Jvm 410h squeals with feedback in most distorted modes at about half volume even when guitar volume is off

If this happens only when the guitar is plugged in, most likely there are two possibilities. The first, you have some issues with the electronics in the guitar OR are using an acoustic guitar witch has an extremely sensitive pickup that provides nothing but feedback. If this is happening with the guitar unplugged, there is a mountain of possibilities.

yes, if you know what is the amp module check.

I'm not sure which amp you're playing thru. but generally the settings you want for a clean sound. check your drive (or Gain ) knob. You want it about half way.and your Channel volume, half way. those are good starts. then let your master volume do the rest. Also, make sure, if you have active pick-ups on your guitar. check the batteries. if they're low, it can cause distortion. if this doesn't resolve, then its internal. could be anything at that point.

I have had this problem at least two times and the fault was a bad hi voltage filter capacitor. With the back of the amplifier removed, it's the grey cap near the top right side. Warning: very dangerous voltage there!!

You need to check the actual signal levels to make sure they are within the specs for the unit. The mic input is low impedance. Your mic should be like a Shure SM58 or equivalent. The output is fairly high... up to +14DB which will require you to turn down the trims on a mixer this runs into or set a -20Db pad at the input. I suspect your distortion is from the device output to the mixer input. It is VERY important that the mic does NOT "hear" the speakers as the feedback loop resulting will be mass distortion. The guitar should also not "hear" the mains.

Dampen the strings of your guitar. If feedback disappears, then you need to move the amp so it can't resonate the strings of the guitar. OD1 and OD2 WORSEN the chances of the feedback into the strings. When this occurs you can often see the strings vibrating without the player picking them.

You should check if the thing does it with a guitar plugged in.

The shorting switch for input connectors that keeps the input grounded are prone to failure.

You can reach the limiting IRRESPECTIVE of where the volume control is set when you have a guitar or other source that has HIGH output.

Guitars that have battery in them with internal amplifiers are an example of a high output guitar. Plain inductive pickups may require the volume control to be set at say 70% to reach limiting.

Please NOTE that the volume control is NOT linear, but is an "audio taper".

Limiting means you are probably driving it too hard. Many learn the hard way when speakers and thee power amp fail.

When the cone is driven too far beyond the pole pieces of the magnet, then the IMPEDANCE of the speaker becomes relatively low and can damage the power amp. The limiter tries to prevent this by sensing the current and or voltage and will back off the gain internally. This causes distortion when it happens.

Sounds like your master volume is turned up too much. The channel volume will make the squealing go away(caused by high gain and humbuckers). The best thing to do is dial in your favorite presets and change the channel volume to the correct level with the master volume where you usually keep it. I use my Spider Valve at master volume at about noon and the channel volume between nine o'clock and noon. Let me know if this does not solve the problem......

Hi,

It's not your pickups. It would be nearly impossible to loosen a wire inside of your guitar by having even heavier than your amp head drop on it. It is most likely your volume pot. The post, if hit hard enough, can virtually distroy your pots. Another possibility could be your jack, al though considering where it's located on your guitar, it would be very hard to damage it by having something drop onto it.

There is little else that could be the problem. Hopefully you didn't damage your guitar too badly. If the guitar was in front of me, it would be a relatively easy diagnosis.

Fortunately, volume and tone pots are inexpensive, and if you're handy with a soldering iron (or you have a friend that is) it is an easy install with four to six solder points, depending on your configuration. I don't want to assume it's a stock setup, but when you take off the rear electronics cover, you will immediately see what configuration you have.

If you have possibly damaged the pickup bobbins (assuming you have the stock humbuckers in your guitar), you would be able to see the damage, It would either look damaged,or work correctly. As you know bobbuns are simply wound wire, and that's not easy to damage. Plus your strings provide a minimal amount of protection, unless your amp head slammed it very hard. Start by replacing the volume pot. Cheapest parts first. There is no way to test the pot with anything like a potentiometer, because there is virtually no voltage that passes through the pot. Additionally, unless you have active pickups, your pickups cannot be either. If you do have to replace your electronics, you can find a large variety and even upgrade your parts by searching eBay. The good thing is that you havce a guitar, and guitar parts are abundant, relatively cheap, and most people change out electronics just to achieve a different sound.

If you are so inclined, most good guitar shops will diagnose your problem for cheap and apply the cost of the diagnosis to the cost of the repair. Good luck, and I hope I have given you some information to work with.

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