Marshall Amplification Marshall AS50D Acoustic Guitar Amplifier (50 Watts, 2x8 in.) - Answered Questions & Fixed issues

https://www.dropbox.com/s/6spu98r39t2wvcr/Marshall%20G30RCD%20Schematic.pdf

https://www.manualslib.com/manual/99237/Marshall-Amplification-Mg15msii.html

Most likely cause for this is an intermittent potentiometer. Check to see if any of them are mechanically loose as this is a sign that they have been damaged and could have cracked the wiper surface inside the pot causing this problem. Alternatively, any switch that controls any gain setting could also be intermittent or dirty. Gain of the amplifier should be stable, but is controlled by the feedback and signal injection at the pots so that is where to look first. Good luck, as intermittent problems are tricky, but sometimes better than no function at all which can be more costly.

Hi. Doesn't look like it as the speaker is a 4 ohm one and the head needs at least 8 ohm as far as I can see.

What type of Marshall, please? First of all, control the fuse and let me know.

clean switch connections

Does anything happen while you turn the knobs on the amp? I had a similar problem with a yamaha amp. It turned out a couple of knobs went bad. Soldered new pots and it works fine for me now.

No, the ATV50 head is rated for 4 ohms total. Using both 4 ohm cabinets at once will fry your amp. Your only option would be to rewire your cabs internally to 16 ohms each by connecting the speakers in parallel, but that would cut your amp's power in half.

No, the ATV50 head is rated for 4 ohms total. Using both 4 ohm cabinets at once will fry your amp.

http://www.manualslib.com/brand/marshall-amplification/amplifier.html Scroll down alphabetically.

Make sure speaker cable works and is connected then check fuses. If it has a master volume, make sure it's turned up.

Some Marshall serial numbers might tell you the year your 3005 was made, Marshall stamped the different years of the micro's in different spots, your number could either be on the back metal plate stamped right above the AC power cable port, or barely visible on the front gold plate above the power switch just under the Tolex, at least that's where my 1988 3005's serial number is stamped. But it should have one on it somewhere, could even be inside the head too, my sis plays and has an old 1977 50watt tube head with an interior serial number. I've been a huge fan of the Micro stacks since they came out in the mid-80's. I believe the 3005's were only produced from 1985 or so till around 1988 or 89 in Black, White, Red, Orange, Blue, Purple, and Grey, a Camo Tolex was a custom option as far as I remember. 1987 was Marshall's Silver 25th Anniversary, so a Silver Tolex Jubilee edition was made that year only. Than the newer MG15-II's were made from around 2004 till 2010 along with the Zakk Wylde signature series micro stack,. And now they make the newer MGD's since 2010, I just tried one last week at my local guitar shop, I liked it a lot, it's very different sounding than my old 1988 or my 2009 micro's and has a few built in effects which weren't great, but not that bad at all, I have a 1988 3005 stack that came with Celestion G-10's in the cabs and an MG15-II series micro stacks, that one came with some no name 10's, but believe it or not they sound better than the G-10's! Mine are all in black, I have been after an original micro stack in white for many years.Did your old 1x10 cabs come with Celestions too?

Open the cabinet (remove back panel). Either a wire came loose or one of those 2 speakers is blown.

First check the preamp valve in that curcuit

It may be dirty, spray it with contact cleaner, and also make sure the retaining nut is tight and solder connections are sound.If the jack is actually damaged, you can get suitable replacements from http://www.tubesandmore.com Digikey and mouser have them too, but the price is about the same with less searching. Also check to make sure any connectors into the preamp are snug and secure as well.

If you are competent with electronics, open it up and check the fuse(s). Especially if no lights come on. If you get voltage, then check the jacks you plugged into- they may have dirty interrupt contacts. When you plug the jack in- it opens those contacts that otherwise are closed making the circuit to the cabinet's built in speaker. Contact cleaner should clean them up if that is the issue.While it is possible there is a power supply issue, you can see that quick with a voltmeter, it is not likely you did much more than blow a fuse.- very possible if you unplugged speakers with the amp operating..If you think you killed it- you usually still get distorted noise.

It is unlikely that your actions with the plug strip caused any permanent damage to your unit.

If you unit has a digital effects unit, probably the setting for that got disturbed and you need to reset it to your desired setting.

Check for ground loops. Make sure the pedal power and amp are plugged into the same receptacle. Keep cables short, and if necessaary go to balanced lines to the amp. DO NOT have any lamp dimmers in the area of the audio cable to the amp. Use high quality instrument amp cables that have good shielding... DO NOT use speaker cables.

'pianoforte'