuild. You DO take your $50,000 Benz in for...whatever it wants.

So one should not open a shop repairing $200 cars or $89 amps and expect to make any money.

[Enzo]

People throw out mass market commodity stuff, like $89 amplifiers and computer monitors. No one throws away $2000 Marshalls or $4000 synths or multi-thousand dollar mix boards, etc. You don't take your $200 beater car to the shop for a new $400 clutch job or transmission rebuild. You DO take your $50,000 Benz in for...whatever it wants.

So one should not open a shop repairing $200 cars or $89 amps and expect to make any money.

[imf]

People throw out mass market commodity stuff, like $89 amplifiers and computer monitors. No one throws away $2000 Marshalls or $4000 synths or multi-thousand dollar mix boards, etc. You don't take your $200 beater car to the shop for a new $400 clutch job or transmission rebuild. You DO take your $50,000 Benz in for...whatever it wants.

So one should not open a shop repairing $200 cars or $89 amps and expect to make any money.

For sure I agree there. In my previous post I actually started to say something similar like the best market for electronics repair is music instruments, expensive audio/video gear and maybe some appliances that are worth the trouble to pay for a repair over buying new. I don't even want to get rid of this ad120vt as it was fairly expensive, but the tech was basically telling me to.

I have an interest in learning and this gives me a good goal to try for, but someone who didn't have an interest in electronics would probably try and sell it as is, or give it away. That's the same thing I would do with an over-engineered German car like a Benz or even worse bmw that was out of warranty. Pick up a nicely built Japanese car next time that will last forever and much cheaper to fix and work on. That's what I plan to do with my next amp as well. Nicely built and simple. btw, nothing against all German cars, I like Porsche.

[Enzo]

I have an AD120VT, like new, with unrepairable digital board. Sturdy, nice speakers, I figured better for use to build a project in than to buy new boards for.

[imf]

I have an AD120VT, like new, with unrepairable digital board. Sturdy, nice speakers, I figured better for use to build a project in than to buy new boards for.

I was thinking that too as a possibility if I can't get this to work. It's a very sturdy build for sure, the reason I kept it around was actually for the speakers until I turned it on last week and got sound out of the effects send, then said to myself... well the preamp section is working fine.

Update on the shipment from mouser... the extra $2 is totally worth it. They shipped it out today and will be here on Monday so that's not bad at all.

[J M Fahey]

Good.
If the preamp works, the power section is repairable.

*Absolute* worst case, if the somewhat complex hybrid power section is bad and out of reach, (they embedded a 12AX7 into it with a complex NFB network so the whole power amp "behaves like a full Tube one") you add your own power module fed from current power supply and drive existing speakers with it.
Sound will still be very good.

I repaired a friend´s one who plugged a 120V amp into 220V mains, blowing the STK404-130 power module and some associated parts, but preamp and tube section survived.
His was the 100W , +/-51V rails version, yours should be quite close to it.

[imf]

Good.
If the preamp works, the power section is repairable.

*Absolute* worst case, if the somewhat complex hybrid power section is bad and out of reach, (they embedded a 12AX7 into it with a complex NFB network so the whole power amp "behaves like a full Tube one") you add your own power module fed from current power supply and drive existing speakers with it.
Sound will still be very good.

I repaired a friend´s one who plugged a 120V amp into 220V mains, blowing the STK404-130 power module and some associated parts, but preamp and tube section survived.
His was the 100W , +/-51V rails version, yours should be quite close to it.

Nice, thanks M Fahey, that sounds like the first thing to shoot for with this if things don't work out as I hope they will. I'll report back to the thread as soon as I get that resistor in and see where I'm at.

[imf]

Update - I got the part from mouser today and soldered it in.

The amp works like a charm! Unbelievable!! A stupid 1k resistor... I'm so pissed I didn't try this sooner. So much for that amp tech I took it to... WOW, I don't know what to say about that without coming off like an enraged lunatic with a foul mouth.

nickb, The Dude, eschertron... you guys are great, seriously thanks a lot for helping me out. Really appreciate it.

Now I just have to put this mess back together...

[imf]

In my opinion this thing sounds killer. Compared to what I was using for practice anyway. One thing is, it's a little noisy but not too bad to me. I'm thinking it's the grounding in the unit, maybe I could better that. I love the fender models, the UK '70S and especially the UK '80S model is awesome.

I don't have a real deal tube amp to compare it with but I'd like to pickup some kind of 50w Marshall 2204 variant or possibly build a 2204 clone as a future project and experiment with speakers as I think that's where a lot can change, but these speakers seem well matched for this.

[J M Fahey]

Oh, it does sound real good!!
In part, because the "mystery" so called "Wharfedale" speakers they fit there sound quite good.
Might even be OEM made by Celestion or at least are good close copies of.
Glad you solved it

[Enzo]

I think mine says Celestion on the magnet.

[eschertron]

My AD60VTX came with Neo speakers 'labeled Neo-Dog', IIRC they are Celestions.
And yes, it sounds great for the application. When I need to evoke country on one song, and Dr. May on the next, the VTX amp works a treat!

edit: 'speaker' singular for the 60, you have 2x12 in the 120, correct?

[imf]

Yeah, made by Celestion, the logo is on mine as well.

Yes, I have the 2x12 120 - this thing is loud as hell though, I would have been fine with the 60... I usually keep it on 15x2 power setting, 30x2 when I wanna piss the neighbors off, but it's really too loud. 60x2 might take my walls down fully cranked. Good times... great to have this thing kickin' again.