Problem with Marshall AVT150

[Ali___]

Hi folks, I think I know the answer to this one but I'm currently getting a lot of crackling through my AVT at the moment. It mainly happens on the overdrive channels but is also present on the acoustic sim as well. The clean channel doesn't seem affected at all.

It literally sounds like static crackling rather than any hum and seems independant of the guitar. Do I need a new valve? If so, can anyone recommend any valves that they've found to improve the AVT?

[tech_dude]

It doesn't sound like it's the tube but for 10 bucks, I would change it if the amp is older than a year for an ocassional player and 6 months if you gig hard all the time. These AVT amps have the input jack soldered to the board. Everytime you wiggle your cord a bit....it pulls on the solder joints of the jack. I see this time and time again. Most of the time I just touch the joints with the iron and they will reattach quite easy. If you are doing this yourself............becareful...........you don't need much heat to melt the solder............those big guns can get hot fast and lift the path off the board! Then you will have problems. There is a big green wire that grounds the board to the chasis.........these are often loose. There is a blade connector on the end that attaches to the chasis............remove it and clean the chasis part with sandpaper or a dremel tool............then slightly crimp the blade connector with needle nose pliers and reattach it to the ground. Even if this doesn't solve the original problem........it will sure help secure things from future problems. Try another speaker to make sure it's not something there. Good luck.

[Ali___]

Thanks for that tech-dude. Fairly sure it's not the speaker as I get the same problem from the headphones. It, rather oddly, has calmed down a lot over the last couple of days. I think part of the problem is the lack of use the amp gets. With a noise sensitive wife and a young kid I rarely get a chance to play it, using the GT6 mainly through headphones instead, so I was wondering if that could have any effect?

One thing I'm glad of, it's not my Universe Was worried it might be faulty and I love it to much to lose it for weeks on end to our local (very slow) guitar store.

Still, the AVT is merely a stop-gap until I've bought my Jem VWH and then can decide on a better quality amp. Having said that, I still really like the AVT's sound. It just doesn't get on well with my GT6- very hard to get a decent replication of the GT6's headphone output.

I'll have a look internally and see what I can see, once the capacitors have discharged that is

[mike777]

If the unit is still under warranty - let an authorized service center (as per the manufacturer or distributor) do it - even if you think the problem may not be covered. Most manufacturer's warranties become void when someone other than an manufacturer-authorized service center/technician goes into the unit. This could save you a lot of grief if something more significant happens in the future while under warranty. Here in the US, Marshall's warranty is much greater than one year but I don't know about the other countries.

Mike 777 Haug

[Algiman]

Originally Posted by mike777

Here in the US, Marshall's warranty is much greater than one year but I don't know about the other countries.

Mike 777 Haug

I'm pretty sure it is 3 years here in the UK. If you can get it sent to the factory itself all the better. One of my mates took his TSL there after an accident with a gin and tonic (very rock and roll!) and got superb customer service. As the amp was less than 3 years old they also gave it a full service and revalve free.