Question about Marshall Amplification Marshall Amp Cover for AVT50H
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Posted on Jan 02, 2017
Try carefully cleaning your cooling fan with qtips for the blades and a vacuumn. See if that helps the fan. If not it will need to be replaced. If you are experienced with amp repairs have a look for loose parts on the circuit board. If you can safely disassemble it, look at the soldered side for bad solder joints. From another poster on here with the same problem I have learned that resoldering R107 and R96 helped. Make sure they aren't burned out or have changed in value.They are in the FDD circuit. Have a look at your owners manual and it will make sense. The schematic is available here:http://www.ampix.org/displayimage.php?album=search&cat=0&pos=0 If it doesn't come up use the search function on that site. Do not attempt to service this yourself unless you are absolutely sure you won't hurt yourself or the amp.
Posted on Mar 05, 2010
Likely destroyed the rectifiers AND the filter capacitors. Replace the capacitors and the rectifiers. There are a lot of them. There are fuses so some of those may have saved some parts.
D10 through D14 and D16,D17 and D20,D21 Some of these may have survived so test each.
C51 and C52, C26,C34 probably gone. Check the Bias supply is working at expected bias voltage.
Your schematic: http://elektrotanya.com/marshall_jvm410.pdf/download.html
Posted on Feb 05, 2011
may be one of the electrolytic capacitors in the power supply has become leaky...this is a common problem among amplifiers...so you let it cool down..then after a period of time the capacitor heats up and then causes the hum...the power supply caps filter out the 60 hertz ac line noise...which is probably the frequency of the sound it is making...this is a good indication of these caps going bad....another thing you can check is to see if the amp is properly grounded(eg: the ground pin on the plug is present) and that you dont have an open cord or input
Posted on Jul 10, 2011
SOURCE: External Speaker hookup problem. I hooked up 2 external speakers (8 ohm, 160 watt) into my Marshall AVT 50 amp (tag on back says 4 ohm minimum). Everything worked fine, then I shut it down and now (ne
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.
Posted on Mar 30, 2012
Testimonial: "Thanks - I'll pass this on to the guy looking at it. I'd like to believe it's just a fuse, but I'm preparing for a blown output transformer. I'm still not sure why it blew - two 8 ohm speakers in parallel should be 4 ohms, and that's what the amp was rated for. Even when (for a short time) I had only 1 speaker hooked up, those 8 ohms would just decrease the efficiency, right, not cause the transformer to blow? Obviously, I'm trying to understand this so that it doesn't happen again! Thanks for your help!"
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